AmesWeb
UNF THREAD CHART
UNF thread chart
according to ASME B1.1 standard.
UNF Thread Chart — External Thread Dimensions
Nominal
Diameter
TPI
Tolerance
Class
Major Dia.
Pitch Dia.
Max.
Minor
Diameter
max.
min.
max.
min.
#0 - 80
80
2A
0.0595
0.0563
0.0514
0.0496
0.0446
#1 - 72
72
2A
0.0724
0.0689
0.0634
0.0615
0.0559
#2 - 64
64
2A
0.0854
0.0816
0.0753
0.0733
0.0668
#3 - 56
56
2A
0.0983
0.0942
0.0867
0.0845
0.0771
#4 - 48
48
2A
0.1113
0.1068
0.0979
0.0954
0.0864
#5 - 44
44
2A
0.1243
0.1195
0.1095
0.1070
0.0972
#6 - 40
40
2A
0.1372
0.1321
0.1210
0.1184
0.1074
#8 - 36
36
2A
0.1632
0.1577
0.1452
0.1424
0.1301
#10 - 32
32
2A
0.1891
0.1831
0.1688
0.1658
0.1519
#12 - 28
28
2A
0.2150
0.2085
0.1918
0.1886
0.1724
1/4" - 28
28
2A
0.2490
0.2425
0.2258
0.2225
0.2064
5/16" - 24
24
2A
0.3114
0.3042
0.2843
0.2806
0.2618
3/8" - 24
24
2A
0.3739
0.3667
0.3468
0.3430
0.3243
7/16" - 20
20
2A
0.4362
0.4281
0.4037
0.3995
0.3767
Nominal
Diameter
TPI
Tolerance
Class
Major Dia.
Pitch Dia.
Max.
Minor
Diameter
max.
min.
max.
min.
1/2" - 20
20
2A
0.4987
0.4906
0.4662
0.4619
0.4392
9/16" - 18
18
2A
0.5611
0.5524
0.5250
0.5205
0.4950
5/8" - 18
18
2A
0.6236
0.6149
0.5875
05828
0.5575
3/4" - 16
16
2A
0.7485
0.7391
0.7079
0.7029
0.6740
7/8" - 14
14
2A
0.8734
0.8631
0.8270
0.8216
0.7884
1" - 12
12
2A
0.9982
0.9868
0.9441
0.9382
0.8990
1 1/8" - 12
12
2A
1.1232
1.1118
1.0691
1.0631
1.0240
1 1/4" - 12
12
2A
1.2482
1.2368
1.1941
1.1879
1.4190
1 3/8" - 12
12
2A
1.3731
1.3617
1.3190
1.3127
1.2739
1 1/2" - 12
12
2A
1.4981
1.4867
1.4440
1.4376
1.3989
Nominal
Diameter
TPI
Tolerance
Class
max.
min.
max.
min.
Max.
Minor
Diameter
Major Dia.
Pitch Dia.
UNF Thread Chart — Internal Thread Dimensions
Nominal
Diameter
TPI
Tolerance
Class
Major Dia.
Pitch Dia.
Minor Dia.
min.
max.
min.
max.
min
#0 - 80
80
2B
0.0600
0.0542
0.0519
0.0514
0.0465
#1 - 72
72
2B
0.0730
0.0665
0.0640
0.0635
0.0580
#2 - 64
64
2B
0.0860
0.0786
0.0759
0.0753
0.0691
#3 - 56
56
2B
0.0990
0.0902
0.0874
0.0865
0.0797
#4 - 48
48
2B
0.1120
0.1016
0.0985
0.0968
0.0894
#5 - 44
44
2B
0.1250
0.1134
0.1102
0.1079
0.1004
#6 - 40
40
2B
0.1380
0.1252
0.1218
0.1190
0.1110
#8 - 36
36
2B
0.1640
0.1496
0.1460
0.1420
0.1340
#10 - 32
32
2B
0.1900
0.1736
0.1697
0.1640
0.1560
#12 - 28
28
2B
0.2160
0.1970
0.1928
0.1860
0.1770
1/4" - 28
28
2B
0.2500
0.2333
0.2268
0.2200
0.2110
5/16" - 24
24
2B
0.3125
0.2925
0.2854
0.2770
0.2670
3/8" - 24
24
2B
0.3750
0.3553
0.3479
0.3400
0.3300
7/16" - 20
20
2B
0.4375
0.4131
0.4050
0.3950
0.3830
Nominal
Diameter
TPI
Tolerance
Class
Major Dia.
Pitch Dia.
Minor Dia.
min.
max.
min.
max.
min.
1/2" - 20
20
2B
0.5000
0.4731
0.4675
0.4570
0.4460
9/16" - 18
18
2B
0.5625
0.5323
0.5264
0.5150
0.5020
5/8" - 18
18
2B
0.5625
0.5949
0.5889
0.5780
0.5650
3/4" - 16
16
2B
0.7500
0.7159
0.7094
0.6960
0.6820
7/8" - 14
14
2B
0.8750
0.8356
0.8266
0.8140
0.7980
1" - 12
12
2B
1.0000
0.9535
0.9459
0.9280
0.9100
1 1/8" - 12
12
2B
1.1250
1.0787
1.0709
1.0530
1.0350
1 1/4" - 12
12
2B
1.2500
1.2039
1.1959
1.1780
1.1600
1 3/8" - 12
12
2B
1.3750
1.3291
1.3209
1.3030
1.2850
1 1/2" - 12
12
2B
1.5000
1.4542
1.4459
1.4280
1.4100
Nominal
Diameter
TPI
Tolerance
Class
min.
max.
min.
max.
min.
Major Dia.
Pitch Dia.
Minor Dia.
General Note: All dimensions expressed in inches.
Supplements:
Thread calculators and charts
ASME UN screw thread calculator
Reference:
ASME B1.1-2003, Unified Inch Screw Threads (UN and UNR Thread Form)
Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) .
Machinery's Handbook
. 30th edition. Industrial Press Inc.
Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2012) .
Machinery's Handbook
. 29th edition. Industrial Press Inc.