Table of Contents
What is Tap drill Size?
“Tap Dill Size” is the drill diameter we should use before a tapping operation. By default, the size you will find on most charts is the diameter for 75% thread depth on a Cutting Tap. Here you will learn how to get the right drill diameter depending on the tap type and required thread height.
Tap Drill Size Calculator
Tap Drill Size Formulas
Parameters:
- TD – Tap Drill Diameter (mm / Inch)
- D – Nominal Thread Diameter (mm / Inch)
- H – Thread Depth (mm / Inch)
- Hmax – Maximum thread depth according to thread standards.
- Hp – Thread Depth (In percentage)
- Hp = 100*(Hmax-H)/Hmax
- P – Pitch (distance in mm)
- TPI – Pitch (Pitch expressed as tooth per Inch)
Formulas:
| Tapping Technology | Inch Threads | Metric Threads |
|---|---|---|
TTap Cutting |
\(\LARGE D - \frac{H_p}{76.98\,\times\,TPI}\) |
\(\LARGE D - \frac{H_p\,\times\,P}{76.98}\) |
Tap Forming |
\(\LARGE D - \frac{H_p\,\times\,P}{294.12}\) |
\(\LARGE D - \frac{H_p}{294.12\,\times\,TPI}\) |
Thread Depth (Height) in tapping Explained
The distance between the crest and root is called the thread height. The thread standards define the maximum thread height and are the same for metric and inch threads.
\(H_{max}=\Large \frac{5}{8}\times\frac{\sqrt{3}}{2}\normalsize\times{P}\,=\,0.5413\times{P} \)
\( H_{max}=\Large \frac{5}{8}\times\frac{\sqrt{3}}{2}\normalsize\times{P} \)
\(\,=\,0.5413\times{P} \)
In tapping, it is customary to express the thread height (Sometimes called thread depth) as the relation in percentage between the actual depth and the maximum depth.
\( H_{p}=\Large \frac{H_{max}\,-\,H}{H_{max}}\normalsize\times{100} \)
- A larger Thread height means a smaller tap drill size.
- A smaller Thread height means a larger tap drill size.
Why Is it important?
- Since the feed always equals the thread pitch and the entire thread depth is machined in one pass by definition, these factors are not in our control. The thread depth is a primary factor (Next to the cutting speed) influencing a tapping tool’s torque and tool life.
- Increasing the drill size makes tapping easier and extends the tool-life of the tap. However, the strength of the thread is reduced, and the minor diameter can get out of tolerance.
- It is an informal rule that the default thread depth is 75%. Therefore, in most charts you will find in various catalogs or on the web, the value given for the tap drill size is 75% thread height. The actual working range in most cases is 65%-85%.
With our Calculator and Chart , you can get the precise tap drill size as a function of the thread height.
Calculation Examples
Calculating Tap Drill Size for M8 X 1.25 (Metric Thread)
\( \begin{array}{l}
D=8\text{ mm} \\
P=1.25\text{ mm} \\
H_p=65\text{%} \\
TD = 8\,-\,\Large \frac{65\,\times\,1.25}{76.98}\normalsize=\,6.94\text{ mm}
\end{array} \)
Calculating Tap Drill Size for UNC 1/4-20 (InchThread)
\( \begin{array}{l}
D=0.25\text{“} \\
TPI=20\text{ Tooth per Inch} \\
H_p=80\text{%} \\
TD = 0.25\,-\,\Large \frac{80}{76.98\,\times\,20}\normalsize=\,0.198\text{“}
\end{array} \)
- The above examples are for cutting taps.
Tapping technologies
Cutting Taps
- The cutting taps are far more popular and can be used on all materials.
- As its name suggests, it cuts the material in the same way as a milling or turning tool by removing material and generating chips.
- They have flutes (Usually straight).
- The bore diameter created by the tap drill does not change and is the minor diameter of the thread.
Forming Taps
- The forming taps are an alternative solution for cutting taps when machining a thread in soft materials such as aluminum, brass, copper, 300 stainless steel, and low carbon steel.
- As its name suggests, it forms the thread by pressing the material.
- They Don’t have flutes (Sometimes they have narrow lubrication grooves).
- The bore diameter created by the tap drill gets smaller due to the material that is pushed to create a thread. This “material growth” should be taken into account.
Advantages of Forming Taps (Compared with cutting taps):
- The cycle time is shorter due to higher cutting speeds.
- Better uniformity and accuracy of the thread.
- A higher strength of the thread (Due to internal stress created by the forming process).
- No chips are formed, therefore there is never a chip evacuation issue.
Disadvantages of Forming Taps (Compared with cutting taps):
- They can be used only on ductile materials such as aluminum, brass, copper, 300 series stainless steel, and low carbon steel.
- Forming taps generate higher torque. This becomes more problematic in larger diameters.
- They are more sensitive to fractures, especially if not applied correctly.
Tap Dill Size Chart
Unified Inch Threads (UNC/UNF/UNEF) Tap Drill Size Chart
Tap Drill size per thread height (In percentage)
- Press ⊕ to view all Width (55%-85%).
| Thread | 55% (Width) | 60% | 65% | 70% | 75% | 80% | 85% |
|---|---|---|---|---|---|---|---|
| #0 - 80 UNF | 0.051" (1.3 mm) | 0.05" (1.28 mm) | 0.049" (1.26 mm) | 0.049" (1.24 mm) | 0.048" (1.21 mm) | 0.047" (1.19 mm) | 0.046" (1.17 mm) |
| #1 - 64 UNC | 0.062" (1.57 mm) | 0.061" (1.54 mm) | 0.06" (1.52 mm) | 0.059" (1.49 mm) | 0.058" (1.47 mm) | 0.057" (1.44 mm) | 0.056" (1.42 mm) |
| #1 - 72 UNF | 0.063" (1.6 mm) | 0.062" (1.58 mm) | 0.061" (1.56 mm) | 0.06" (1.53 mm) | 0.059" (1.51 mm) | 0.059" (1.49 mm) | 0.058" (1.46 mm) |
| #2 - 56 UNC | 0.073" (1.86 mm) | 0.072" (1.83 mm) | 0.071" (1.8 mm) | 0.07" (1.77 mm) | 0.069" (1.74 mm) | 0.067" (1.71 mm) | 0.066" (1.68 mm) |
| #2 - 64 UNF | 0.075" (1.9 mm) | 0.074" (1.88 mm) | 0.073" (1.85 mm) | 0.072" (1.82 mm) | 0.071" (1.8 mm) | 0.07" (1.77 mm) | 0.069" (1.75 mm) |
| #3 - 48 UNC | 0.084" (2.14 mm) | 0.083" (2.1 mm) | 0.081" (2.07 mm) | 0.08" (2.03 mm) | 0.079" (2. mm) | 0.077" (1.96 mm) | 0.076" (1.93 mm) |
