ANSI Taps Fraction-Size Tolerances Per ASME B94.9

Manufacturing Reference Data | Mechanical Tolerances

ANSI Taps Fraction-Size Per ASME B94.9

  • ‚ÄčAll dimensions are given in inches.
  • Lead Tolerance: Plus or minus 0.003 inch max. per inch of thread.
  • Angle Tolerance: Plus or minus 35 min. in half angle or 53 min. in full angle for 4 1⁄2 to 5 1⁄2 thds. per in.; 40 min. half angle and 60 min. full angle for 6 to 9 thds.; 45 min. half angle and 68 min. full angle for 10 to 28 thds.; 60 min. half angle and 90 min. full angle for 30 to 64 thds. per in.

ANSI Standard Fraction-Size Taps — Cut Thread Limits Per ASME B94.9

Tap Size
Threads per Inch
Major Diameter
Pitch Diameter
 
 
NC UNC
NF UNF
NS UNS
Basic
Min.
Max.
Basic
Min.
Max.
1/8
40
0.1250
0.1266
0.1286
0.1088
0.1090
0.1105
5⁄32
32
0.1563
0.1585
0.1605
0.1360
0.1365
0.1380
3⁄16
24
0.1875
0.1903
0.1923
0.1604
0.1609
0.1624
3⁄16
32
0.1875
0.1897
0.1917
0.1672
0.1677
0.1692
1⁄4
20
0.2500
0.2532
0.2557
0.2175
0.2180
0.2200
1⁄4
28
0.2500
0.2524
0.2549
0.2268
0.2273
0.2288
5⁄16
18
0.3125
0.3160
0.3185
0.2764
0.2769
0.2789
5⁄16
24
0.3125
0.3153
0.3178
0.2854
0.2859
0.2874
3⁄8
16
0.3750
0.3789
0.3814
0.3344
0.3349
0.3369
3⁄8
24
0.3750
0.3778
0.3803
0.3479
0.3484
0.3499
7⁄16
14
0.4375
0.4419
0.4449
0.3911
0.3916
0.3941
7⁄16
20
0.4375
0.4407
0.4437
0.4050
0.4055
0.4075
1⁄2
13
0.5000
0.5047
0.5077
0.4500
0.4505
0.4530
1⁄2
20
0.5000
0.5032
0.5062
0.4675
0.4680
0.4700
9⁄16
12
0.5625
0.5675
0.5705
0.5084
0.5089
0.5114
9⁄16
18
0.5625
0.5660
0.5690
0.5264
0.5269
0.5289
5⁄8
11
0.6250
0.6304
0.6334
0.5660
0.5665
0.5690
5⁄8
18
0.6250
0.6285
0.6315
0.5889
0.5894
0.5914
3⁄4
10
0.7500
0.7559
0.7599
0.6850
0.6855
0.6885
3⁄4
16
0.7500
0.7539
0.7579
0.7094
0.7099
0.7124
7⁄8
9
0.8750
0.8820
0.8860
0.8028
0.8038
0.8068
7⁄8
14
0.8750
0.8799
0.8839
0.8286
0.8296
0.8321
1
8
1.0000
1.0078
1.0118
0.9188
0.9198
0.9228
1
12
1.0000
1.0055
1.0095
0.9459
0.9469
0.9494
1
14
1.0000
1.0049
1.0089
0.9536
0.9546
0.9571
1 1⁄8
7
1.1250
1.1337
1.1382
1.0322
1.0332
1.0367
1 1⁄8
12
1.1250
1.1305
1.1350
1.0709
1.0719
1.0749
1 1⁄4
7
1.2500
1.2587
1.2632
1.1572
1.1582
1.1617
1 1⁄4
12
1.2500
1.2555
1.2600
1.1959
1.1969
1.1999
1 3⁄8
6
1.3750
1.3850
1.3895
1.2667
1.2677
1.2712
1 3⁄8
12
1.3750
1.3805
1.3850
1.3209
1.3219
1.3249
1 1⁄2
6
1.5000
1.5100
1.5145
1.3917
1.3927
1.3962
1 1⁄2
12
1.5000
1.5055
1.5100
1.4459
1.4469
1.4499
1 3⁄4
5
1.7500
1.7602
1.7657
1.6201
1.6216
1.6256
2
4 1⁄2
2.0000
2.0111
2.0166
1.8557
1.8572
1.8612

 

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