UNIFIED INCH SCREW THREADS (UN UNC UNF UNEF)

Unified Inch Screw Thread Profile

UN Profile

Unified Inch Screw Thread Tolerance

UN Tolerance

Classes 1A, 2A, and 3A apply to external threads only, and Classes 1B, 2B, and 3B apply to internal threads only. Allowance is specified only for Classes 1A and 2A and the allowance is identical for both classes. Tolerance decreases as class number increases (e.g., tolerance for Class 3A is less than that for Class 2A, which is less than that for Class 1A).

(a) Example of UN external thread : 1/4-20 UNC 2A

  • 1/4 : Nominal size
  • 20 : Threads per inch (TPI)
  • UNC : Thread series : Coarse
  • 2A : Tolerance class

(b) Example of UN internal thread : 4-48 UNF 2B

  • 4 : Nominal size
  • 48 : Threads per inch (TPI)
  • UNF : Thread series : Fine
  • 2B : Tolerance class

Thread series are groups of diameter-pitch combinations distinguished from each other by the number of threads per inch applied to a series of specific diameters. There are two general series classifications: standard and special.

  • Standard Series. The standard series consists of three series with graded pitches (coarse UNC, fine UNF, and extra fine UNEF) and eight series with constant pitches (4, 6, 8, 12, 16, 20, 28, and 32 threads per inch).
  • Special Series UNS. The special series consists of all threads with diameter-pitch combinations that are not included in the standard series.

Unified Inch Screw Thread Dimension

invalid size
invalid TPI

Pitch diameter tolerance

Major diameter tolerance

Lengths of Engagement (default LE = 9 pitches)

invalid LE

Result unit

Decimal places

Data not found

Pitch :

P =

0

mm

Height of fundamental triangle :

H =

0

mm

Height of thread :

h =

0

mm

Major diameter (mm)

0.000

0.000

0.000

=

invalid size

Minor diameter (mm)

0.000

0.000

0.000

=

invalid size

Pitch diameter (mm)

0.000

0.000

0.000

=

invalid size

For not specified tolerance, we use the pitch tolerance to calculate the average value.

