11/16 - 24 UNEF - Basic Thread Dimensions

Property Inch mm
Nominal Diameter 0.687 17.45
Pitch (TPI)24
Pitch (Distance) 0.0417 1.059
Pitch Diameter 0.6599 16.761
Minor Diameter 0.6374 16.19
Thread Height 0.0226 0.574
Addendum 0.0135 0.343
Crest (External)
Root (Internal)		 0.0052 0.132
Tap Drill Size
(75% depth)		 0.646 16.42
Lead Angle
(Single Start)		 1.15°
Thread Family Unified Extra-Fine pitch (UNEF)
Relevant Standards ASME B1.1-2003
Equivalent Metric ThreadM18 X 1

For more threading data scroll down, or use the Thread Calculator

Table of Content

11/16 - 24 UNEF Possible Thread Classes

External Threads

Choose tolerance class: 2A, 3A

Metric ISO External Thread - Tolerance sketch

Internal Threads

Choose tolerance class: 2B, 3B

Metric ISO Internal Thread - Tolerance sketch

11/16 - 24 UNEF 2A (External)

* Permisable values for thread Class 2A

# Description Value (Inch) Value (mm)
es Allowance 0.0011 (Ref) 0.028 (Ref)
d Major Diameter 0.6787 - 0.6859 17.239 - 17.422
d2 Pitch Diameter 0.655 - 0.6588 16.637 - 16.734
d3 Minor Diameter
(UNR Only)		 0.6362 (Ref) 16.159 (Ref)
α Varation of 30° anngle (+/-) 1.25°
P Varation of pitch (+/-) 0.0011 (Ref) 0.028 (Ref)

* Values are calculated for Length of engagement of 5xPitch. For calculations of different engagement length use the Thread Calculator

* Back to Thread Class Selection

11/16 - 24 UNEF 3A (External)

* Permisable values for thread Class 3A

# Description Value (Inch) Value (mm)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 0.6798 - 0.687 17.267 - 17.45
d2 Pitch Diameter 0.657 - 0.6599 16.688 - 16.761
d3 Minor Diameter
(UNR Only)		 0.6374 (Ref) 16.19 (Ref)
α Varation of 30° anngle (+/-) 1.25°
P Varation of pitch (+/-) 0.0008 (Ref) 0.02 (Ref)

* Values are calculated for Length of engagement of 5xPitch. For calculations of different engagement length use the Thread Calculator

* Back to Thread Class Selection

11/16 - 24 UNEF 2B (Internal)

* Permisable values for thread Class 2B

# Description Value (Inch) Value (mm)
D1 Minor Diameter 0.642 - 0.652 16.307 - 16.561
D2 Pitch Diameter 0.6599 - 0.6649 16.761 - 16.888
D Major Diameter 0.6870 (Min) 17.45 (Min)
α Varation of 30° anngle (+/-) 1.25°
P Varation of Pitch (+/-) 0.0014 (Ref) 0.036 (Ref)

* Values are calculated for Length of engagement of 5xPitch. For calculations of different engagement length use the Thread Calculator

* Back to Thread Class Selection

11/16 - 24 UNEF 3B (Internal)

* Permisable values for thread Class 3B

# Description Value (Inch) Value (mm)
D1 Minor Diameter 0.6419 - 0.6489 16.304 - 16.482
D2 Pitch Diameter 0.6599 - 0.6636 16.761 - 16.855
D Major Diameter 0.6870 (Min) 17.45 (Min)
α Varation of 30° anngle (+/-) 1.25°
P Varation of Pitch (+/-) 0.0011 (Ref) 0.028 (Ref)

* Values are calculated for Length of engagement of 5xPitch. For calculations of different engagement length use the Thread Calculator

* Back to Thread Class Selection

Tap Drill Sizes for 11/16 - 24 UNEF

  • If not specified, assume a thread depth of 75%.
  • You can learn more about thread depth in tapping here.
  • To get the tap drill size in other depths, use our Tap Drill Size Calculator .
Thread Depth Tap Drill Size (Inch) Tap Drill Size (mm)
55% 0.657 16.69
60% 0.655 16.62
65% 0.652 16.56
70% 0.649 16.49
75% 0.646 16.42
80% 0.644 16.35
85% 0.641 16.28

Over Wire Measurements for 11/16 - 24 UNEF


* OverWire is a measuring method to obatin the pitch diameter of threads. It is mostly used when a manufacturer does not have a Go/Nogo gauge for a thread. You can learn more about it here

Inch mm
Permissible Wire Diameter Range 0.0211 - 0.0421 0.535 - 1.07
Ideal Wire Diameter 0.0241 0.612
Possible Wires
From Standard Sets		 * 0.0214
* 0.0222
* 0.0241
* 0.0262
* 0.0289
 * 0.577
* 0.722
* 0.866
* 1.01

Once you knoe your wire diameter, you need to find out what is the premissable Measurement for your pitch diameter (Depending on the class). Use our Over Wire Calculator to find out!


Scroll to Top