15/16 - 12 12-UN - Basic Thread Dimensions

Property Inch mm
Nominal Diameter 0.937 23.8
Pitch (TPI)12
Pitch (Distance) 0.0833 2.116
Pitch Diameter 0.8829 22.426
Minor Diameter 0.8378 21.28
Thread Height 0.0451 1.146
Addendum 0.0271 0.688
Crest (External)
Root (Internal)
0.0104 0.264
Tap Drill Size
(75% depth)
0.856 21.74
Lead Angle
(Single Start)
1.72°
Thread Family Unified Constant Pitch 6 TPI (12-UN)
Relevant Standards ASME B1.1-2003
Equivalent Metric ThreadM24 X 2

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

Table of Content


15/16 - 12 12-UN 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

15/16 - 12 12-UN 2A (External)

* Permisable values for thread Class 2A

# Description Value (Inch) Value (mm)
es Allowance 0.0016 (Ref) 0.041 (Ref)
d Major Diameter 0.924 - 0.9354 23.47 - 23.759
d2 Pitch Diameter 0.876 - 0.8813 22.25 - 22.385
d3 Minor Diameter
(UNR Only)
0.8362 (Ref) 21.239 (Ref)
α Varation of 30° anngle (+/-) 0.9167°
P Varation of pitch (+/-) 0.0015 (Ref) 0.038 (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


15/16 - 12 12-UN 3A (External)

* Permisable values for thread Class 3A

# Description Value (Inch) Value (mm)
es Allowance 0 (Ref) 0 (Ref)
d Major Diameter 0.9256 - 0.937 23.51 - 23.8
d2 Pitch Diameter 0.8789 - 0.8829 22.324 - 22.426
d3 Minor Diameter
(UNR Only)
0.8378 (Ref) 21.28 (Ref)
α Varation of 30° anngle (+/-) 0.9167°
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


15/16 - 12 12-UN 2B (Internal)

* Permisable values for thread Class 2B

# Description Value (Inch) Value (mm)
D1 Minor Diameter 0.847 - 0.865 21.514 - 21.971
D2 Pitch Diameter 0.8829 - 0.8898 22.426 - 22.601
D Major Diameter 0.9370 (Min) 23.8 (Min)
α Varation of 30° anngle (+/-) 0.9167°
P Varation of Pitch (+/-) 0.002 (Ref) 0.051 (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


15/16 - 12 12-UN 3B (Internal)

* Permisable values for thread Class 3B

# Description Value (Inch) Value (mm)
D1 Minor Diameter 0.8468 - 0.857 21.509 - 21.768
D2 Pitch Diameter 0.8829 - 0.8881 22.426 - 22.558
D Major Diameter 0.9370 (Min) 23.8 (Min)
α Varation of 30° anngle (+/-) 0.9167°
P Varation of Pitch (+/-) 0.0015 (Ref) 0.038 (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 15/16 - 12 12-UN

  • 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% 0.877 22.29
60% 0.872 22.15
65% 0.867 22.01
70% 0.861 21.87
75% 0.856 21.74
80% 0.850 21.60
85% 0.845 21.46

Over Wire Measurements for 15/16 - 12 12-UN


* 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 0.0421 - 0.0842 1.069 - 2.138
Ideal Wire Diameter 0.0481 1.222
Possible Wires
From Standard Sets
* 0.0642
* 0.0722
* 0.077
* 0.0825
* 1.155
* 1.443
* 1.732
* 2.021

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!


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