The following table defines recommended industry standard sizes for Internal ACME General Purpose Threads per American National Standard ASME/ANSI B1.5. All dimensional data is given in inches.
|
Designation
|
Size Decimal
|
TPI
|
Tol. Class
|
Minor Dia.
|
Pitch Dia.
|
Major Dia.
|
Tap Drill
|
|||
|
Min.
|
Max.
|
Min.
|
Max.
|
Min.
|
Max.
|
|||||
|
1/4-16 ACME
|
0.25
|
16
|
2G
|
0.1875
|
0.1925
|
0.2188
|
0.2293
|
0.2600
|
0.2700
|
0.1875
|
|
1/4-16 ACME
|
0.25
|
16
|
3G
|
0.1875
|
0.1925
|
0.2188
|
0.2237
|
0.2600
|
0.2700
|
0.1875
|
|
1/4-16 ACME
|
0.25
|
16
|
4G
|
0.1875
|
0.1925
|
0.2188
|
0.2223
|
0.2600
|
0.2700
|
0.1875
|
|
1/4-16 ACME
|
0.25
|
16
|
5G
|
0.1875
|
0.1925
|
0.2188
|
0.2216
|
0.2600
|
0.2700
|
0.1875
|
|
5/16-14 ACME
|
0.3125
|
14
|
2G
|
0.2411
|
0.2461
|
0.2768
|
0.2882
|
0.3225
|
0.3325
|
0.2411
|
|
5/16-14 ACME
|
0.3125
|
14
|
3G
|
0.2411
|
0.2461
|
0.2768
|
0.2821
|
0.3225
|
0.3325
|
0.2411
|
|
5/16-14 ACME
|
0.3125
|
14
|
4G
|
0.2411
|
0.2461
|
0.2768
|
0.2806
|
0.3225
|
0.3325
|
0.2411
|
|
5/16-14 ACME
|
0.3125
|
14
|
5G
|
0.2411
|
0.2461
|
0.2768
|
0.2798
|
0.3225
|
0.3325
|
0.2411
|
|
3/8-12 ACME
|
0.375
|
12
|
2G
|
0.2917
|
0.2967
|
0.3333
|
0.3456
|
0.3850
|
0.3950
|
0.2917
|
|
3/8-12 ACME
|
0.375
|
12
|
3G
|
0.2917
|
0.2967
|
0.3333
|
0.3391
|
0.3850
|
0.3950
|
0.2917
|
|
3/8-12 ACME
|
0.375
|
12
|
4G
|
0.2917
|
0.2967
|
0.3333
|
0.3374
|
0.3850
|
0.3950
|
0.2917
|
|
3/8-12 ACME
|
0.375
|
12
|
5G
|
0.2917
|
0.2967
|
0.3333
|
0.3366
|
0.3850
|
0.3950
|
0.2917
|
|
7/16-12 ACME
|
0.4375
|
12
|
2G
|
0.3542
|
0.3592
|
0.3958
|
0.4084
|
0.4475
|
0.4575
|
0.3542
|
|
7/16-12 ACME
|
0.4375
|
12
|
3G
|
0.3542
|
0.3592
|
0.3958
|
0.4017
|
0.4475
|
0.4575
|
0.3542
|
|
7/16-12 ACME
|
0.4375
|
12
|
4G
|
0.3542
|
0.3592
|
0.3958
|
0.4000
|
0.4475
|
0.4575
|
0.3542
|
|
7/16-12 ACME
|
0.4375
|
12
|
5G
|
0.3542
|
0.3592
|
0.3958
|
0.3992
|
0.4475
|
0.4575
|
0.3542
|
|
1/2-10 ACME
|
0.5
|
10
|
2G
|
0.4000
|
0.4050
|
0.4500
|
0.4637
|
0.52
|
0.5400
|
0.4000
|
|
1/2-10 ACME
|
0.5
|
10
|
3G
|
0.4000
|
0.4050
|
0.4500
|
0.4564
|
0.52
|
0.5400
|
0.4000
|
|
1/2-10 ACME
|
0.5
|
10
|
4G
|
0.4000
|
0.4050
|
0.4500
|
0.4546
|
0.52
|
0.5400
|
0.4000
|
|
1/2-10 ACME
