美制螺丝规格表，一人一份，随用随查！

周升霞66

美制外螺纹（2A）常用螺丝规格极限尺寸表（粗牙）
公称尺寸和每英寸牙数
螺纹系列代号
大径极限
中径极限
小径max
螺胚直径



最小
最大
最小
最大
最小
最大



8-32
UNC
0.1571
0.1631
0.1399
0.1428
0.1248
3.58
3.61
(0.164-32)
3.9903
4.1427
3.5535
3.6271
3.1699



10-24
0.1818
0.1890
0.1586
0.1619
0.1379
4.07
4.10

(0.190-24)
4.6177
4.8006
4.0284
4.1123
3.5027



12-24
0.2078
0.2150
0.1845
0.1879
0.1639
4.72
4.75

(0.216-24)
5.2781
5.4610
4.6863
4.7727
4.1631



1/4-20
0.2408
0.2489
0.2127
0.2164
0.1876
5.45
5.48

(0.250-20)
6.1163
6.3221
5.4026
5.4966
4.7650



5/16-18
0.3026
0.3113
0.2712
0.2752
0.2431
6.94
6.98

(0.3175-18)
7.6860
7.9070
6.8885
6.9901
6.1747



3/8-16
0.3643
0.3737
0.3287
0.3331
0.2970
8.40
8.44

(0.375-16)
9.2532
9.4920
8.3490
8.4607
7.5438



7/16-14
0.4258
0.4361
0.3850
0.3897
0.3485
9.83
9.87

(0.4375-14)
10.8153
11.0769
9.7790
9.8984
8.8519



1/2-13
0.4876
0.4985
0.4435
0.4485
0.4041
11.34
11.38

(0.50-13)
12.3850
12.6619
11.2649
11.3919
10.2641



9/16-12
0.5495
0.5609
0.5016
0.5068
0.4587
12.80
12.84

(0.5625-12)
13.9573
14.2469
12.7406
12.8727
11.6510



5/8-11
0.6113
0.6234
0.5589
0.5644
0.5119
14.27
14.32

(0.625-11)
15.5270
15.8344
14.1961
14.3358
13.0023



3/4-10
0.7353
0.7482
0.6773
0.6832
0.6255
17.28
17.33

(0.750-10)
18.6766
19.0043
17.2034
17.3533
15.8877



7/8-9
0.8592
0.8731
0.7946
0.8009
0.7368
20.27
20.32

(0.875-9)
21.8237
22.1767
20.1828
20.3429
18.7147



1"-8
0.9830
0.9980
0.9100
0.9168
0.8446
23.22
23.27

(1.000-8)
24.9682
25.3492
23.1140
23.2867
21.4528












美制外螺纹（2A）常用螺丝规格极限尺寸表（细牙）
公称尺寸和每英寸牙数
螺纹系列代号
大径极限
中径极限
小径max
螺胚直径



最小
最大
最小
最大
最小
最大



8-36
UNF
0.1577
0.1632
0.1424
0.1452
0.1291
3.65
3.67
(0.164-36)
4.0056
4.1453
3.6170
3.6881
3.2791



10-32
0.1831
0.1891
0.1658
0.1688
0.1508
4.24
4.27

(0.190-32)
4.6507
4.8031
4.2113
4.2875
3.8303



12-28
0.2085
0.2150
0.1886
0.1918
0.1712
4.82
4.85

(0.216-28)
5.2959
5.4610
4.7904
4.8717
4.3485



1/4-28
0.2425
0.2490
0.2225
0.2258
0.2052
5.69
5.71

(0.250-28)
6.1595
6.3246
5.6515
5.7353
5.2121



5/16-24
0.3042
0.3114
0.2806
0.2843
0.2603
7.17
7.20

(0.3175-24)
7.7267
7.9096
7.1272
7.2212
6.6116



3/8-24
0.3667
0.3739
0.3430
0.3468
0.3228
8.75
8.78

(0.375-24)
9.3142
9.4971
8.7122
8.8087
8.1991



7/16-20
0.4281
0.4362
0.3995
0.4037
0.3749
10.19
10.23

(0.4375-20)
10.8737
11.0795
10.1473
10.2540
9.5225



1/2-20
0.4906
0.4987
0.4619
0.4662
0.4374
11.78
11.82

(0.50-20)
12.4612
12.6670
11.7323
11.8415
11.1100



9/16-18
0.5524
0.5611
0.5205
0.5250
0.4929
13.27
13.31

(0.5625-18)
14.0310
14.2519
13.2207
13.3350
12.5197



5/8-18
0.6149
0.6236
0.5828
0.5875
0.5554
14.85
14.89

(0.625-18)
15.6185
15.8394
14.8031
14.9225
14.1072



3/4-16
0.7391
0.7485
0.7029
0.7079
0.6718
17.91
17.95

(0.750-16)
18.7731
19.0119
17.8537
17.9807
17.0637



7/8-14
0.8631
0.8734
0.8216
0.8270
0.7858
20.93
20.97

(0.875-14)
21.9227
22.1844
20.8686
21.0058
19.9593



1"-12
0.9868
0.9982
0.9382
0.9441
0.8960
23.90
23.95

(1.000-12)
25.0647
25.3543
23.8303
23.9801
