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Table 329 - Machine Screw Sizes

Size

Threads Per Inch

Basic Pitch Dia.

Pitch Diameter Limits

NC

NF

NS

Major Diameter

H1 Limit

H2 Limit

H3 Limit

H7 Limit

UNC

UNF

UNS

Basic

Min.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

0 1 1 2 2

– 64 – 56 –

80 – 72 – 64

– – – – –

.0600 .0730 .0730 .0860 .0860

.0605 .0736 .0736 .0867 .0866

.0616 .0750 .0748 .0883 .0880

.0519 .0629 .0640 .0744 .0759

.0519 .0629 .0640 .0744 –

.0524 .0634 .0645 .0749 –

.0524 .0634 .0645 .0749 .0764

.0529 .0639 .0650 .0754 .0769

– – – – –

– – – – –

– – – – –

– – – – –

3 3 4 4 4

48 – – 40 –

– 56 – – 48

– – 36 – –

.0990 .0990 .1120 .1120 .1120

.0999 .0997 .1135 .1133 .1129

.1017 .1013 .1156 .1152 .1147

.0855 .0874 .0940 .0958 .0985

.0855 .0874 – .0958 .0985

.0860 .0879 – .0963 .0990

.0860 .0879 .0945 .0963 .0990

.0865 .0884 .0950 .0968 .0995

– – – – –

– – – – –

– – – – –

– – – – –

5 5 6 6 8

40 – 32 – 32

– 44 – 40 –

– – – – –

.1250 .1250 .1380 .1380 .1640

.1263 .1263 .1401 .1393 .1661

.1282 .1280 .1421 .1412 .1681

.1088 .1102 .1177 .1218 .1437

.1088 – .1177 .1218 .1437

.1093 – .1182 .1223 .1442

.1093 .1107 .1182 .1223 .1442

.1098 .1112 .1187 .1228 .1447

– – .1187 – .1447

– – .1192 – .1452

– – .1207 – .1467

– – .1212 – .1472

8 10 10 12 12

– 24 – 24 –

36 – 32 – 28

– – – – –

.1640 .1900 .1900 .2160 .2160

.1655 .1927 .1921 .2187 .2183

.1676 .1954 .1941 .2214 .2206

.1460 .1629 .1697 .1889 .1928

– .1629 .1697 – –

– .1634 .1702 – –

.1465 .1634 .1702 – –

.1470 .1639 .1707 – –

– .1639 .1707 .1899 .1938

– .1644 .1712 .1904 .1943

– .1659 .1727 – –

– .1664 .1732 – –

Table 327 - Fractional Sizes

Size

Threads Per Inch

Basic Pitch Dia.

Pitch Diameter Limits

NC

NF

NS

Major Diameter

H1 Limit

H2 Limit

H3 Limit

H4 Limit

H5 Limit

H6 Limit

UNC

UNF

UNS

Basic

Min.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

1/4 1/4 5/16 5/16 3/8

20 – 18 – 16

– 28 – 24 –

– – – – –

.2500 .2500 .3125 .3125 .3750

.2533 .2523 .3161 .3152 .3790

.2565 .2546 .3197 .3179 .3831

.2175 .2268 .2764 .2854 .3344

.2175 .2268 .2764 .2854 .3344

.2180 .2273 .2769 .2859 .3349

.2180 .2273 .2769 .2859 .3349

.2185 .2278 .2774 .2864 .3354

.2185 .2278 .2774 .2864 .3354

.2190 .2283 .2779 .2869 .3359

– .2283 – .2869 –

– .2288 – .2874 –

.2195 – .2784 – .3364

.2200 – .2789 – .3369

– – – – –

– – – – –

3/8 7/16 7/16 1/2 1/2

– 14 – 13 –

24 – 20 – 20

– – – – –

.3750 .4375 .4375 .5000 .5000

.3777 .4422 .4408 .5050 .5033

.3804 .4468 .4440 .5100 .5065

.3479 .3911 .4050 .4500 .4675

.3479 – – .4500 .4675

.3484 – – .4505 .4680

.3484 .3916 – .4505 .4680

.3489 .3921 – .4510 .4685

.3489 .3921 .4060 .4510 .4685

.3494 .3926 .4065 .4515 .4690

.3494 – – – –

.3499 – – – –

– .3931 .4070 .4520 .4695

– .3936 .4075 .4525 .4700

– – – – –

– – – – –

9/16 9/16 5/8 5/8 11/16

12 – 11 – –

– 18 – 18 –

– – – – 11

.5625 .5625 .6250 .6250 .6875

.5679 .5661 .6309 .6286 .6934

.5733 .5697 .6368 .6322 .6993

.5084 .5264 .5660 .5889 .6285

– – – – –

– – – – –

– .5269 .5665 .5894 –

– .5274 .5670 .5899 –

.5094 .5274 .5670 .5899 .6295

.5099 .5279 .5675 .5904 .6300

– – – – –

– – – – –

.5104 .5284 .5680 .5909 –

.5109 .5289 .5685 .5914 –

– – – – –

– – – – –

11/16 3/4 3/4 7/8 7/8

– 10 – 9 –

– – 16 – 14

16 – – – –

.6875 .7500 .7500 .8750 .8750

.6915 .7565 .7540 .8822 .8797

.6956 .7630 .7581 .8894 .8843

.6469 .6850 .7094 .8028 .8286

– – .7094 – –

– - .7099 – -

– .6855 .7099 – .8291

– .6860 .7099 – .8296

.6479 .6860 .7104 – –

.6484 .6865 .7109 – –

– – – .8043 .8301

– – – .8048 .8306

– .6870 .7114 – –

– .6875 .7119 – –

– – – .8053 –

– – – .8058 –

1 1 1

8 – –

– 12 –

– – 14

1.0000 1.0000 1.0000

1.0081 1.0054 1.0047

1.0162 1.0108 1.0093

.9188 .9459 .9536

– – –

– – –

– – –

– – –

– – –

– – –

.9203 .9474 .9551

.9208 .9479 .9556

– – –

– – –

.9213 – –

.9218 – –

GENERAL NOTE: All Dimensions are given in inches. Lead Tolerance: A maximum lead deviation of ±0.0005 in. within any two threads not farther apart than 1 in. is permitted.