|
0.5
|
10
|
5G
|
0.4000
|
0.4050
|
0.4500
|
0.4537
|
0.52
|
0.5400
|
0.4000
|
|
5/8-8 ACME
|
0.625
|
8
|
2G
|
0.5000
|
0.5062
|
0.5625
|
0.5779
|
0.645
|
0.6650
|
0.5000
|
|
5/8-8 ACME
|
0.625
|
8
|
3G
|
0.5000
|
0.5062
|
0.5625
|
0.5697
|
0.645
|
0.6650
|
0.5000
|
|
5/8-8 ACME
|
0.625
|
8
|
4G
|
0.5000
|
0.5062
|
0.5625
|
0.5676
|
0.645
|
0.6650
|
0.5000
|
|
5/8-8 ACME
|
0.625
|
8
|
5G
|
0.5000
|
0.5062
|
0.5625
|
0.5666
|
0.645
|
0.6650
|
0.5000
|
|
3/4-6 ACME
|
0.75
|
6
|
2G
|
0.5833
|
0.5916
|
0.6667
|
0.6841
|
0.77
|
0.7900
|
0.5833
|
|
3/4-6 ACME
|
0.75
|
6
|
3G
|
0.5833
|
0.5916
|
0.6667
|
0.6748
|
0.77
|
0.7900
|
0.5833
|
|
3/4-6 ACME
|
0.75
|
6
|
4G
|
0.5833
|
0.5916
|
0.6667
|
0.6725
|
0.77
|
0.7900
|
0.5833
|
|
3/4-6 ACME
|
0.75
|
6
|
5G
|
0.5833
|
0.5916
|
0.6667
|
0.6714
|
0.77
|
0.7900
|
0.5833
|
|
7/8-6 ACME
|
0.875
|
6
|
2G
|
0.7083
|
0.7166
|
0.7917
|
0.8096
|
0.895
|
0.9150
|
0.7083
|
|
7/8-6 ACME
|
0.875
|
6
|
3G
|
0.7083
|
0.7166
|
0.7917
|
0.8000
|
0.895
|
0.9150
|
0.7083
|
|
7/8-6 ACME
|
0.875
|
6
|
4G
|
0.7083
|
0.7166
|
0.7917
|
0.7977
|
0.895
|
0.9150
|
0.7083
|
|
7/8-6 ACME
|
0.875
|
6
|
5G
|
0.7083
|
0.7166
|
0.7917
|
0.7965
|
0.895
|
0.9150
|
0.7083
|
|
1-5 ACME
|
1
|
5
|
2G
|
0.8000
|
0.8100
|
0.9000
|
0.9194
|
1.02
|
1.0400
|
0.8000
|
|
1-5 ACME
|
1
|
5
|
3G
|
0.8000
|
0.8100
|
0.9000
|
0.9091
|
1.02
|
1.0400
|
0.8000
|
|
1-5 ACME
|
1
|
5
|
4G
|
0.8000
|
0.8100
|
0.9000
|
0.9065
|
1.02
|
1.0400
|
0.8000
|
|
1-5 ACME
|
1
|
5
|
5G
|
0.8000
|
0.8100
|
0.9000
|
0.9052
|
1.02
|
1.0400
|
0.8000
|
|
1 1/8-5 ACME
|
1.125
|
5
|
2G
|
0.9250
|
0.9350
|
1.0250
|
1.0448
|
1.145
|
1.165
|
0.9250
|
|
1 1/8-5 ACME
|
1.125
|
5
|
3G
|
0.9250
|
0.9350
|
1.0250
|
1.0342
|
1.145
|
1.165
|
0.9250
|
|
1 1/8-5 ACME
|
1.125
|
5
|
4G
|
0.9250
|
0.9350
|
1.0250
|
1.0316
|
1.145
|
1.165
|
0.9250
|
|
1 1/8-5 ACME
|
1.125
|
5
|
5G
|
0.9250
|
0.9350
|
1.0250
|
1.0303
|
1.145
|
1.165
|
0.9250
|
|
1 1/4-5 ACME
|
1.25
|
5
|
2G
|
1.0500
|
1.0600
|
1.1500
|
1.1701
|
1.27
|
1.29
|
1.0500
|
|
1 1/4-5 ACME
|
1.25
|
5
|
3G
|
1.0500
|
1.0600
|
1.1500
|
1.1594
|
1.27
|
1.29
|
1.0500
|
|
1 1/4-5 ACME
|
1.25
|
5
|
4G
|
1.0500
|
1.0600
|
1.1500
|
1.1567
|
1.27
|
1.29
|