22.7584













美制内螺纹（2B）常用螺丝规格极限尺寸表（粗牙）
公称尺寸和每英寸牙数
螺纹系列代号
小径极限
中径极限
大径min
底孔直径



最小
最大
最小
最大
最小
最大



8-32
UNC
0.1300
0.1390
0.1437
0.1475
0.1640
3.40
3.50
(0.164-32)
3.3020
3.5306
3.6500
3.7465
4.1656



10-24
0.1450
0.1560
0.1629
0.1672
0.1900
3.75
3.90

(0.190-24)
3.6830
3.9624
4.1377
4.2469
4.8260



12-24
0.1710
0.1810
0.1889
0.1933
0.2160
4.40
4.55

(0.216-24)
4.3434
4.5974
4.7981
4.9098
5.4864



1/4-20
0.1960
0.2070
0.2175
0.2224
0.2500
5.05
5.20

(0.250-20)
4.9784
5.2578
5.5245
5.6490
6.3500



5/16-18
0.2520
0.2650
0.2764
0.2817
0.3125
6.45
6.60

(0.3175-18)
6.4008
6.7310
7.0206
7.1552
7.9375



3/8-16
0.3070
0.3210
0.3344
0.3401
0.3750
7.85
8.00

(0.375-16)
7.7978
8.1534
8.4938
8.6385
9.5250



7/16-14
0.3600
0.3760
0.3911
0.3972
0.4375
9.20
9.40

(0.4375-14)
9.1440
9.5504
9.9339
10.0889
11.1125



1/2-13
0.4170
0.4340
0.4500
0.4565
0.5000
10.65
10.90

(0.50-13)
10.5918
11.0236
11.4300
11.5951
12.7000



9/16-12
0.4720
0.4900
0.5084
0.5152
0.5625
12.05
12.30

(0.5625-12)
11.9888
12.4460
12.9134
13.0861
14.2875



5/8-11
0.5270
0.5460
0.5660
0.5732
0.6250
13.45
13.70

(0.625-11)
13.3858
13.8684
14.3764
14.5593
15.8750



3/4-10
0.6420
0.6630
0.6850
0.6927
0.7500
16.40
16.70

(0.750-10)
16.3068
16.8402
17.3990
17.5946
19.0500



7/8-9
0.7550
0.7780
0.8028
0.8110
0.8750
19.30
19.60

(0.875-9)
19.1770
19.7612
20.3911
20.5994
22.2250



1"-8
0.8650
0.8900
0.9188
0.9276
1.0000
22.10
22.40

(1.000-8)
21.9710
22.6060
23.3375
23.5610
25.4000













美制内螺纹（2B）常用螺丝规格极限尺寸表（细牙）
公称尺寸和每英寸牙数
螺纹系列代号
小径极限
中径极限
大径min
底孔直径



最小
最大
最小
最大
最小
最大



8-36
UNF
0.1340
0.1420
0.1460
0.1496
0.1640
3.45
3.67
(0.164-36)
3.4036
3.6068
3.7084
3.7998
4.1656



10-32
0.1560
0.1640
0.1697
0.1736
0.1900
4.00
4.27

(0.190-32)
3.9624
4.1656
4.3104
4.4094
4.8260



12-28
0.1770
0.1860
0.1928
0.1970
0.2160
4.55
4.85

(0.216-28)
4.4958
4.7244
4.8971
5.0038
5.4864



1/4-28
0.2110
0.2200
0.2268
0.2311
0.2500
5.40
5.71

(0.250-28)
5.3594
5.5880
5.7607
5.8699
6.3500



5/16-24
0.2670
0.2770
0.2854
0.2902
0.3125
6.85
7.20

(0.3175-24)
6.7818
7.0358
7.2492
7.3711
7.9375



3/8-24
0.3300
0.3400
0.3479
0.3528
0.3750
8.45
8.78

(0.375-24)
8.3820
8.6360
8.8367
8.9611
9.5250



7/16-20
0.3830
0.3950
0.4050
0.4104
0.4375
9.85
10.23

(0.4375-20)
9.7282
10.0330
10.2870
10.4242
11.1125



1/2-20
0.4460
0.4570
0.4675
0.4731
0.5000
11.40
11.82

(0.50-20)
11.3284
11.6078
11.8745
12.0167
12.7000



9/16-18
0.5020
0.5150
0.5264
0.5323
0.5625
12.85
13.31

(0.5625-18)
12.7508
13.0810
13.3706
13.5204
14.2875



5/8-18
0.5650
0.5780
0.5889
0.5949
0.6250
14.45
14.89

(0.625-18)
14.3510
14.6812
14.9581
15.1105
15.8750



3/4-16
0.6820
0.6960
0.7094
0.7159
0.7500
17.40
17.95

(0.750-16)
17.3228
17.6784
18.0188
18.1839
19.0500



7/8-14
0.7980
0.8140
0.8286
0.8356
0.8750
20.35
20.97

(0.875-14)
20.2692
20.6756
21.0464
21.2242
22.2250



1"-12
0.9100
0.9280
0.9459
0.9535
1.0000
23.90
23.95

(1.000-12)
23.1140
23.5712
24.0259
24.2189
25.4000