| #3 - 56 UNF | 0.086" (2.19 mm) | 0.085" (2.16 mm) | 0.084" (2.13 mm) | 0.083" (2.1 mm) | 0.082" (2.07 mm) | 0.08" (2.04 mm) | 0.079" (2.01 mm) |
| #4 - 40 UNC | 0.094" (2.39 mm) | 0.093" (2.35 mm) | 0.091" (2.31 mm) | 0.089" (2.27 mm) | 0.088" (2.23 mm) | 0.086" (2.18 mm) | 0.084" (2.14 mm) |
| #4 - 48 UNF | 0.097" (2.47 mm) | 0.096" (2.43 mm) | 0.094" (2.4 mm) | 0.093" (2.36 mm) | 0.092" (2.33 mm) | 0.09" (2.29 mm) | 0.089" (2.26 mm) |
| #5 - 40 UNC | 0.107" (2.72 mm) | 0.106" (2.68 mm) | 0.104" (2.64 mm) | 0.102" (2.6 mm) | 0.101" (2.56 mm) | 0.099" (2.52 mm) | 0.097" (2.47 mm) |
| #5 - 44 UNF | 0.109" (2.76 mm) | 0.107" (2.73 mm) | 0.106" (2.69 mm) | 0.104" (2.65 mm) | 0.103" (2.61 mm) | 0.101" (2.58 mm) | 0.1" (2.54 mm) |
| #6 - 32 UNC | 0.116" (2.94 mm) | 0.114" (2.89 mm) | 0.112" (2.83 mm) | 0.11" (2.78 mm) | 0.108" (2.73 mm) | 0.106" (2.68 mm) | 0.103" (2.63 mm) |
| #6 - 40 UNF | 0.12" (3.05 mm) | 0.119" (3.01 mm) | 0.117" (2.97 mm) | 0.115" (2.93 mm) | 0.114" (2.89 mm) | 0.112" (2.85 mm) | 0.11" (2.8 mm) |
| #6 - 32 32-UN | 0.116" (2.94 mm) | 0.114" (2.89 mm) | 0.112" (2.83 mm) | 0.11" (2.78 mm) | 0.108" (2.73 mm) | 0.106" (2.68 mm) | 0.103" (2.63 mm) |
| #8 - 32 UNC | 0.142" (3.6 mm) | 0.14" (3.55 mm) | 0.138" (3.5 mm) | 0.136" (3.44 mm) | 0.134" (3.39 mm) | 0.132" (3.34 mm) | 0.129" (3.29 mm) |
| #8 - 36 UNF | 0.144" (3.66 mm) | 0.142" (3.62 mm) | 0.141" (3.57 mm) | 0.139" (3.52 mm) | 0.137" (3.48 mm) | 0.135" (3.43 mm) | 0.133" (3.39 mm) |
| #8 - 32 32-UN | 0.142" (3.6 mm) | 0.14" (3.55 mm) | 0.138" (3.5 mm) | 0.136" (3.44 mm) | 0.134" (3.39 mm) | 0.132" (3.34 mm) | 0.129" (3.29 mm) |
| #10 - 24 UNC | 0.16" (4.07 mm) | 0.158" (4. mm) | 0.155" (3.93 mm) | 0.152" (3.86 mm) | 0.149" (3.79 mm) | 0.147" (3.73 mm) | 0.144" (3.66 mm) |
| #10 - 32 UNF | 0.168" (4.26 mm) | 0.166" (4.21 mm) | 0.164" (4.16 mm) | 0.162" (4.1 mm) | 0.16" (4.05 mm) | 0.158" (4. mm) | 0.155" (3.95 mm) |
| #10 - 32 32-UN | 0.168" (4.26 mm) | 0.166" (4.21 mm) | 0.164" (4.16 mm) | 0.162" (4.1 mm) | 0.16" (4.05 mm) | 0.158" (4. mm) | 0.155" (3.95 mm) |
| #12 - 24 UNC | 0.186" (4.73 mm) | 0.184" (4.66 mm) | 0.181" (4.59 mm) | 0.178" (4.52 mm) | 0.175" (4.46 mm) | 0.173" (4.39 mm) | 0.17" (4.32 mm) |
| #12 - 28 UNF | 0.19" (4.84 mm) | 0.188" (4.78 mm) | 0.186" (4.72 mm) | 0.184" (4.66 mm) | 0.181" (4.6 mm) | 0.179" (4.54 mm) | 0.177" (4.48 mm) |
| #12 - 32 UNEF | 0.194" (4.92 mm) | 0.192" (4.87 mm) | 0.19" (4.82 mm) | 0.188" (4.76 mm) | 0.186" (4.71 mm) | 0.184" (4.66 mm) | 0.181" (4.61 mm) |
| #12 - 28 28-UN | 0.19" (4.84 mm) | 0.188" (4.78 mm) | 0.186" (4.72 mm) | 0.184" (4.66 mm) | 0.181" (4.6 mm) | 0.179" (4.54 mm) | 0.177" (4.48 mm) |
| #12 - 32 32-UN | 0.194" (4.92 mm) | 0.192" (4.87 mm) | 0.19" (4.82 mm) | 0.188" (4.76 mm) | 0.186" (4.71 mm) | 0.184" (4.66 mm) | 0.181" (4.61 mm) |
| 1 ⁄4 - 20 UNC | 0.214" (5.44 mm) | 0.211" (5.36 mm) | 0.208" (5.28 mm) | 0.205" (5.2 mm) | 0.201" (5.11 mm) | 0.198" (5.03 mm) | 0.195" (4.95 mm) |
| 1 ⁄4 - 28 UNF | 0.224" (5.7 mm) | 0.222" (5.64 mm) | 0.22" (5.58 mm) | 0.218" (5.53 mm) | 0.215" (5.47 mm) | 0.213" (5.41 mm) | 0.211" (5.35 mm) |
| 1 ⁄4 - 32 UNEF | 0.228" (5.78 mm) | 0.226" (5.73 mm) | 0.224" (5.68 mm) | 0.222" (5.63 mm) | 0.22" (5.58 mm) | 0.218" (5.53 mm) | 0.215" (5.47 mm) |
| 1 ⁄4 - 20 20-UN | 0.214" (5.44 mm) | 0.211" (5.36 mm) | 0.208" (5.28 mm) | 0.205" (5.2 mm) | 0.201" (5.11 mm) | 0.198" (5.03 mm) | 0.195" (4.95 mm) |
| 1 ⁄4 - 28 28-UN | 0.224" (5.7 mm) | 0.222" (5.64 mm) | 0.22" (5.58 mm) | 0.218" (5.53 mm) | 0.215" (5.47 mm) | 0.213" (5.41 mm) | 0.211" (5.35 mm) |
| 1 ⁄4 - 32 32-UN | 0.228" (5.78 mm) | 0.226" (5.73 mm) | 0.224" (5.68 mm) | 0.222" (5.63 mm) | 0.22" (5.58 mm) | 0.218" (5.53 mm) | 0.215" (5.47 mm) |
| 5 ⁄16 - 18 UNC | 0.273" (6.93 mm) | 0.269" (6.84 mm) | 0.266" (6.75 mm) | 0.262" (6.65 mm) | 0.258" (6.56 mm) | 0.255" (6.47 mm) | 0.251" (6.38 mm) |
| 5 ⁄16 - 24 UNF | 0.283" (7.18 mm) | 0.28" (7.11 mm) | 0.277" (7.04 mm) | 0.275" (6.98 mm) | 0.272" (6.91 mm) | 0.269" (6.84 mm) | 0.266" (6.77 mm) |
| 5 ⁄16 - 32 UNEF | 0.29" (7.37 mm) | 0.288" (7.32 mm) | 0.286" (7.27 mm) | 0.284" (7.22 mm) | 0.282" (7.16 mm) | 0.28" (7.11 mm) | 0.278" (7.06 mm) |
| 5 ⁄16 - 20 20-UN | 0.277" (7.03 mm) | 0.274" (6.95 mm) | 0.27" (6.87 mm) | 0.267" (6.78 mm) | 0.264" (6.7 mm) | 0.261" (6.62 mm) | 0.257" (6.54 mm) |
| 5 ⁄16 - 28 28-UN | 0.287" (7.29 mm) | 0.285" (7.23 mm) | 0.282" (7.17 mm) | 0.28" (7.11 mm) | 0.278" (7.05 mm) | 0.275" (6.99 mm) | 0.273" (6.94 mm) |
| 5 ⁄16 - 32 32-UN | 0.29" (7.37 mm) | 0.288" (7.32 mm) | 0.286" (7.27 mm) | 0.284" (7.22 mm) | 0.282" (7.16 mm) | 0.28" (7.11 mm) | 0.278" (7.06 mm) |
| 3 ⁄8 - 16 UNC | 0.33" (8.39 mm) | 0.326" (8.29 mm) | 0.322" (8.18 mm) | 0.318" (8.08 mm) | 0.314" (7.98 mm) | 0.31" (7.88 mm) | 0.306" (7.77 mm) |
| 3 ⁄8 - 24 UNF | 0.345" (8.77 mm) | 0.343" (8.7 mm) | 0.34" (8.63 mm) | 0.337" (8.56 mm) | 0.334" (8.49 mm) | 0.332" (8.43 mm) | 0.329" (8.36 mm) |
| 3 ⁄8 - 32 UNEF | 0.353" (8.96 mm) | 0.351" (8.91 mm) | 0.349" (8.85 mm) | 0.347" (8.8 mm) | 0.345" (8.75 mm) | 0.343" (8.7 mm) | 0.34" (8.65 mm) |
| 3 ⁄8 - 16 16-UN | 0.33" (8.39 mm) | 0.326" (8.29 mm) | 0.322" (8.18 mm) | 0.318" (8.08 mm) | 0.314" (7.98 mm) | 0.31" (7.88 mm) | 0.306" (7.77 mm) |
| 3 ⁄8 - 20 20-UN | 0.339" (8.62 mm) | 0.336" (8.54 mm) | 0.333" (8.45 mm) | 0.33" (8.37 mm) | 0.326" (8.29 mm) | 0.323" (8.21 mm) | 0.32" (8.12 mm) |
| 3 ⁄8 - 28 28-UN | 0.349" (8.88 mm) | 0.347" (8.82 mm) | 0.345" (8.76 mm) | 0.343" (8.7 mm) | 0.34" (8.64 mm) | 0.338" (8.58 mm) | 0.336" (8.52 mm) |
| 3 ⁄8 - 32 32-UN | 0.353" (8.96 mm) | 0.351" (8.91 mm) | 0.349" (8.85 mm) | 0.347" (8.8 mm) | 0.345" (8.75 mm) | 0.343" (8.7 mm) | 0.34" (8.65 mm) |
