Whitworth's Standard Screw Threads for Bolts (in)

Written by Matt Milbury. Posted in Thread Datasheets

Diameter

of

Fractional

Sizes

Bolt

Decimal

Sizes

Number

of Threads

per Inch

Diameter

at Bottom

of Thread

Distance

Across

Flat

Distance

Across

Corners

Thickness

of

Bolt Head

Thickness

of

Nut

1/4 0.25 20 0.1860 0.525 0.6062 0.2187 1/4
5/16 0.3125 18 0.2414 0.6014 0.6944 0.2734 5/16
3/8 0.375 16 0.2950 0.7094 0.8191 0.3281 3/8
7/16 0.4375 14 0.3460 0.8204 0.9473 0.3828 7/16
1/2 0.5 12 0.3933 0.9191 1.0612 0.4375 1/2
9/16 0.5625 12 0.4558 1.011 1.1674 0.4921 9/16
5/8 0.625 11 0.5086 1.101 1.2713 0.5468 5/8
11/16 0.6875 11 0.5711 1.2011 1.3869 0.6015 11/16
3/4 0.75 10 0.6219 1.3012 1.5024 0.6562 3/4
13/16 0.8125 10 0.6844 1.39 1.6050 0.7109 13/16
7/8 0.875 9 0.7327 1.4788 1.7075 0.7656 7/8
1 1.1 8 0.8399 1.6701 1.9284 0.875 1
1 1/8 1.125 7 0.9420 1.8605 2.1483 0.9843 1 1/8
1 1/4 1.25 7 1.0670 2.0483 2.3651 1.0937 1 1/4
1 3/8 1.375 6 1.1616 2.2146 2.5571 1.2031 1 3/8
1 1/2 1.5 6 1.2866 2.4134 2.7867 1.3125 1 1/2
1 5/8 1.625 5 1.3689 2.5763 2.9748 1.4218 1 5/8
1 3/4 1.75 5 1.4939 2.7578 3.1844 1.5312 1 3/4
2 2.0 4.5 1.7154 3.1491 3.6362 1.75 2
2 1/4 2.25 4 1.9298 3.546 4.0945 1.9687 2 1/4
2 1/2 2.5 4 2.1798 3.984 4.4964 2.1875 2 1/2
2 3/4 2.75 3.5 2.3841 4.101 4.8278 2.4062 2 3/4
3 3.0 3.5 2.6341 4.531 5.2319 2.625 3
3 1/4 3.25 3.25 2.8560 4.85 5.6002 2.843 3 1/4
3 1/2 3.5 3.25 3.1060 5.175 5.9755 3.062 3 1/2
3 3/4 3.75 3 3.3231 5.55 6.4085 3.281 3 3/4
4 4.0 3 3.5731 5.95 6.8704 3.5 4
4 1/2 4.5 2.875 4.0546 6.825 7.8819 3.937 4 1/2
5 5.0 2.75 4.5343 7.8 9.0066 4.375 5
5 1/2 5.5 2.625 5.0121 8.85 10.2190 4.812 5 1/2
6 6.0 2.5 5.4877 10 11.5470 5.25 6