Unified Inch Screw Thread Standard Series

Size-TPIEquivalentSeriesEx.classIn.class
0-800.060-80UNF2A , 3A2B , 3B
1-640.073-64UNC2A , 3A2B , 3B
1-720.073-72UNF2A , 3A2B , 3B
2-560.086-56UNC2A , 3A2B , 3B
2-640.086-64UNF2A , 3A2B , 3B
3-480.099-48UNC2A , 3A2B , 3B
3-560.099-56UNF2A , 3A2B , 3B
4-400.112-40UNC2A , 3A2B , 3B
4-480.112-48UNF2A , 3A2B , 3B
5-400.125-40UNC2A , 3A2B , 3B
5-440.125-44UNF2A , 3A2B , 3B
6-320.138-32UNC2A , 3A2B , 3B
6-400.138-40UNF2A , 3A2B , 3B
8-320.164-32UNC2A , 3A2B , 3B
8-360.164-36UNF2A , 3A2B , 3B
10-240.190-24UNC2A , 3A2B , 3B
10-320.190-32UNF2A , 3A2B , 3B
12-240.216-24UNC2A , 3A2B , 3B
12-280.216-28UNF2A , 3A2B , 3B
12-320.216-32UNEF2A , 3A2B , 3B
1/4-200.2500-20UNC1A , 2A , 3A1B , 2B , 3B
1/4-280.2500-28UNF1A , 2A , 3A1B , 2B , 3B
1/4-320.2500-32UNEF2A , 3A2B , 3B
5/16-180.3125-18UNC1A , 2A , 3A1B , 2B , 3B
5/16-200.3125-20UNEF2A , 3A2B , 3B
5/16-240.3125-24UNF1A , 2A , 3A1B , 2B , 3B
5/16-280.3125-28UN2A , 3A2B , 3B
5/16-320.3125-32UNEF2A , 3A2B , 3B
3/8-160.3750-16UNC1A , 2A , 3A1B , 2B , 3B
3/8-200.3750-20UN 2A , 3A2B , 3B
3/8-240.3750-24UNF1A , 2A , 3A1B , 2B , 3B
3/8-280.3750-28UN2A , 3A2B , 3B
3/8-320.3750-32UNEF2A , 3A2B , 3B
7/16-140.4375-14UNC1A , 2A , 3A1B , 2B , 3B
7/16-160.4375-16UN2A , 3A2B , 3B
7/16-200.4375-20UNF1A , 2A , 3A1B , 2B , 3B
7/16-280.4375-28UNEF2A , 3A2B , 3B
7/16-320.4375-32UNEF2A , 3A2B , 3B
1/2-130.5000-13UNC1A , 2A , 3A1B , 2B , 3B
1/2-160.5000-16UN2A , 3A2B , 3B
1/2-200.5000-20UNF1A , 2A , 3A1B , 2B , 3B
1/2-280.5000-28UNEF2A , 3A2B , 3B
1/2-320.5000-32UN2A , 3A2B , 3B
9/16-120.5625-12UNC1A , 2A , 3A1B , 2B , 3B
9/16-160.5625-16UN2A , 3A2B , 3B
9/16-180.5625-18UNF1A , 2A , 3A1B , 2B , 3B
9/16-200.5625-20UN2A , 3A2B , 3B
9/16-240.5625-24UNEF2A , 3A2B , 3B
9/16-280.5625-28UN2A , 3A2B , 3B
9/16-320.5625-32UN2A , 3A2B , 3B
5/8-110.6250-11UNC1A , 2A , 3A1B , 2B , 3B
5/8-120.6250-12UN2A , 3A2B , 3B
5/8-160.6250-16UN2A , 3A2B , 3B
5/8-180.6250-18UNF1A , 2A , 3A1B , 2B , 3B
5/8-200.6250-20UN2A , 3A2B , 3B
5/8-240.6250-24UNEF2A , 3A2B , 3B
5/8-280.6250-28UN2A , 3A2B , 3B
5/8-320.6250-32UN2A , 3A2B , 3B
11/16-120.6875-12UN2A , 3A2B , 3B
11/16-160.6875-16UN2A , 3A2B , 3B
11/16-200.6875-20UN2A , 3A2B , 3B
11/16-240.6875-24UNEF2A , 3A2B , 3B
11/16-280.6875-28UN2A , 3A2B , 3B
11/16-320.6875-32UN2A , 3A2B , 3B
3/4-100.7500-10UNC1A , 2A , 3A1B , 2B , 3B