| 7 ⁄16 - 14 UNC | 0.386" (9.82 mm) | 0.382" (9.7 mm) | 0.377" (9.58 mm) | 0.373" (9.46 mm) | 0.368" (9.34 mm) | 0.363" (9.23 mm) | 0.359" (9.11 mm) |
| 7 ⁄16 - 20 UNF | 0.402" (10.21 mm) | 0.399" (10.12 mm) | 0.395" (10.04 mm) | 0.392" (9.96 mm) | 0.389" (9.88 mm) | 0.386" (9.79 mm) | 0.382" (9.71 mm) |
| 7 ⁄16 - 28 UNEF | 0.412" (10.46 mm) | 0.41" (10.41 mm) | 0.407" (10.35 mm) | 0.405" (10.29 mm) | 0.403" (10.23 mm) | 0.4" (10.17 mm) | 0.398" (10.11 mm) |
| 7 ⁄16 - 16 16-UN | 0.393" (9.98 mm) | 0.389" (9.88 mm) | 0.385" (9.77 mm) | 0.381" (9.67 mm) | 0.377" (9.57 mm) | 0.373" (9.46 mm) | 0.368" (9.36 mm) |
| 7 ⁄16 - 20 20-UN | 0.402" (10.21 mm) | 0.399" (10.12 mm) | 0.395" (10.04 mm) | 0.392" (9.96 mm) | 0.389" (9.88 mm) | 0.386" (9.79 mm) | 0.382" (9.71 mm) |
| 7 ⁄16 - 28 28-UN | 0.412" (10.46 mm) | 0.41" (10.41 mm) | 0.407" (10.35 mm) | 0.405" (10.29 mm) | 0.403" (10.23 mm) | 0.4" (10.17 mm) | 0.398" (10.11 mm) |
| 7 ⁄16 - 32 32-UN | 0.415" (10.55 mm) | 0.413" (10.49 mm) | 0.411" (10.44 mm) | 0.409" (10.39 mm) | 0.407" (10.34 mm) | 0.405" (10.29 mm) | 0.403" (10.24 mm) |
| 1 ⁄2 - 13 UNC | 0.445" (11.3 mm) | 0.44" (11.18 mm) | 0.435" (11.05 mm) | 0.43" (10.92 mm) | 0.425" (10.8 mm) | 0.42" (10.67 mm) | 0.415" (10.54 mm) |
| 1 ⁄2 - 20 UNF | 0.464" (11.79 mm) | 0.461" (11.71 mm) | 0.458" (11.63 mm) | 0.455" (11.55 mm) | 0.451" (11.46 mm) | 0.448" (11.38 mm) | 0.445" (11.3 mm) |
| 1 ⁄2 - 28 UNEF | 0.474" (12.05 mm) | 0.472" (11.99 mm) | 0.47" (11.93 mm) | 0.468" (11.88 mm) | 0.465" (11.82 mm) | 0.463" (11.76 mm) | 0.461" (11.7 mm) |
| 1 ⁄2 - 16 16-UN | 0.455" (11.57 mm) | 0.451" (11.46 mm) | 0.447" (11.36 mm) | 0.443" (11.26 mm) | 0.439" (11.15 mm) | 0.435" (11.05 mm) | 0.431" (10.95 mm) |
| 1 ⁄2 - 20 20-UN | 0.464" (11.79 mm) | 0.461" (11.71 mm) | 0.458" (11.63 mm) | 0.455" (11.55 mm) | 0.451" (11.46 mm) | 0.448" (11.38 mm) | 0.445" (11.3 mm) |
| 1 ⁄2 - 28 28-UN | 0.474" (12.05 mm) | 0.472" (11.99 mm) | 0.47" (11.93 mm) | 0.468" (11.88 mm) | 0.465" (11.82 mm) | 0.463" (11.76 mm) | 0.461" (11.7 mm) |
| 1 ⁄2 - 32 32-UN | 0.478" (12.13 mm) | 0.476" (12.08 mm) | 0.474" (12.03 mm) | 0.472" (11.98 mm) | 0.47" (11.93 mm) | 0.468" (11.88 mm) | 0.465" (11.82 mm) |
| 9 ⁄16 - 12 UNC | 0.503" (12.78 mm) | 0.498" (12.64 mm) | 0.492" (12.5 mm) | 0.487" (12.36 mm) | 0.481" (12.23 mm) | 0.476" (12.09 mm) | 0.47" (11.95 mm) |
| 9 ⁄16 - 18 UNF | 0.523" (13.28 mm) | 0.519" (13.19 mm) | 0.516" (13.1 mm) | 0.512" (13. mm) | 0.508" (12.91 mm) | 0.505" (12.82 mm) | 0.501" (12.73 mm) |
| 9 ⁄16 - 24 UNEF | 0.533" (13.53 mm) | 0.53" (13.46 mm) | 0.527" (13.39 mm) | 0.525" (13.33 mm) | 0.522" (13.26 mm) | 0.519" (13.19 mm) | 0.516" (13.12 mm) |
| 9 ⁄16 - 12 12-UN | 0.503" (12.78 mm) | 0.498" (12.64 mm) | 0.492" (12.5 mm) | 0.487" (12.36 mm) | 0.481" (12.23 mm) | 0.476" (12.09 mm) | 0.47" (11.95 mm) |
| 9 ⁄16 - 16 16-UN | 0.518" (13.15 mm) | 0.514" (13.05 mm) | 0.51" (12.95 mm) | 0.506" (12.84 mm) | 0.502" (12.74 mm) | 0.498" (12.64 mm) | 0.493" (12.53 mm) |
| 9 ⁄16 - 20 20-UN | 0.527" (13.38 mm) | 0.524" (13.3 mm) | 0.52" (13.22 mm) | 0.517" (13.13 mm) | 0.514" (13.05 mm) | 0.511" (12.97 mm) | 0.507" (12.89 mm) |
| 9 ⁄16 - 28 28-UN | 0.537" (13.64 mm) | 0.535" (13.58 mm) | 0.532" (13.52 mm) | 0.53" (13.46 mm) | 0.528" (13.4 mm) | 0.525" (13.34 mm) | 0.523" (13.29 mm) |
| 9 ⁄16 - 32 32-UN | 0.54" (13.72 mm) | 0.538" (13.67 mm) | 0.536" (13.62 mm) | 0.534" (13.57 mm) | 0.532" (13.51 mm) | 0.53" (13.46 mm) | 0.528" (13.41 mm) |
| 5 ⁄8 - 11 UNC | 0.56" (14.23 mm) | 0.554" (14.08 mm) | 0.548" (13.93 mm) | 0.542" (13.78 mm) | 0.536" (13.63 mm) | 0.531" (13.48 mm) | 0.525" (13.33 mm) |
| 5 ⁄8 - 18 UNF | 0.585" (14.87 mm) | 0.582" (14.78 mm) | 0.578" (14.68 mm) | 0.574" (14.59 mm) | 0.571" (14.5 mm) | 0.567" (14.41 mm) | 0.564" (14.32 mm) |
| 5 ⁄8 - 24 UNEF | 0.595" (15.12 mm) | 0.593" (15.05 mm) | 0.59" (14.98 mm) | 0.587" (14.91 mm) | 0.584" (14.84 mm) | 0.582" (14.78 mm) | 0.579" (14.71 mm) |
| 5 ⁄8 - 12 12-UN | 0.565" (14.36 mm) | 0.56" (14.23 mm) | 0.555" (14.09 mm) | 0.549" (13.95 mm) | 0.544" (13.81 mm) | 0.538" (13.68 mm) | 0.533" (13.54 mm) |
| 5 ⁄8 - 16 16-UN | 0.58" (14.74 mm) | 0.576" (14.64 mm) | 0.572" (14.53 mm) | 0.568" (14.43 mm) | 0.564" (14.33 mm) | 0.56" (14.23 mm) | 0.556" (14.12 mm) |
| 5 ⁄8 - 20 20-UN | 0.589" (14.97 mm) | 0.586" (14.89 mm) | 0.583" (14.8 mm) | 0.58" (14.72 mm) | 0.576" (14.64 mm) | 0.573" (14.56 mm) | 0.57" (14.47 mm) |
| 5 ⁄8 - 28 28-UN | 0.599" (15.23 mm) | 0.597" (15.17 mm) | 0.595" (15.11 mm) | 0.593" (15.05 mm) | 0.59" (14.99 mm) | 0.588" (14.93 mm) | 0.586" (14.87 mm) |
| 5 ⁄8 - 32 32-UN | 0.603" (15.31 mm) | 0.601" (15.26 mm) | 0.599" (15.2 mm) | 0.597" (15.15 mm) | 0.595" (15.1 mm) | 0.593" (15.05 mm) | 0.59" (15. mm) |
| 11 ⁄16 - 24 UNEF | 0.658" (16.71 mm) | 0.655" (16.64 mm) | 0.652" (16.57 mm) | 0.65" (16.5 mm) | 0.647" (16.43 mm) | 0.644" (16.36 mm) | 0.641" (16.29 mm) |
| 11 ⁄16 - 12 12-UN | 0.628" (15.95 mm) | 0.623" (15.81 mm) | 0.617" (15.68 mm) | 0.612" (15.54 mm) | 0.606" (15.4 mm) | 0.601" (15.26 mm) | 0.595" (15.13 mm) |
| 11 ⁄16 - 16 16-UN | 0.643" (16.33 mm) | 0.639" (16.23 mm) | 0.635" (16.12 mm) | 0.631" (16.02 mm) | 0.627" (15.92 mm) | 0.623" (15.81 mm) | 0.618" (15.71 mm) |
| 11 ⁄16 - 20 20-UN | 0.652" (16.56 mm) | 0.649" (16.47 mm) | 0.645" (16.39 mm) | 0.642" (16.31 mm) | 0.639" (16.23 mm) | 0.636" (16.14 mm) | 0.632" (16.06 mm) |
| 11 ⁄16 - 28 28-UN | 0.662" (16.81 mm) | 0.66" (16.76 mm) | 0.657" (16.7 mm) | 0.655" (16.64 mm) | 0.653" (16.58 mm) | 0.65" (16.52 mm) | 0.648" (16.46 mm) |
| 11 ⁄16 - 32 32-UN | 0.665" (16.9 mm) | 0.663" (16.84 mm) | 0.661" (16.79 mm) | 0.659" (16.74 mm) | 0.657" (16.69 mm) | 0.655" (16.64 mm) | 0.653" (16.59 mm) |
| 3 ⁄4 - 10 UNC | 0.679" (17.24 mm) | 0.672" (17.07 mm) | 0.666" (16.91 mm) | 0.659" (16.74 mm) | 0.653" (16.58 mm) | 0.646" (16.41 mm) | 0.64" (16.25 mm) |