1.0500
|
|
1 1/4-5 ACME
|
1.25
|
4
|
5G
|
1.0500
|
1.0600
|
1.1500
|
1.1554
|
1.27
|
1.29
|
1.0500
|
|
1 3/8-4 ACME
|
1.375
|
4
|
2G
|
1.1250
|
1.1375
|
1.2500
|
1.2720
|
1.395
|
1.415
|
1.1250
|
|
1 3/8-4 ACME
|
1.375
|
4
|
3G
|
1.1250
|
1.1375
|
1.2500
|
1.2603
|
1.395
|
1.415
|
1.1250
|
|
1 3/8-4 ACME
|
1.375
|
4
|
4G
|
1.1250
|
1.1375
|
1.2500
|
1.2573
|
1.395
|
1.415
|
1.1250
|
|
1 3/8-4 ACME
|
1.375
|
4
|
5G
|
1.1250
|
1.1375
|
1.2500
|
1.2559
|
1.395
|
1.415
|
1.1250
|
|
1 1/2-4 ACME
|
1.5
|
4
|
2G
|
1.2500
|
1.2625
|
1.3750
|
1.3973
|
1.52
|
1.54
|
1.2500
|
|
1 1/2-4 ACME
|
1.5
|
4
|
3G
|
1.2500
|
1.2625
|
1.3750
|
1.3854
|
1.52
|
1.54
|
1.2500
|
|
1 1/2-4 ACME
|
1.5
|
4
|
4G
|
1.2500
|
1.2625
|
1.3750
|
1.3824
|
1.52
|
1.54
|
1.2500
|
|
1 1/2-4 ACME
|
1.5
|
4
|
5G
|
1.2500
|
1.2625
|
1.3750
|
1.3810
|
1.52
|
1.54
|
1.2500
|
|
1 3/4-4 ACME
|
1.75
|
4
|
2G
|
1.5000
|
1.5125
|
1.6250
|
1.6479
|
1.77
|
1.79
|
1.5000
|
|
1 3/4-4 ACME
|
1.75
|
4
|
3G
|
1.5000
|
1.5125
|
1.6250
|
1.6357
|
1.77
|
1.79
|
1.5000
|
|
1 3/4-4 ACME
|
1.75
|
4
|
4G
|
1.5000
|
1.5125
|
1.6250
|
1.6326
|
1.77
|
1.79
|
1.5000
|
|
1 3/4-4 ACME
|
1.75
|
4
|
5G
|
1.5000
|
1.5125
|
1.6250
|
1.6311
|
1.77
|
1.79
|
1.5000
|
|
2-4 ACME
|
2
|
4
|
2G
|
1.7500
|
1.7625
|
1.8750
|
1.8985
|
2.02
|
2.04
|
1.7500
|
|
2-4 ACME
|
2
|
4
|
3G
|
1.7500
|
1.7625
|
1.8750
|
1.8860
|
2.02
|
2.04
|
1.7500
|
|
2-4 ACME
|
2
|
4
|
4G
|
1.7500
|
1.7625
|
1.8750
|
1.8828
|
2.02
|
2.04
|
1.7500
|
|
2-4 ACME
|
2
|
4
|
5G
|
1.7500
|
1.7625
|
1.8750
|
1.8813
|
2.02
|
2.04
|
1.7500
|
|
2 1/4-3 ACME
|
2.25
|
3
|
2G
|
1.9167
|
1.9334
|
2.0833
|
2.1096
|
2.27
|
2.29
|
1.9167
|
|
2 1/4-3 ACME
|
2.25
|
3
|
3G
|
1.9167
|
1.9334
|
2.0833
|
2.0956
|
2.27
|
2.29
|
1.9167
|
|
2 1/4-3 ACME
|
2.25
|
3
|
4G
|
1.9167
|
1.9334
|
2.0833
|
2.0921
|
2.27
|
2.29
|
1.9167
|
|
2 1/4-3 ACME
|
2.25
|
3
|
5G
|
1.9167
|
1.9334
|
2.0833
|
2.0903
|
2.27
|
2.29
|
1.9167
|
|
2 1/2-3 ACME
|
2.5
|
3
|
2G
|
2.1667
|
2.1834
|
2.3333
|
2.3601
|
2.52
|
2.54
|
2.1667
|
|
2 1/2-3 ACME
|
2.5
|
3
|
3G
|
2.1667
|
2.1834
|
2.3333
|
2.3458
|
2.52
|
2.54
|
2.1667
|
|
2 1/2-3 ACME
|
2.5
|
3
|
4G
|
2.1667
|
2.1834
|
2.3333
|
2.3422
|
2.52
|
2.54
|
2.1667
|
|