3/4-120.7500-12UN2A , 3A2B , 3B
3/4-160.7500-16UNF1A , 2A , 3A1B , 2B , 3B
3/4-200.7500-20UNEF2A , 3A2B , 3B
3/4-280.7500-28UN2A , 3A2B , 3B
3/4-320.7500-32UN2A , 3A2B , 3B
13/16-120.8125-12UN2A , 3A2B , 3B
13/16-160.8125-16UN2A , 3A2B , 3B
13/16-200.8125-20UNEF2A , 3A2B , 3B
13/16-280.8125-28UN2A , 3A2B , 3B
13/16-320.8125-32UN2A , 3A2B , 3B
7/8-90.8750-9UNC1A , 2A , 3A1B , 2B , 3B
7/8-120.8750-12UN2A , 3A2B , 3B
7/8-140.8750-14UNF1A , 2A , 3A1B , 2B , 3B
7/8-160.8750-16UN2A , 3A2B , 3B
7/8-200.8750-20UNEF2A , 3A2B , 3B
7/8-280.8750-28UN2A , 3A2B , 3B
7/8-320.8750-32UN2A , 3A2B , 3B
15/16-120.9375-12UN2A , 3A2B , 3B
15/16-160.9375-16UN2A , 3A2B , 3B
15/16-200.9375-20UNEF2A , 3A2B , 3B
15/16-280.9375-28UN2A , 3A2B , 3B
15/16-320.9375-32UN2A , 3A2B , 3B
1-81.0000-8UNC1A , 2A , 3A1B , 2B , 3B
1-121.0000-12UNF1A , 2A , 3A1B , 2B , 3B
1-141.0000-14UNS2A , 3A2B , 3B
1-161.0000-16UN2A , 3A2B , 3B
1-201.0000-20UNEF2A , 3A2B , 3B
1-281.0000-28UN2A , 3A2B , 3B
1-321.0000-32UN2A , 3A2B , 3B
1 1/16-81.0625-8UN2A , 3A2B , 3B
1 1/16-121.0625-12UN2A , 3A2B , 3B
1 1/16-161.0625-16UN2A , 3A2B , 3B
1 1/16-181.0625-18UNEF2A , 3A2B , 3B
1 1/16-201.0625-20UN2A , 3A2B , 3B
1 1/16-281.0625-28UN2A , 3A2B , 3B
1 1/8-71.1250-7UNC1A , 2A , 3A1B , 2B , 3B
1 1/8-81.1250-8UN2A , 3A2B , 3B
1 1/8-121.1250-12UNF1A , 2A , 3A1B , 2B , 3B
1 1/8-161.1250-16UN2A , 3A2B , 3B
1 1/8-181.1250-18UNEF2A , 3A2B , 3B
1 1/8-201.1250-20UN2A , 3A2B , 3B
1 1/8-281.1250-28UN2A , 3A2B , 3B
1 3/16-81.1875-8UN2A , 3A2B , 3B
1 3/16-121.1875-12UN2A , 3A2B , 3B
1 3/16-161.1875-16UN2A , 3A2B , 3B
1 3/16-181.1875-18UNEF2A , 3A2B , 3B
1 3/16-201.1875-20UN2A , 3A2B , 3B
1 3/16-281.1875-28UN2A , 3A2B , 3B
1 1/4-71.2500-7UNC1A , 2A , 3A1B , 2B , 3B
1 1/4-81.2500-8UN2A , 3A2B , 3B
1 1/4-121.2500-12UNF2A , 3A2B , 3B
1 1/4-161.2500-16UN2A , 3A2B , 3B
1 1/4-181.2500-18UNEF2A , 3A2B , 3B
1 1/4-201.2500-20UN2A , 3A2B , 3B
1 1/4-281.2500-28UN2A , 3A2B , 3B
1 5/16-81.3125-8UN2A , 3A2B , 3B
1 5/16-121.3125-12UN2A , 3A2B , 3B
1 5/16-161.3125-16UN2A , 3A2B , 3B
1 5/16-181.3125-18UNEF2A , 3A2B , 3B
1 5/16-201.3125-20UN2A , 3A2B , 3B
1 5/16-281.3125-28UN2A , 3A2B , 3B
1 3/8-61.3750-6UNC1A , 2A , 3A1B , 2B , 3B
1 3/8-81.3750-8UN2A , 3A2B , 3B
1 3/8-121.3750-12UNF1A , 2A , 3A1B , 2B , 3B
1 3/8-161.3750-16UN2A , 3A2B , 3B
1 3/8-181.3750-18UNEF2A , 3A2B , 3B
1 3/8-201.3750-20UN2A , 3A2B , 3B
