Unified Thread Series 8 TPI ANSI/ASME B1.1

8-UN - Unified Extra Fine Thread, which is used for special purposes.
The flank angle is 60°.

Nominal
Diameter
Major
Diameter
Inch
Major
Diameter
mm
Tapping
Drill Size
mm
TPI Pitch
mm
1 1/16" - 8-UN 1.0625 26.987 24.000 8 3.175
1 1/8" - 8-UN 1.1250 28.575 25.500 8 3.175
1 3/16" - 8-UN 1.1875 30.162 27.200 8 3.175
1 1/4" - 8-UN 1.2500 31.750 28.800 8 3.175
1 5/16" - 8-UN 1.3125 33.337 30.300 8 3.175
1 3/8" - 8-UN 1.3750 34.925 31.900 8 3.175
1 7/16" - 8-UN 1.4375 36.512 33.500 8 3.175
1 1/2" - 8-UN 1.5000 38.100 35.100 8 3.175
1 9/16" - 8-UN 1.5625 39.688 36.700 8 3.175
1 5/8" - 8-UN 1.6250 41.275 38.300 8 3.175
1 11/16" - 8-UN 1.6875 42.862 39.900 8 3.175
1 3/4" - 8-UN 1.7500 44.450 41.400 8 3.175
1 13/16" - 8-UN 1.8125 46.037 43.000 8 3.175
1 7/8" - 8-UN 1.8750 47.625 44.600 8 3.175
1 15/16" - 8-UN 1.9375 49.212 46.200 8 3.175
2" - 8-UN 2.0000 50.800 47.800 8 3.175
2 1/8" - 8-UN 2.1250 53.975 51.000 8 3.175
2 1/4" - 8-UN 2.2500 57.150 54.100 8 3.175
2 3/8" - 8-UN 2.3750 60.325 57.300 8 3.175
2 1/2" - 8-UN 2.5000 63.500 60.500 8 3.175
2 5/8" - 8-UN 2.6250 66.675 64.700 8 3.175
2 3/4" - 8-UN 2.7500 69.850 66.800 8 3.175
2 7/8" - 8-UN 2.8750 73.025 70.000 8 3.175
3" - 8-UN 3.0000 76.200 73.200 8 3.175
3 1/8" - 8-UN 3.1250 79.375 76.400 8 3.175
3 1/4" - 8-UN 3.2500 82.550 79.500 8 3.175
3 3/8" - 8-UN 3.3750 85.725 82.700 8 3.175
3 1/2" - 8-UN 3.5000 88.900 85.900 8 3.175
3 5/8" - 8-UN 3.6250 92.075 89.000 8 3.175
3 3/4" - 8-UN 3.7500 95.250 92.300 8 3.175
3 7/8" - 8-UN 3.8750 98.425 95.400 8 3.175
4" - 8-UN 4.0000 101.600 98.600 8 3.175