2 1/2-3 ACME
|
2.5
|
3
|
5G
|
2.1667
|
2.1834
|
2.3333
|
2.3404
|
2.52
|
2.54
|
2.1667
|
|
2 3/4-3 ACME
|
2.75
|
3
|
2G
|
2.4169
|
2.4334
|
2.5833
|
2.6106
|
2.77
|
2.79
|
2.4169
|
|
2 3/4-3 ACME
|
2.75
|
3
|
3G
|
2.4169
|
2.4334
|
2.5833
|
2.5960
|
2.77
|
2.79
|
2.4169
|
|
2 3/4-3 ACME
|
2.75
|
3
|
4G
|
2.4169
|
2.4334
|
2.5833
|
2.5924
|
2.77
|
2.79
|
2.4169
|
|
2 3/4-3 ACME
|
2.75
|
3
|
5G
|
2.4169
|
2.4334
|
2.5833
|
2.5906
|
2.77
|
2.79
|
2.4169
|
|
3-2 ACME
|
3
|
2
|
2G
|
2.5000
|
2.5250
|
2.7500
|
2.7816
|
3.02
|
3.04
|
2.5000
|
|
3-2 ACME
|
3
|
2
|
3G
|
2.5000
|
2.5250
|
2.7500
|
2.7647
|
3.02
|
3.04
|
2.5000
|
|
3-2 ACME
|
3
|
2
|
4G
|
2.5000
|
2.5250
|
2.7500
|
2.7605
|
3.02
|
3.04
|
2.5000
|
|
3-2 ACME
|
3
|
2
|
5G
|
2.5000
|
2.5250
|
2.7500
|
2.7584
|
3.02
|
3.04
|
2.5000
|
|
3 1/2-2 ACME
|
3.5
|
2
|
2G
|
3.0000
|
3.0250
|
3.2500
|
3.2824
|
3.52
|
3.54
|
3.0000
|
|
3 1/2-2 ACME
|
3.5
|
2
|
3G
|
3.0000
|
3.0250
|
3.2500
|
3.2651
|
3.52
|
3.54
|
3.0000
|
|
3 1/2-2 ACME
|
3.5
|
2
|
4G
|
3.0000
|
3.0250
|
3.2500
|
3.2608
|
3.52
|
3.54
|
3.0000
|
|
3 1/2-2 ACME
|
3.5
|
2
|
5G
|
3.0000
|
3.0250
|
3.2500
|
3.2587
|
3.52
|
3.54
|
3.0000
|
|
4-2 ACME
|
4
|
2
|
2G
|
3.5000
|
3.5250
|
3.7500
|
3.7832
|
4.02
|
4.04
|
3.5000
|
|
4-2 ACME
|
4
|
2
|
3G
|
3.5000
|
3.5250
|
3.7500
|
3.7655
|
4.02
|
4.04
|
3.5000
|
|
4-2 ACME
|
4
|
2
|
4G
|
3.5000
|
3.5250
|
3.7500
|
3.7611
|
4.02
|
4.04
|
3.5000
|
|
4-2 ACME
|
4
|
2
|
5G
|
3.5000
|
3.5250
|
3.7500
|
3.7589
|
4.02
|
4.04
|
3.5000
|
|
4 1/2-2 ACME
|
4.5
|
2
|
2G
|
4.0000
|
4.0250
|
4.2500
|
4.2839
|
4.52
|
4.54
|
4.0000
|
|
4 1/2-2 ACME
|
4.5
|
2
|
3G
|
4.0000
|
4.0250
|
4.2500
|
4.2658
|
4.52
|
4.54
|
4.0000
|
|
4 1/2-2 ACME
|
4.5
|
2
|
4G
|
4.0000
|
4.0250
|
4.2500
|
4.2613
|
4.52
|
4.54
|
4.0000
|
|
4 1/2-2 ACME
|
4.5
|
2
|
5G
|
4.0000
|
4.0250
|
4.2500
|
4.2591
|
4.52
|
4.54
|
4.0000
|
|
5-2 ACME
|
5
|
2
|
2G
|
4.5000
|
4.5250
|
4.7500
|
4.7846
|
5.02
|
5.04
|
4.5000
|
|
5-2 ACME
|
5
|
2
|
3G
|
4.5000
|
4.5250
|
4.7500
|
4.7662
|
5.02
|
5.04
|
4.5000
|
|
5-2 ACME
|
5
|
2
|
4G
|
4.5000
|
4.5250
|
4.7500
|
4.7615
|
5.02
|
5.04
|
4.5000
|
|
5-2 ACME
|
5
|
2
|
5G
|
4.5000
|
4.5250
|
4.7500
|
4.7592
|
5.02
|
5.04
|
4.5000
|