1 3/8-281.3750-28UN2A , 3A2B , 3B
1 7/16-61.4375-6UN2A , 3A2B , 3B
1 7/16-81.4375-8UN2A , 3A2B , 3B
1 7/16-121.4375-12UN2A , 3A2B , 3B
1 7/16-161.4375-16UN2A , 3A2B , 3B
1 7/16-181.4375-18UNEF2A , 3A2B , 3B
1 7/16-201.4375-20UN2A , 3A2B , 3B
1 7/16-281.4375-28UN2A , 3A2B , 3B
1 1/2-61.5000-6UNC1A , 2A , 3A1B , 2B , 3B
1 1/2-81.5000-8UN2A , 3A2B , 3B
1 1/2-121.5000-12UNF1A , 2A , 3A1B , 2B , 3B
1 1/2-161.5000-16UN2A , 3A2B , 3B
1 1/2-181.5000-18UNEF2A , 3A2B , 3B
1 1/2-201.5000-20UN2A , 3A2B , 3B
1 1/2-281.5000-28UN2A , 3A2B , 3B
1 9/16-61.5625-6UN2A , 3A2B , 3B
1 9/16-81.5625-8UN2A , 3A2B , 3B
1 9/16-121.5625-12UN2A , 3A2B , 3B
1 9/16-161.5625-16UN2A , 3A2B , 3B
1 9/16-181.5625-18UNEF2A , 3A2B , 3B
1 9/16-201.5625-20UN2A , 3A2B , 3B
1 5/8-61.6250-6UN2A , 3A2B , 3B
1 5/8-81.6250-8UN2A , 3A2B , 3B
1 5/8-121.6250-12UN2A , 3A2B , 3B
1 5/8-161.6250-16UN2A , 3A2B , 3B
1 5/8-181.6250-18UNEF2A , 3A2B , 3B
1 5/8-201.6250-20UN2A , 3A2B , 3B
1 11/16-61.6875-6UN2A , 3A2B , 3B
1 11/16-81.6875-8UN2A , 3A2B , 3B
1 11/16-121.6875-12UN2A , 3A2B , 3B
1 11/16-161.6875-16UN2A , 3A2B , 3B
1 11/16-181.6875-18UNEF2A , 3A2B , 3B
1 11/16-201.6875-20UN2A , 3A2B , 3B
1 3/4-51.7500-5UN1A , 2A , 3A1B , 2B , 3B
1 3/4-61.7500-6UN2A , 3A2B , 3B
1 3/4-81.7500-8UN2A , 3A2B , 3B
1 3/4-121.7500-12UN2A , 3A2B , 3B
1 3/4-161.7500-16UN2A , 3A2B , 3B
1 3/4-201.7500-20UN2A , 3A2B , 3B
1 13/16-61.8125-6UN2A , 3A2B , 3B
1 13/16-81.8125-8UN2A , 3A2B , 3B
1 13/16-121.8125-12UN2A , 3A2B , 3B
1 13/16-161.8125-16UN2A , 3A2B , 3B
1 13/16-201.8125-20UN2A , 3A2B , 3B
1 7/8-61.8750-6UN2A , 3A2B , 3B
1 7/8-81.8750-8UN2A , 3A2B , 3B
1 7/8-121.8750-12UN2A , 3A2B , 3B
1 7/8-161.8750-16UN2A , 3A2B , 3B
1 7/8-201.8750-20UN2A , 3A2B , 3B
1 15/16-61.9375-6UN2A , 3A2B , 3B
1 15/16-81.9375-8UN2A , 3A2B , 3B
1 15/16-121.9375-12UN2A , 3A2B , 3B
1 15/16-161.9375-16UN2A , 3A2B , 3B
1 15/16-201.9375-20UN2A , 3A2B , 3B
2-4.52.0000-4.5UNC1A , 2A , 3A1B , 2B , 3B
2-62.0000-6UN2A , 3A2B , 3B
2-82.0000-8UN2A , 3A2B , 3B
2-122.0000-12UN2A , 3A2B , 3B
2-162.0000-16UN2A , 3A2B , 3B
2-202.0000-20UN2A , 3A2B , 3B
2 1/8-62.1250-6UN2A , 3A2B , 3B
2 1/8-82.1250-8UN2A , 3A2B , 3B
2 1/8-122.1250-12UN2A , 3A2B , 3B
2 1/8-162.1250-16UN2A , 3A2B , 3B
2 1/8-202.1250-20UN2A , 3A2B , 3B
2 1/4-4.52.2500-4.5UNC1A , 2A , 3A1B , 2B , 3B
2 1/4-62.2500-6UN2A , 3A2B , 3B
2 1/4-82.2500-8UN2A , 3A2B , 3B