| 3 ⁄4 - 16 UNF | 0.705" (17.92 mm) | 0.701" (17.81 mm) | 0.697" (17.71 mm) | 0.693" (17.61 mm) | 0.689" (17.5 mm) | 0.685" (17.4 mm) | 0.681" (17.3 mm) |
| 3 ⁄4 - 20 UNEF | 0.714" (18.14 mm) | 0.711" (18.06 mm) | 0.708" (17.98 mm) | 0.705" (17.9 mm) | 0.701" (17.81 mm) | 0.698" (17.73 mm) | 0.695" (17.65 mm) |
| 3 ⁄4 - 12 12-UN | 0.69" (17.54 mm) | 0.685" (17.4 mm) | 0.68" (17.26 mm) | 0.674" (17.13 mm) | 0.669" (16.99 mm) | 0.663" (16.85 mm) | 0.658" (16.71 mm) |
| 3 ⁄4 - 16 16-UN | 0.705" (17.92 mm) | 0.701" (17.81 mm) | 0.697" (17.71 mm) | 0.693" (17.61 mm) | 0.689" (17.5 mm) | 0.685" (17.4 mm) | 0.681" (17.3 mm) |
| 3 ⁄4 - 20 20-UN | 0.714" (18.14 mm) | 0.711" (18.06 mm) | 0.708" (17.98 mm) | 0.705" (17.9 mm) | 0.701" (17.81 mm) | 0.698" (17.73 mm) | 0.695" (17.65 mm) |
| 3 ⁄4 - 28 28-UN | 0.724" (18.4 mm) | 0.722" (18.34 mm) | 0.72" (18.28 mm) | 0.718" (18.23 mm) | 0.715" (18.17 mm) | 0.713" (18.11 mm) | 0.711" (18.05 mm) |
| 3 ⁄4 - 32 32-UN | 0.728" (18.48 mm) | 0.726" (18.43 mm) | 0.724" (18.38 mm) | 0.722" (18.33 mm) | 0.72" (18.28 mm) | 0.718" (18.23 mm) | 0.715" (18.17 mm) |
| 13 ⁄16 - 20 UNEF | 0.777" (19.73 mm) | 0.774" (19.65 mm) | 0.77" (19.57 mm) | 0.767" (19.48 mm) | 0.764" (19.4 mm) | 0.761" (19.32 mm) | 0.757" (19.24 mm) |
| 13 ⁄16 - 12 12-UN | 0.753" (19.13 mm) | 0.748" (18.99 mm) | 0.742" (18.85 mm) | 0.737" (18.71 mm) | 0.731" (18.58 mm) | 0.726" (18.44 mm) | 0.72" (18.3 mm) |
| 13 ⁄16 - 16 16-UN | 0.768" (19.5 mm) | 0.764" (19.4 mm) | 0.76" (19.3 mm) | 0.756" (19.19 mm) | 0.752" (19.09 mm) | 0.748" (18.99 mm) | 0.743" (18.88 mm) |
| 13 ⁄16 - 20 20-UN | 0.777" (19.73 mm) | 0.774" (19.65 mm) | 0.77" (19.57 mm) | 0.767" (19.48 mm) | 0.764" (19.4 mm) | 0.761" (19.32 mm) | 0.757" (19.24 mm) |
| 13 ⁄16 - 28 28-UN | 0.787" (19.99 mm) | 0.785" (19.93 mm) | 0.782" (19.87 mm) | 0.78" (19.81 mm) | 0.778" (19.75 mm) | 0.775" (19.69 mm) | 0.773" (19.64 mm) |
| 13 ⁄16 - 32 32-UN | 0.79" (20.07 mm) | 0.788" (20.02 mm) | 0.786" (19.97 mm) | 0.784" (19.92 mm) | 0.782" (19.86 mm) | 0.78" (19.81 mm) | 0.778" (19.76 mm) |
| 7 ⁄8 - 9 UNC | 0.796" (20.21 mm) | 0.788" (20.03 mm) | 0.781" (19.84 mm) | 0.774" (19.66 mm) | 0.767" (19.48 mm) | 0.76" (19.29 mm) | 0.752" (19.11 mm) |
| 7 ⁄8 - 14 UNF | 0.824" (20.93 mm) | 0.819" (20.81 mm) | 0.815" (20.69 mm) | 0.81" (20.58 mm) | 0.805" (20.46 mm) | 0.801" (20.34 mm) | 0.796" (20.22 mm) |
| 7 ⁄8 - 20 UNEF | 0.839" (21.32 mm) | 0.836" (21.24 mm) | 0.833" (21.15 mm) | 0.83" (21.07 mm) | 0.826" (20.99 mm) | 0.823" (20.91 mm) | 0.82" (20.82 mm) |
| 7 ⁄8 - 12 12-UN | 0.815" (20.71 mm) | 0.81" (20.58 mm) | 0.805" (20.44 mm) | 0.799" (20.3 mm) | 0.794" (20.16 mm) | 0.788" (20.03 mm) | 0.783" (19.89 mm) |
| 7 ⁄8 - 16 16-UN | 0.83" (21.09 mm) | 0.826" (20.99 mm) | 0.822" (20.88 mm) | 0.818" (20.78 mm) | 0.814" (20.68 mm) | 0.81" (20.58 mm) | 0.806" (20.47 mm) |
| 7 ⁄8 - 20 20-UN | 0.839" (21.32 mm) | 0.836" (21.24 mm) | 0.833" (21.15 mm) | 0.83" (21.07 mm) | 0.826" (20.99 mm) | 0.823" (20.91 mm) | 0.82" (20.82 mm) |
| 7 ⁄8 - 28 28-UN | 0.849" (21.58 mm) | 0.847" (21.52 mm) | 0.845" (21.46 mm) | 0.843" (21.4 mm) | 0.84" (21.34 mm) | 0.838" (21.28 mm) | 0.836" (21.22 mm) |
| 7 ⁄8 - 32 32-UN | 0.853" (21.66 mm) | 0.851" (21.61 mm) | 0.849" (21.55 mm) | 0.847" (21.5 mm) | 0.845" (21.45 mm) | 0.843" (21.4 mm) | 0.84" (21.35 mm) |
| 15 ⁄16 - 20 UNEF | 0.902" (22.91 mm) | 0.899" (22.82 mm) | 0.895" (22.74 mm) | 0.892" (22.66 mm) | 0.889" (22.58 mm) | 0.886" (22.49 mm) | 0.882" (22.41 mm) |
| 15 ⁄16 - 12 12-UN | 0.878" (22.3 mm) | 0.873" (22.16 mm) | 0.867" (22.03 mm) | 0.862" (21.89 mm) | 0.856" (21.75 mm) | 0.851" (21.61 mm) | 0.845" (21.48 mm) |
| 15 ⁄16 - 16 16-UN | 0.893" (22.68 mm) | 0.889" (22.58 mm) | 0.885" (22.47 mm) | 0.881" (22.37 mm) | 0.877" (22.27 mm) | 0.873" (22.16 mm) | 0.868" (22.06 mm) |
| 15 ⁄16 - 20 20-UN | 0.902" (22.91 mm) | 0.899" (22.82 mm) | 0.895" (22.74 mm) | 0.892" (22.66 mm) | 0.889" (22.58 mm) | 0.886" (22.49 mm) | 0.882" (22.41 mm) |
| 15 ⁄16 - 28 28-UN | 0.912" (23.16 mm) | 0.91" (23.11 mm) | 0.907" (23.05 mm) | 0.905" (22.99 mm) | 0.903" (22.93 mm) | 0.9" (22.87 mm) | 0.898" (22.81 mm) |
| 15 ⁄16 - 32 32-UN | 0.915" (23.25 mm) | 0.913" (23.19 mm) | 0.911" (23.14 mm) | 0.909" (23.09 mm) | 0.907" (23.04 mm) | 0.905" (22.99 mm) | 0.903" (22.94 mm) |
| 1 - 8 UNC | 0.911" (23.13 mm) | 0.903" (22.93 mm) | 0.894" (22.72 mm) | 0.886" (22.51 mm) | 0.878" (22.31 mm) | 0.87" (22.1 mm) | 0.862" (21.89 mm) |
| 1 - 12 UNF | 0.94" (23.89 mm) | 0.935" (23.75 mm) | 0.93" (23.61 mm) | 0.924" (23.48 mm) | 0.919" (23.34 mm) | 0.913" (23.2 mm) | 0.908" (23.06 mm) |
| 1 - 20 UNEF | 0.964" (24.49 mm) | 0.961" (24.41 mm) | 0.958" (24.33 mm) | 0.955" (24.25 mm) | 0.951" (24.16 mm) | 0.948" (24.08 mm) | 0.945" (24. mm) |
| 1 - 8 8-UN | 0.911" (23.13 mm) | 0.903" (22.93 mm) | 0.894" (22.72 mm) | 0.886" (22.51 mm) | 0.878" (22.31 mm) | 0.87" (22.1 mm) | 0.862" (21.89 mm) |
| 1 - 12 12-UN | 0.94" (23.89 mm) | 0.935" (23.75 mm) | 0.93" (23.61 mm) | 0.924" (23.48 mm) | 0.919" (23.34 mm) | 0.913" (23.2 mm) | 0.908" (23.06 mm) |
| 1 - 16 16-UN | 0.955" (24.27 mm) | 0.951" (24.16 mm) | 0.947" (24.06 mm) | 0.943" (23.96 mm) | 0.939" (23.85 mm) | 0.935" (23.75 mm) | 0.931" (23.65 mm) |
| 1 - 20 20-UN | 0.964" (24.49 mm) | 0.961" (24.41 mm) | 0.958" (24.33 mm) | 0.955" (24.25 mm) | 0.951" (24.16 mm) | 0.948" (24.08 mm) | 0.945" (24. mm) |
| 1 - 28 28-UN | 0.974" (24.75 mm) | 0.972" (24.69 mm) | 0.97" (24.63 mm) | 0.968" (24.58 mm) | 0.965" (24.52 mm) | 0.963" (24.46 mm) | 0.961" (24.4 mm) |
| 1 - 32 32-UN | 0.978" (24.83 mm) | 0.976" (24.78 mm) | 0.974" (24.73 mm) | 0.972" (24.68 mm) | 0.97" (24.63 mm) | 0.968" (24.58 mm) | 0.965" (24.52 mm) |
Metric Threads Tap Drill Size Chart
Tap Drill size per thread height (In percentage)
- Press ⊕ to view all Width (55%-85%).
