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British Standard Whitworth (B.S.W.)

Thread Form

Whitworth Thread Form
  • p = Pitch = 1/TPI
  • h = Basic Depth of Thread = 0.640327p
  • r = Basic Radius = 0.137329p

Thread Tables

Nominal Diameter T.P.I. Basic Depth of Thread Basic Major Diameter Basic Effective Diameter Basic Minor Diameter Tapping Drill Clearing Drill
(inch) (n/a) (inch) (inch) (inch) (inch) (mm) (mm)
1/16 60 0.0107 0.0625 0.0518 0.0411 1.2 1.65
3/32 48 0.0133 0.0938 0.0805 0.0672 1.85 2.5
1/8 40 0.016 0.125 0.109 0.093 2.55 3.3
5/32 32 0.02 0.1562 0.1362 0.1162 3.2 4.1
3/16 24 0.0267 0.1875 0.1608 0.1341 3.7 4.9
7/32 24 0.0267 0.2188 0.1921 0.1654 4.5 5.7
1/4 20 0.032 0.25 0.218 0.186 5.1 6.5
5/16 18 0.0356 0.3125 0.2769 0.2413 6.5 8.1
3/8 16 0.04 0.375 0.335 0.295 7.9 9.7
7/16 14 0.0457 0.4375 0.3918 0.3461 9.3 11.3
1/2 12 0.0534 0.5 0.4466 0.3932 10.5 13
9/16 12 0.0534 0.5625 0.5091 0.4557 12.1 14.5
5/8 11 0.0582 0.625 0.5668 0.5086 13.5 16.25
11/16 11 0.0582 0.6875 0.6293 0.5711 15 17.75
3/4 10 0.064 0.75 0.686 0.622 16.25 19.25
13/16 10 0.064 0.8125 0.7485 0.6845 18 21
7/8 9 0.0711 0.875 0.8039 0.7328 19.25 22.5
15/16 9 0.0711 0.9375 0.8664 0.7953 20.75 24
1 8 0.08 1 0.92 0.84 22 25.75
1,1/8 7 0.0915 1.125 1.0335 0.942 24.75 29
1,1/4 7 0.0915 1.25 1.1585 1.067 28 32
1,3/8 6 0.1067 1.375 1.2683 1.1616 30.25 35.5
1,1/2 6 0.1067 1.5 1.3933 1.2866 33.5 38.5
1,5/8 5 0.1281 1.625 1.4969 1.3688 35.5 41.5
1,3/4 5 0.1281 1.75 1.6219 1.4938 39 45
1,7/8 4,1/2 0.1423 1.875 1.7327 1.5904 41.5 48
2 4,1/2 0.1423 2 1.8577 1.7154 44 51
2,1/4 4 0.1601 2.25 2.0899 1.9298 51 58
2,1/2 4 0.1601 2.5 2.3399 2.1798 57 64
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Last modified: SolFlu  Sun, 28 Jun 2009 02:58:14 GMT