2 1/4-122.2500-12UN2A , 3A2B , 3B
2 1/4-162.2500-16UN2A , 3A2B , 3B
2 1/4-202.2500-20UN2A , 3A2B , 3B
2 3/8-62.3750-6UN2A , 3A2B , 3B
2 3/8-82.3750-8UN2A , 3A2B , 3B
2 3/8-122.3750-12UN2A , 3A2B , 3B
2 3/8-162.3750-16UN2A , 3A2B , 3B
2 3/8-202.3750-20UN2A , 3A2B , 3B
2 1/2-42.5000-4UNC1A , 2A , 3A1B , 2B , 3B
2 1/2-62.5000-6UNC2A , 3A2B , 3B
2 1/2-82.5000-8UN2A , 3A2B , 3B
2 1/2-122.5000-12UN2A , 3A2B , 3B
2 1/2-162.5000-16UN2A , 3A2B , 3B
2 1/2-202.5000-20UN2A , 3A2B , 3B
2 5/8-82.6250-8UN2A , 3A2B , 3B
2 5/8-122.6250-12UN2A , 3A2B , 3B
2 5/8-162.6250-16UN2A , 3A2B , 3B
2 5/8-202.6250-20UN2A , 3A2B , 3B
2 3/4-42.7500-4UNC1A , 2A , 3A1B , 2B , 3B
2 3/4-62.7500-6UN2A , 3A2B , 3B
2 3/4-82.7500-8UN2A , 3A2B , 3B
2 3/4-122.7500-12UN2A , 3A2B , 3B
2 3/4-162.7500-16UN2A , 3A2B , 3B
2 3/4-202.7500-20UN2A , 3A2B , 3B
2 7/8-62.8750-6UN2A , 3A2B , 3B
2 7/8-82.8750-8UN2A , 3A2B , 3B
2 7/8-122.8750-12UN2A , 3A2B , 3B
2 7/8-162.8750-16UN2A , 3A2B , 3B
2 7/8-202.8750-20UN2A , 3A2B , 3B
3-43.0000-4UNC1A , 2A , 3A1B , 2B , 3B
3-63.0000-6UN2A , 3A2B , 3B
3-83.0000-8UN2A , 3A2B , 3B
3-123.0000-12UN2A , 3A2B , 3B
3-163.0000-16UN2A , 3A2B , 3B
3-203.0000-20UN2A , 3A2B , 3B
3 1/8-63.1250-6UN2A , 3A2B , 3B
3 1/8-83.1250-8UN2A , 3A2B , 3B
3 1/8-123.1250-12UN2A , 3A2B , 3B
3 1/8-163.1250-16UN2A , 3A2B , 3B
3 1/4-43.2500-4UNC1A , 2A , 3A1B , 2B , 3B
3 1/4-63.2500-6UN2A , 3A2B , 3B
3 1/4-83.2500-8UN2A , 3A2B , 3B
3 1/4-123.2500-12UN2A , 3A2B , 3B
3 1/4-163.2500-16UN2A , 3A2B , 3B
3 3/8-63.3750-6UN2A , 3A2B , 3B
3 3/8-83.3750-8UN2A , 3A2B , 3B
3 3/8-123.3750-12UN2A , 3A2B , 3B
3 3/8-163.3750-16UN2A , 3A2B , 3B
3 1/2-43.5000-4UNC1A , 2A , 3A1B , 2B , 3B
3 1/2-63.5000-6UN2A , 3A2B , 3B
3 1/2-83.5000-8UN2A , 3A2B , 3B
3 1/2-123.5000-12UN2A , 3A2B , 3B
3 1/2-163.5000-16UN2A , 3A2B , 3B
3 5/8-63.6250-6UN2A , 3A2B , 3B
3 5/8-83.6250-8UN2A , 3A2B , 3B
3 5/8-123.6250-12UN2A , 3A2B , 3B
3 5/8-163.6250-16UN2A , 3A2B , 3B
3 3/4-43.7500-4UNC1A , 2A , 3A1B , 2B , 3B
3 3/4-63.7500-6UN2A , 3A2B , 3B
3 3/4-83.7500-8UN2A , 3A2B , 3B
3 3/4-123.7500-12UN2A , 3A2B , 3B
3 3/4-163.7500-16UN2A , 3A2B , 3B
3 7/8-63.8750-6UN2A , 3A2B , 3B
3 7/8-83.8750-8UN2A , 3A2B , 3B
3 7/8-123.8750-12UN2A , 3A2B , 3B
3 7/8-163.8750-16UN2A , 3A2B , 3B
4-44.0000-4UNC1A , 2A , 3A1B , 2B , 3B
4-64.0000-6UN2A , 3A2B , 3B
4-84.0000-8UN2A , 3A2B , 3B
4-124.0000-12UN2A , 3A2B , 3B