| Thread | 55% (Width) | 60% | 65% | 70% | 75% | 80% | 85% |
|---|---|---|---|---|---|---|---|
| #0 - 80 UNF | 0.051" (1.3 mm) | 0.05" (1.28 mm) | 0.049" (1.26 mm) | 0.049" (1.24 mm) | 0.048" (1.21 mm) | 0.047" (1.19 mm) | 0.046" (1.17 mm) |
| #1 - 64 UNC | 0.062" (1.57 mm) | 0.061" (1.54 mm) | 0.06" (1.52 mm) | 0.059" (1.49 mm) | 0.058" (1.47 mm) | 0.057" (1.44 mm) | 0.056" (1.42 mm) |
| #1 - 72 UNF | 0.063" (1.6 mm) | 0.062" (1.58 mm) | 0.061" (1.56 mm) | 0.06" (1.53 mm) | 0.059" (1.51 mm) | 0.059" (1.49 mm) | 0.058" (1.46 mm) |
| #2 - 56 UNC | 0.073" (1.86 mm) | 0.072" (1.83 mm) | 0.071" (1.8 mm) | 0.07" (1.77 mm) | 0.069" (1.74 mm) | 0.067" (1.71 mm) | 0.066" (1.68 mm) |
| #2 - 64 UNF | 0.075" (1.9 mm) | 0.074" (1.88 mm) | 0.073" (1.85 mm) | 0.072" (1.82 mm) | 0.071" (1.8 mm) | 0.07" (1.77 mm) | 0.069" (1.75 mm) |
| #3 - 48 UNC | 0.084" (2.14 mm) | 0.083" (2.1 mm) | 0.081" (2.07 mm) | 0.08" (2.03 mm) | 0.079" (2. mm) | 0.077" (1.96 mm) | 0.076" (1.93 mm) |
| #3 - 56 UNF | 0.086" (2.19 mm) | 0.085" (2.16 mm) | 0.084" (2.13 mm) | 0.083" (2.1 mm) | 0.082" (2.07 mm) | 0.08" (2.04 mm) | 0.079" (2.01 mm) |
| #4 - 40 UNC | 0.094" (2.39 mm) | 0.093" (2.35 mm) | 0.091" (2.31 mm) | 0.089" (2.27 mm) | 0.088" (2.23 mm) | 0.086" (2.18 mm) | 0.084" (2.14 mm) |
| #4 - 48 UNF | 0.097" (2.47 mm) | 0.096" (2.43 mm) | 0.094" (2.4 mm) | 0.093" (2.36 mm) | 0.092" (2.33 mm) | 0.09" (2.29 mm) | 0.089" (2.26 mm) |
| #5 - 40 UNC | 0.107" (2.72 mm) | 0.106" (2.68 mm) | 0.104" (2.64 mm) | 0.102" (2.6 mm) | 0.101" (2.56 mm) | 0.099" (2.52 mm) | 0.097" (2.47 mm) |
| #5 - 44 UNF | 0.109" (2.76 mm) | 0.107" (2.73 mm) | 0.106" (2.69 mm) | 0.104" (2.65 mm) | 0.103" (2.61 mm) | 0.101" (2.58 mm) | 0.1" (2.54 mm) |
| #6 - 32 UNC | 0.116" (2.94 mm) | 0.114" (2.89 mm) | 0.112" (2.83 mm) | 0.11" (2.78 mm) | 0.108" (2.73 mm) | 0.106" (2.68 mm) | 0.103" (2.63 mm) |
| #6 - 40 UNF | 0.12" (3.05 mm) | 0.119" (3.01 mm) | 0.117" (2.97 mm) | 0.115" (2.93 mm) | 0.114" (2.89 mm) | 0.112" (2.85 mm) | 0.11" (2.8 mm) |
| #6 - 32 32-UN | 0.116" (2.94 mm) | 0.114" (2.89 mm) | 0.112" (2.83 mm) | 0.11" (2.78 mm) | 0.108" (2.73 mm) | 0.106" (2.68 mm) | 0.103" (2.63 mm) |
| #8 - 32 UNC | 0.142" (3.6 mm) | 0.14" (3.55 mm) | 0.138" (3.5 mm) | 0.136" (3.44 mm) | 0.134" (3.39 mm) | 0.132" (3.34 mm) | 0.129" (3.29 mm) |
| #8 - 36 UNF | 0.144" (3.66 mm) | 0.142" (3.62 mm) | 0.141" (3.57 mm) | 0.139" (3.52 mm) | 0.137" (3.48 mm) | 0.135" (3.43 mm) | 0.133" (3.39 mm) |
| #8 - 32 32-UN | 0.142" (3.6 mm) | 0.14" (3.55 mm) | 0.138" (3.5 mm) | 0.136" (3.44 mm) | 0.134" (3.39 mm) | 0.132" (3.34 mm) | 0.129" (3.29 mm) |
| #10 - 24 UNC | 0.16" (4.07 mm) | 0.158" (4. mm) | 0.155" (3.93 mm) | 0.152" (3.86 mm) | 0.149" (3.79 mm) | 0.147" (3.73 mm) | 0.144" (3.66 mm) |
| #10 - 32 UNF | 0.168" (4.26 mm) | 0.166" (4.21 mm) | 0.164" (4.16 mm) | 0.162" (4.1 mm) | 0.16" (4.05 mm) | 0.158" (4. mm) | 0.155" (3.95 mm) |
| #10 - 32 32-UN | 0.168" (4.26 mm) | 0.166" (4.21 mm) | 0.164" (4.16 mm) | 0.162" (4.1 mm) | 0.16" (4.05 mm) | 0.158" (4. mm) | 0.155" (3.95 mm) |
| #12 - 24 UNC | 0.186" (4.73 mm) | 0.184" (4.66 mm) | 0.181" (4.59 mm) | 0.178" (4.52 mm) | 0.175" (4.46 mm) | 0.173" (4.39 mm) | 0.17" (4.32 mm) |
| #12 - 28 UNF | 0.19" (4.84 mm) | 0.188" (4.78 mm) | 0.186" (4.72 mm) | 0.184" (4.66 mm) | 0.181" (4.6 mm) | 0.179" (4.54 mm) | 0.177" (4.48 mm) |
| #12 - 32 UNEF | 0.194" (4.92 mm) | 0.192" (4.87 mm) | 0.19" (4.82 mm) | 0.188" (4.76 mm) | 0.186" (4.71 mm) | 0.184" (4.66 mm) | 0.181" (4.61 mm) |
| #12 - 28 28-UN | 0.19" (4.84 mm) | 0.188" (4.78 mm) | 0.186" (4.72 mm) | 0.184" (4.66 mm) | 0.181" (4.6 mm) | 0.179" (4.54 mm) | 0.177" (4.48 mm) |
| #12 - 32 32-UN | 0.194" (4.92 mm) | 0.192" (4.87 mm) | 0.19" (4.82 mm) | 0.188" (4.76 mm) | 0.186" (4.71 mm) | 0.184" (4.66 mm) | 0.181" (4.61 mm) |
| 1 ⁄4 - 20 UNC | 0.214" (5.44 mm) | 0.211" (5.36 mm) | 0.208" (5.28 mm) | 0.205" (5.2 mm) | 0.201" (5.11 mm) | 0.198" (5.03 mm) | 0.195" (4.95 mm) |
| 1 ⁄4 - 28 UNF | 0.224" (5.7 mm) | 0.222" (5.64 mm) | 0.22" (5.58 mm) | 0.218" (5.53 mm) | 0.215" (5.47 mm) | 0.213" (5.41 mm) | 0.211" (5.35 mm) |
| 1 ⁄4 - 32 UNEF | 0.228" (5.78 mm) | 0.226" (5.73 mm) | 0.224" (5.68 mm) | 0.222" (5.63 mm) | 0.22" (5.58 mm) | 0.218" (5.53 mm) | 0.215" (5.47 mm) |
| 1 ⁄4 - 20 20-UN | 0.214" (5.44 mm) | 0.211" (5.36 mm) | 0.208" (5.28 mm) | 0.205" (5.2 mm) | 0.201" (5.11 mm) | 0.198" (5.03 mm) | 0.195" (4.95 mm) |
| 1 ⁄4 - 28 28-UN | 0.224" (5.7 mm) | 0.222" (5.64 mm) | 0.22" (5.58 mm) | 0.218" (5.53 mm) | 0.215" (5.47 mm) | 0.213" (5.41 mm) | 0.211" (5.35 mm) |
