Sellers Thread

In 1864, a committee of the Franklin-Institute in the USA presented a thread which was named after its creator, William Sellers, in 1868.
The flank angle is 60°.

Nominal
Diameter
Major
Diameter
Inch
Major
Diameter
mm
Tapping
Drill Size
mm
TPI Pitch
mm
1/4" - 20 0.250 6.350 4.72 20 1.270
5/16" - 18 0.313 7.938 6.13 18 1.411
3/8" - 16 0.375 9.525 7.49 16 1.587
7/16" - 14 0.438 11.113 8.79 14 1.814
1/2" - 13 0.500 12.700 9.99 13 1.954
5/8" - 11 0.625 15.875 12.92 11 2.309
3/4" - 10 0.750 19.050 15.80 10 2.540
7/8" - 9 0.875 22.225 18.61 9 2.822
1" - 8 1.000 25.400 21.33 8 3.175
1 1/8" - 7 1.125 28.575 23.93 7 3.628
1 1/4" - 7 1.250 31.750 27.10 7 3.628
1 3/8" - 6 1.375 34.925 29.50 6 4.233
1 1/2" - 6 1.500 38.100 32.68 6 4.233
1 5/8" - 5 1/2 1.625 41.275 34.77 5.5 4.618
1 3/4" - 5 1.750 44.450 37.94 5 5.080
1 7/8" - 5 1.875 47.625 40.40 5 5.080
2" - 4 1/2 2.000 50.800 43.57 4.5 5.644
2 1/4" - 4 1/2 2.250 57.150 49.02 4.5 5.644
2 1/2" - 4 2.500 63.500 55.37 4 6.350
2 3/4" - 4 2.750 69.850 60.55 4 6.350
3" - 3 1/2 3.000 76.200 66.90 3.5 7.257
3 1/4" - 3 1/2 3.250 82.550 72.57 3.5 7.257
3 1/2" - 3 1/4 3.500 88.900 78.92 3.25 7.815
3 3/4" - 3 3.750 95.250 84.40 3 8.467
4" - 3 4.000 101.600 90.75 3 8.467
5" - 2 1/2 5.500 127.000 115.20 2.5 10.160
6" - 2 1/4 6.000 152.400 139.40 2.25 11.289