4-164.0000-16UN2A , 3A2B , 3B
4 1/8-64.1250-6UN2A , 3A2B , 3B
4 1/8-84.1250-8UN2A , 3A2B , 3B
4 1/8-124.1250-12UN2A , 3A2B , 3B
4 1/8-164.1250-16UN2A , 3A2B , 3B
4 1/4-44.2500-4UN2A , 3A2B , 3B
4 1/4-64.2500-6UN2A , 3A2B , 3B
4 1/4-84.2500-8UN2A , 3A2B , 3B
4 1/4-124.2500-12UN2A , 3A2B , 3B
4 1/4-164.2500-16UN2A , 3A2B , 3B
4 3/8-64.3750-6UN2A , 3A2B , 3B
4 3/8-84.3750-8UN2A , 3A2B , 3B
4 3/8-124.3750-12UN2A , 3A2B , 3B
4 3/8-164.3750-16UN2A , 3A2B , 3B
4 1/2-44.5000-4UN2A , 3A2B , 3B
4 1/2-64.5000-6UN2A , 3A2B , 3B
4 1/2-84.5000-8UN2A , 3A2B , 3B
4 1/2-124.5000-12UN2A , 3A2B , 3B
4 1/2-164.5000-16UN2A , 3A2B , 3B
4 5/8-64.6250-6UN2A , 3A2B , 3B
4 5/8-84.6250-8UN2A , 3A2B , 3B
4 5/8-124.6250-12UN2A , 3A2B , 3B
4 5/8-164.6250-16UN2A , 3A2B , 3B
4 3/4-44.7500-4UN2A , 3A2B , 3B
4 3/4-64.7500-6UN2A , 3A2B , 3B
4 3/4-84.7500-8UN2A , 3A2B , 3B
4 3/4-124.7500-12UN2A , 3A2B , 3B
4 3/4-164.7500-16UN2A , 3A2B , 3B
4 7/8-64.8750-6UN2A , 3A2B , 3B
4 7/8-84.8750-8UN2A , 3A2B , 3B
4 7/8-124.8750-12UN2A , 3A2B , 3B
4 7/8-164.8750-16UN2A , 3A2B , 3B
5-45.0000-4UN2A , 3A2B , 3B
5-65.0000-6UN2A , 3A2B , 3B
5-85.0000-8UN2A , 3A2B , 3B
5-125.0000-12UN2A , 3A2B , 3B
5-165.0000-16UN2A , 3A2B , 3B
5 1/8-65.1250-6UN2A , 3A2B , 3B
5 1/8-85.1250-8UN2A , 3A2B , 3B
5 1/8-125.1250-12UN2A , 3A2B , 3B
5 1/8-165.1250-16UN2A , 3A2B , 3B
5 1/4-45.2500-4UN2A , 3A2B , 3B
5 1/4-65.2500-6UN2A , 3A2B , 3B
5 1/4-85.2500-8UN2A , 3A2B , 3B
5 1/4-125.2500-12UN2A , 3A2B , 3B
5 1/4-165.2500-16UN2A , 3A2B , 3B
5 3/8-65.3750-6UN2A , 3A2B , 3B
5 3/8-85.3750-8UN2A , 3A2B , 3B
5 3/8-125.3750-12UN2A , 3A2B , 3B
5 3/8-165.3750-16UN2A , 3A2B , 3B
5 1/2-45.5000-4UN2A , 3A2B , 3B
5 1/2-65.5000-6UN2A , 3A2B , 3B
5 1/2-85.5000-8UN2A , 3A2B , 3B
5 1/2-125.5000-12UN2A , 3A2B , 3B
5 1/2-165.5000-16UN2A , 3A2B , 3B
5 5/8-65.6250-6UN2A , 3A2B , 3B
5 5/8-85.6250-8UN2A , 3A2B , 3B
5 5/8-125.6250-12UN2A , 3A2B , 3B
5 5/8-165.6250-16UN2A , 3A2B , 3B
5 3/4-45.7500-4UN2A , 3A2B , 3B
5 3/4-65.7500-6UN2A , 3A2B , 3B
5 3/4-85.7500-8UN2A , 3A2B , 3B
5 3/4-125.7500-12UN2A , 3A2B , 3B
5 3/4-165.7500-16UN2A , 3A2B , 3B
5 7/8-65.8750-6UN2A , 3A2B , 3B
5 7/8-85.8750-8UN2A , 3A2B , 3B
5 7/8-125.8750-12UN2A , 3A2B , 3B
5 7/8-165.8750-16UN2A , 3A2B , 3B
6-46.0000-4UN2A , 3A2B , 3B
6-66.0000-6UN2A , 3A2B , 3B
6-86.0000-8UN2A , 3A2B , 3B
6-126.0000-12UN2A , 3A2B , 3B
6-166.0000-16UN2A , 3A2B , 3B