| 1 ⁄4 - 32 32-UN | 0.228" (5.78 mm) | 0.226" (5.73 mm) | 0.224" (5.68 mm) | 0.222" (5.63 mm) | 0.22" (5.58 mm) | 0.218" (5.53 mm) | 0.215" (5.47 mm) |
| 5 ⁄16 - 18 UNC | 0.273" (6.93 mm) | 0.269" (6.84 mm) | 0.266" (6.75 mm) | 0.262" (6.65 mm) | 0.258" (6.56 mm) | 0.255" (6.47 mm) | 0.251" (6.38 mm) |
| 5 ⁄16 - 24 UNF | 0.283" (7.18 mm) | 0.28" (7.11 mm) | 0.277" (7.04 mm) | 0.275" (6.98 mm) | 0.272" (6.91 mm) | 0.269" (6.84 mm) | 0.266" (6.77 mm) |
| 5 ⁄16 - 32 UNEF | 0.29" (7.37 mm) | 0.288" (7.32 mm) | 0.286" (7.27 mm) | 0.284" (7.22 mm) | 0.282" (7.16 mm) | 0.28" (7.11 mm) | 0.278" (7.06 mm) |
| 5 ⁄16 - 20 20-UN | 0.277" (7.03 mm) | 0.274" (6.95 mm) | 0.27" (6.87 mm) | 0.267" (6.78 mm) | 0.264" (6.7 mm) | 0.261" (6.62 mm) | 0.257" (6.54 mm) |
| 5 ⁄16 - 28 28-UN | 0.287" (7.29 mm) | 0.285" (7.23 mm) | 0.282" (7.17 mm) | 0.28" (7.11 mm) | 0.278" (7.05 mm) | 0.275" (6.99 mm) | 0.273" (6.94 mm) |
| 5 ⁄16 - 32 32-UN | 0.29" (7.37 mm) | 0.288" (7.32 mm) | 0.286" (7.27 mm) | 0.284" (7.22 mm) | 0.282" (7.16 mm) | 0.28" (7.11 mm) | 0.278" (7.06 mm) |
| 3 ⁄8 - 16 UNC | 0.33" (8.39 mm) | 0.326" (8.29 mm) | 0.322" (8.18 mm) | 0.318" (8.08 mm) | 0.314" (7.98 mm) | 0.31" (7.88 mm) | 0.306" (7.77 mm) |
| 3 ⁄8 - 24 UNF | 0.345" (8.77 mm) | 0.343" (8.7 mm) | 0.34" (8.63 mm) | 0.337" (8.56 mm) | 0.334" (8.49 mm) | 0.332" (8.43 mm) | 0.329" (8.36 mm) |
| 3 ⁄8 - 32 UNEF | 0.353" (8.96 mm) | 0.351" (8.91 mm) | 0.349" (8.85 mm) | 0.347" (8.8 mm) | 0.345" (8.75 mm) | 0.343" (8.7 mm) | 0.34" (8.65 mm) |
| 3 ⁄8 - 16 16-UN | 0.33" (8.39 mm) | 0.326" (8.29 mm) | 0.322" (8.18 mm) | 0.318" (8.08 mm) | 0.314" (7.98 mm) | 0.31" (7.88 mm) | 0.306" (7.77 mm) |
| 3 ⁄8 - 20 20-UN | 0.339" (8.62 mm) | 0.336" (8.54 mm) | 0.333" (8.45 mm) | 0.33" (8.37 mm) | 0.326" (8.29 mm) | 0.323" (8.21 mm) | 0.32" (8.12 mm) |
| 3 ⁄8 - 28 28-UN | 0.349" (8.88 mm) | 0.347" (8.82 mm) | 0.345" (8.76 mm) | 0.343" (8.7 mm) | 0.34" (8.64 mm) | 0.338" (8.58 mm) | 0.336" (8.52 mm) |
| 3 ⁄8 - 32 32-UN | 0.353" (8.96 mm) | 0.351" (8.91 mm) | 0.349" (8.85 mm) | 0.347" (8.8 mm) | 0.345" (8.75 mm) | 0.343" (8.7 mm) | 0.34" (8.65 mm) |
| 7 ⁄16 - 14 UNC | 0.386" (9.82 mm) | 0.382" (9.7 mm) | 0.377" (9.58 mm) | 0.373" (9.46 mm) | 0.368" (9.34 mm) | 0.363" (9.23 mm) | 0.359" (9.11 mm) |
| 7 ⁄16 - 20 UNF | 0.402" (10.21 mm) | 0.399" (10.12 mm) | 0.395" (10.04 mm) | 0.392" (9.96 mm) | 0.389" (9.88 mm) | 0.386" (9.79 mm) | 0.382" (9.71 mm) |
| 7 ⁄16 - 28 UNEF | 0.412" (10.46 mm) | 0.41" (10.41 mm) | 0.407" (10.35 mm) | 0.405" (10.29 mm) | 0.403" (10.23 mm) | 0.4" (10.17 mm) | 0.398" (10.11 mm) |
| 7 ⁄16 - 16 16-UN | 0.393" (9.98 mm) | 0.389" (9.88 mm) | 0.385" (9.77 mm) | 0.381" (9.67 mm) | 0.377" (9.57 mm) | 0.373" (9.46 mm) | 0.368" (9.36 mm) |
| 7 ⁄16 - 20 20-UN | 0.402" (10.21 mm) | 0.399" (10.12 mm) | 0.395" (10.04 mm) | 0.392" (9.96 mm) | 0.389" (9.88 mm) | 0.386" (9.79 mm) | 0.382" (9.71 mm) |
| 7 ⁄16 - 28 28-UN | 0.412" (10.46 mm) | 0.41" (10.41 mm) | 0.407" (10.35 mm) | 0.405" (10.29 mm) | 0.403" (10.23 mm) | 0.4" (10.17 mm) | 0.398" (10.11 mm) |
| 7 ⁄16 - 32 32-UN | 0.415" (10.55 mm) | 0.413" (10.49 mm) | 0.411" (10.44 mm) | 0.409" (10.39 mm) | 0.407" (10.34 mm) | 0.405" (10.29 mm) | 0.403" (10.24 mm) |
| 1 ⁄2 - 13 UNC | 0.445" (11.3 mm) | 0.44" (11.18 mm) | 0.435" (11.05 mm) | 0.43" (10.92 mm) | 0.425" (10.8 mm) | 0.42" (10.67 mm) | 0.415" (10.54 mm) |
| 1 ⁄2 - 20 UNF | 0.464" (11.79 mm) | 0.461" (11.71 mm) | 0.458" (11.63 mm) | 0.455" (11.55 mm) | 0.451" (11.46 mm) | 0.448" (11.38 mm) | 0.445" (11.3 mm) |
| 1 ⁄2 - 28 UNEF | 0.474" (12.05 mm) | 0.472" (11.99 mm) | 0.47" (11.93 mm) | 0.468" (11.88 mm) | 0.465" (11.82 mm) | 0.463" (11.76 mm) | 0.461" (11.7 mm) |
| 1 ⁄2 - 16 16-UN | 0.455" (11.57 mm) | 0.451" (11.46 mm) | 0.447" (11.36 mm) | 0.443" (11.26 mm) | 0.439" (11.15 mm) | 0.435" (11.05 mm) | 0.431" (10.95 mm) |
| 1 ⁄2 - 20 20-UN | 0.464" (11.79 mm) | 0.461" (11.71 mm) | 0.458" (11.63 mm) | 0.455" (11.55 mm) | 0.451" (11.46 mm) | 0.448" (11.38 mm) | 0.445" (11.3 mm) |
| 1 ⁄2 - 28 28-UN | 0.474" (12.05 mm) | 0.472" (11.99 mm) | 0.47" (11.93 mm) | 0.468" (11.88 mm) | 0.465" (11.82 mm) | 0.463" (11.76 mm) | 0.461" (11.7 mm) |
| 1 ⁄2 - 32 32-UN | 0.478" (12.13 mm) | 0.476" (12.08 mm) | 0.474" (12.03 mm) | 0.472" (11.98 mm) | 0.47" (11.93 mm) | 0.468" (11.88 mm) | 0.465" (11.82 mm) |
| 9 ⁄16 - 12 UNC | 0.503" (12.78 mm) | 0.498" (12.64 mm) | 0.492" (12.5 mm) | 0.487" (12.36 mm) | 0.481" (12.23 mm) | 0.476" (12.09 mm) | 0.47" (11.95 mm) |
| 9 ⁄16 - 18 UNF | 0.523" (13.28 mm) | 0.519" (13.19 mm) | 0.516" (13.1 mm) | 0.512" (13. mm) | 0.508" (12.91 mm) | 0.505" (12.82 mm) | 0.501" (12.73 mm) |
| 9 ⁄16 - 24 UNEF | 0.533" (13.53 mm) | 0.53" (13.46 mm) | 0.527" (13.39 mm) | 0.525" (13.33 mm) | 0.522" (13.26 mm) | 0.519" (13.19 mm) | 0.516" (13.12 mm) |
| 9 ⁄16 - 12 12-UN | 0.503" (12.78 mm) | 0.498" (12.64 mm) | 0.492" (12.5 mm) | 0.487" (12.36 mm) | 0.481" (12.23 mm) | 0.476" (12.09 mm) | 0.47" (11.95 mm) |
| 9 ⁄16 - 16 16-UN | 0.518" (13.15 mm) | 0.514" (13.05 mm) | 0.51" (12.95 mm) | 0.506" (12.84 mm) | 0.502" (12.74 mm) | 0.498" (12.64 mm) | 0.493" (12.53 mm) |
| 9 ⁄16 - 20 20-UN | 0.527" (13.38 mm) | 0.524" (13.3 mm) | 0.52" (13.22 mm) | 0.517" (13.13 mm) | 0.514" (13.05 mm) | 0.511" (12.97 mm) | 0.507" (12.89 mm) |
| 9 ⁄16 - 28 28-UN | 0.537" (13.64 mm) | 0.535" (13.58 mm) | 0.532" (13.52 mm) | 0.53" (13.46 mm) | 0.528" (13.4 mm) | 0.525" (13.34 mm) | 0.523" (13.29 mm) |
| 9 ⁄16 - 32 32-UN | 0.54" (13.72 mm) | 0.538" (13.67 mm) | 0.536" (13.62 mm) | 0.534" (13.57 mm) | 0.532" (13.51 mm) | 0.53" (13.46 mm) | 0.528" (13.41 mm) |
| 5 ⁄8 - 11 UNC | 0.56" (14.23 mm) | 0.554" (14.08 mm) | 0.548" (13.93 mm) | 0.542" (13.78 mm) | 0.536" (13.63 mm) | 0.531" (13.48 mm) | 0.525" (13.33 mm) |
| 5 ⁄8 - 18 UNF | 0.585" (14.87 mm) | 0.582" (14.78 mm) | 0.578" (14.68 mm) | 0.574" (14.59 mm) | 0.571" (14.5 mm) | 0.567" (14.41 mm) | 0.564" (14.32 mm) |
| 5 ⁄8 - 24 UNEF | 0.595" (15.12 mm) | 0.593" (15.05 mm) | 0.59" (14.98 mm) | 0.587" (14.91 mm) | 0.584" (14.84 mm) | 0.582" (14.78 mm) | 0.579" (14.71 mm) |
| 5 ⁄8 - 12 12-UN | 0.565" (14.36 mm) | 0.56" (14.23 mm) | 0.555" (14.09 mm) | 0.549" (13.95 mm) | 0.544" (13.81 mm) | 0.538" (13.68 mm) | 0.533" (13.54 mm) |
| 5 ⁄8 - 16 16-UN | 0.58" (14.74 mm) | 0.576" (14.64 mm) | 0.572" (14.53 mm) | 0.568" (14.43 mm) | 0.564" (14.33 mm) | 0.56" (14.23 mm) | 0.556" (14.12 mm) |
| 5 ⁄8 - 20 20-UN | 0.589" (14.97 mm) | 0.586" (14.89 mm) | 0.583" (14.8 mm) | 0.58" (14.72 mm) | 0.576" (14.64 mm) | 0.573" (14.56 mm) | 0.57" (14.47 mm) |
| 5 ⁄8 - 28 28-UN | 0.599" (15.23 mm) | 0.597" (15.17 mm) | 0.595" (15.11 mm) | 0.593" (15.05 mm) | 0.59" (14.99 mm) | 0.588" (14.93 mm) | 0.586" (14.87 mm) |
| 5 ⁄8 - 32 32-UN | 0.603" (15.31 mm) | 0.601" (15.26 mm) | 0.599" (15.2 mm) | 0.597" (15.15 mm) | 0.595" (15.1 mm) | 0.593" (15.05 mm) | 0.59" (15. mm) |
| 11 ⁄16 - 24 UNEF | 0.658" (16.71 mm) | 0.655" (16.64 mm) | 0.652" (16.57 mm) | 0.65" (16.5 mm) | 0.647" (16.43 mm) | 0.644" (16.36 mm) | 0.641" (16.29 mm) |
| 11 ⁄16 - 12 12-UN | 0.628" (15.95 mm) | 0.623" (15.81 mm) | 0.617" (15.68 mm) | 0.612" (15.54 mm) | 0.606" (15.4 mm) | 0.601" (15.26 mm) | 0.595" (15.13 mm) |
| 11 ⁄16 - 16 16-UN | 0.643" (16.33 mm) | 0.639" (16.23 mm) | 0.635" (16.12 mm) | 0.631" (16.02 mm) | 0.627" (15.92 mm) | 0.623" (15.81 mm) | 0.618" (15.71 mm) |
| 11 ⁄16 - 20 20-UN | 0.652" (16.56 mm) | 0.649" (16.47 mm) | 0.645" (16.39 mm) | 0.642" (16.31 mm) | 0.639" (16.23 mm) | 0.636" (16.14 mm) | 0.632" (16.06 mm) |
| 11 ⁄16 - 28 28-UN | 0.662" (16.81 mm) | 0.66" (16.76 mm) | 0.657" (16.7 mm) | 0.655" (16.64 mm) | 0.653" (16.58 mm) | 0.65" (16.52 mm) | 0.648" (16.46 mm) |
| 11 ⁄16 - 32 32-UN | 0.665" (16.9 mm) | 0.663" (16.84 mm) | 0.661" (16.79 mm) | 0.659" (16.74 mm) | 0.657" (16.69 mm) | 0.655" (16.64 mm) | 0.653" (16.59 mm) |
| 3 ⁄4 - 10 UNC | 0.679" (17.24 mm) | 0.672" (17.07 mm) | 0.666" (16.91 mm) | 0.659" (16.74 mm) | 0.653" (16.58 mm) | 0.646" (16.41 mm) | 0.64" (16.25 mm) |
| 3 ⁄4 - 16 UNF | 0.705" (17.92 mm) | 0.701" (17.81 mm) | 0.697" (17.71 mm) | 0.693" (17.61 mm) | 0.689" (17.5 mm) | 0.685" (17.4 mm) | 0.681" (17.3 mm) |
| 3 ⁄4 - 20 UNEF | 0.714" (18.14 mm) | 0.711" (18.06 mm) | 0.708" (17.98 mm) | 0.705" (17.9 mm) | 0.701" (17.81 mm) | 0.698" (17.73 mm) | 0.695" (17.65 mm) |
| 3 ⁄4 - 12 12-UN | 0.69" (17.54 mm) | 0.685" (17.4 mm) | 0.68" (17.26 mm) | 0.674" (17.13 mm) | 0.669" (16.99 mm) | 0.663" (16.85 mm) | 0.658" (16.71 mm) |
| 3 ⁄4 - 16 16-UN | 0.705" (17.92 mm) | 0.701" (17.81 mm) | 0.697" (17.71 mm) | 0.693" (17.61 mm) | 0.689" (17.5 mm) | 0.685" (17.4 mm) | 0.681" (17.3 mm) |
| 3 ⁄4 - 20 20-UN | 0.714" (18.14 mm) | 0.711" (18.06 mm) | 0.708" (17.98 mm) | 0.705" (17.9 mm) | 0.701" (17.81 mm) | 0.698" (17.73 mm) | 0.695" (17.65 mm) |
| 3 ⁄4 - 28 28-UN | 0.724" (18.4 mm) | 0.722" (18.34 mm) | 0.72" (18.28 mm) | 0.718" (18.23 mm) | 0.715" (18.17 mm) | 0.713" (18.11 mm) | 0.711" (18.05 mm) |
| 3 ⁄4 - 32 32-UN | 0.728" (18.48 mm) | 0.726" (18.43 mm) | 0.724" (18.38 mm) | 0.722" (18.33 mm) | 0.72" (18.28 mm) | 0.718" (18.23 mm) | 0.715" (18.17 mm) |
| 13 ⁄16 - 20 UNEF | 0.777" (19.73 mm) | 0.774" (19.65 mm) | 0.77" (19.57 mm) | 0.767" (19.48 mm) | 0.764" (19.4 mm) | 0.761" (19.32 mm) | 0.757" (19.24 mm) |
| 13 ⁄16 - 12 12-UN | 0.753" (19.13 mm) | 0.748" (18.99 mm) | 0.742" (18.85 mm) | 0.737" (18.71 mm) | 0.731" (18.58 mm) | 0.726" (18.44 mm) | 0.72" (18.3 mm) |
| 13 ⁄16 - 16 16-UN | 0.768" (19.5 mm) | 0.764" (19.4 mm) | 0.76" (19.3 mm) | 0.756" (19.19 mm) | 0.752" (19.09 mm) | 0.748" (18.99 mm) | 0.743" (18.88 mm) |
| 13 ⁄16 - 20 20-UN | 0.777" (19.73 mm) | 0.774" (19.65 mm) | 0.77" (19.57 mm) | 0.767" (19.48 mm) | 0.764" (19.4 mm) | 0.761" (19.32 mm) | 0.757" (19.24 mm) |
| 13 ⁄16 - 28 28-UN | 0.787" (19.99 mm) | 0.785" (19.93 mm) | 0.782" (19.87 mm) | 0.78" (19.81 mm) | 0.778" (19.75 mm) | 0.775" (19.69 mm) | 0.773" (19.64 mm) |
| 13 ⁄16 - 32 32-UN | 0.79" (20.07 mm) | 0.788" (20.02 mm) | 0.786" (19.97 mm) | 0.784" (19.92 mm) | 0.782" (19.86 mm) | 0.78" (19.81 mm) | 0.778" (19.76 mm) |
| 7 ⁄8 - 9 UNC | 0.796" (20.21 mm) | 0.788" (20.03 mm) | 0.781" (19.84 mm) | 0.774" (19.66 mm) | 0.767" (19.48 mm) | 0.76" (19.29 mm) | 0.752" (19.11 mm) |
| 7 ⁄8 - 14 UNF | 0.824" (20.93 mm) | 0.819" (20.81 mm) | 0.815" (20.69 mm) | 0.81" (20.58 mm) | 0.805" (20.46 mm) | 0.801" (20.34 mm) | 0.796" (20.22 mm) |
| 7 ⁄8 - 20 UNEF | 0.839" (21.32 mm) | 0.836" (21.24 mm) | 0.833" (21.15 mm) | 0.83" (21.07 mm) | 0.826" (20.99 mm) | 0.823" (20.91 mm) | 0.82" (20.82 mm) |
| 7 ⁄8 - 12 12-UN | 0.815" (20.71 mm) | 0.81" (20.58 mm) | 0.805" (20.44 mm) | 0.799" (20.3 mm) | 0.794" (20.16 mm) | 0.788" (20.03 mm) | 0.783" (19.89 mm) |
| 7 ⁄8 - 16 16-UN | 0.83" (21.09 mm) | 0.826" (20.99 mm) | 0.822" (20.88 mm) | 0.818" (20.78 mm) | 0.814" (20.68 mm) | 0.81" (20.58 mm) | 0.806" (20.47 mm) |
| 7 ⁄8 - 20 20-UN | 0.839" (21.32 mm) | 0.836" (21.24 mm) | 0.833" (21.15 mm) | 0.83" (21.07 mm) | 0.826" (20.99 mm) | 0.823" (20.91 mm) | 0.82" (20.82 mm) |
| 7 ⁄8 - 28 28-UN | 0.849" (21.58 mm) | 0.847" (21.52 mm) | 0.845" (21.46 mm) | 0.843" (21.4 mm) | 0.84" (21.34 mm) | 0.838" (21.28 mm) | 0.836" (21.22 mm) |
| 7 ⁄8 - 32 32-UN | 0.853" (21.66 mm) | 0.851" (21.61 mm) | 0.849" (21.55 mm) | 0.847" (21.5 mm) | 0.845" (21.45 mm) | 0.843" (21.4 mm) | 0.84" (21.35 mm) |
| 15 ⁄16 - 20 UNEF | 0.902" (22.91 mm) | 0.899" (22.82 mm) | 0.895" (22.74 mm) | 0.892" (22.66 mm) | 0.889" (22.58 mm) | 0.886" (22.49 mm) | 0.882" (22.41 mm) |
| 15 ⁄16 - 12 12-UN | 0.878" (22.3 mm) | 0.873" (22.16 mm) | 0.867" (22.03 mm) | 0.862" (21.89 mm) | 0.856" (21.75 mm) | 0.851" (21.61 mm) | 0.845" (21.48 mm) |
| 15 ⁄16 - 16 16-UN | 0.893" (22.68 mm) | 0.889" (22.58 mm) | 0.885" (22.47 mm) | 0.881" (22.37 mm) | 0.877" (22.27 mm) | 0.873" (22.16 mm) | 0.868" (22.06 mm) |
| 15 ⁄16 - 20 20-UN | 0.902" (22.91 mm) | 0.899" (22.82 mm) | 0.895" (22.74 mm) | 0.892" (22.66 mm) | 0.889" (22.58 mm) | 0.886" (22.49 mm) | 0.882" (22.41 mm) |
| 15 ⁄16 - 28 28-UN | 0.912" (23.16 mm) | 0.91" (23.11 mm) | 0.907" (23.05 mm) | 0.905" (22.99 mm) | 0.903" (22.93 mm) | 0.9" (22.87 mm) | 0.898" (22.81 mm) |
| 15 ⁄16 - 32 32-UN | 0.915" (23.25 mm) | 0.913" (23.19 mm) | 0.911" (23.14 mm) | 0.909" (23.09 mm) | 0.907" (23.04 mm) | 0.905" (22.99 mm) | 0.903" (22.94 mm) |
| 1 - 8 UNC | 0.911" (23.13 mm) | 0.903" (22.93 mm) | 0.894" (22.72 mm) | 0.886" (22.51 mm) | 0.878" (22.31 mm) | 0.87" (22.1 mm) | 0.862" (21.89 mm) |
| 1 - 12 UNF | 0.94" (23.89 mm) | 0.935" (23.75 mm) | 0.93" (23.61 mm) | 0.924" (23.48 mm) | 0.919" (23.34 mm) | 0.913" (23.2 mm) | 0.908" (23.06 mm) |
| 1 - 20 UNEF | 0.964" (24.49 mm) | 0.961" (24.41 mm) | 0.958" (24.33 mm) | 0.955" (24.25 mm) | 0.951" (24.16 mm) | 0.948" (24.08 mm) | 0.945" (24. mm) |
| 1 - 8 8-UN | 0.911" (23.13 mm) | 0.903" (22.93 mm) | 0.894" (22.72 mm) | 0.886" (22.51 mm) | 0.878" (22.31 mm) | 0.87" (22.1 mm) | 0.862" (21.89 mm) |
| 1 - 12 12-UN | 0.94" (23.89 mm) | 0.935" (23.75 mm) | 0.93" (23.61 mm) | 0.924" (23.48 mm) | 0.919" (23.34 mm) | 0.913" (23.2 mm) | 0.908" (23.06 mm) |
| 1 - 16 16-UN | 0.955" (24.27 mm) | 0.951" (24.16 mm) | 0.947" (24.06 mm) | 0.943" (23.96 mm) | 0.939" (23.85 mm) | 0.935" (23.75 mm) | 0.931" (23.65 mm) |
| 1 - 20 20-UN | 0.964" (24.49 mm) | 0.961" (24.41 mm) | 0.958" (24.33 mm) | 0.955" (24.25 mm) | 0.951" (24.16 mm) | 0.948" (24.08 mm) | 0.945" (24. mm) |
| 1 - 28 28-UN | 0.974" (24.75 mm) | 0.972" (24.69 mm) | 0.97" (24.63 mm) | 0.968" (24.58 mm) | 0.965" (24.52 mm) | 0.963" (24.46 mm) | 0.961" (24.4 mm) |
| 1 - 32 32-UN | 0.978" (24.83 mm) | 0.976" (24.78 mm) | 0.974" (24.73 mm) | 0.972" (24.68 mm) | 0.97" (24.63 mm) | 0.968" (24.58 mm) | 0.965" (24.52 mm) |
Related Glossary Terms:
