UNEF Thread ANSI/ASME B1.1

UNEF - 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
N 12 - 32 UNEF 0.216 5.486 4.80 32 0.794
1/4" - 32 UNEF 0.250 6.350 5.70 32 0.794
5/16" - 32 UNEF 0.313 7.938 7.25 32 0.794
3/8" - 32 UNEF 0.375 9.525 8.85 32 0.794
7/16" - 28 UNEF 0.438 11.112 10.35 28 0.907
1/2" - 28 UNEF 0.500 12.700 11.80 28 0.907
9/16" - 24 UNEF 0.563 14.288 13.40 24 1.058
5/8" - 24 UNEF 0.625 15.875 15.00 24 1.058
11/16" - 24 UNEF 0.688 17.462 16.60 24 1.058
3/4" - 20 UNEF 0.750 19.050 18.00 20 1.270
13/16" - 20 UNEF 0.813 20.638 19.60 20 1.270
7/8" - 20 UNEF 0.875 22.225 21.15 20 1.270
15/16" - 20 UNEF 0.938 23.812 22.70 20 1.270
1" - 20 UNEF 1.000 25.400 24.30 20 1.270
1 1/16" - 18 UNEF 1.063 26.988 25.80 18 1.411
1 1/8" - 18 UNEF 1.125 28.575 27.35 18 1.411
1 1/4" - 18 UNEF 1.250 31.750 30.55 18 1.411
1 5/16" - 18 UNEF 1.313 33.338 32.10 18 1.411
1 3/8" - 18 UNEF 1.375 34.925 33.70 18 1.411
1 7/16" - 18 UNEF 1.438 36.512 35.30 18 1.411
1 1/2" - 18 UNEF 1.500 38.100 36.90 18 1.411
1 9/16" - 18 UNEF 1.563 39.688 38.55 18 1.411
1 5/8" - 18 UNEF 1.625 41.275 40.10 18 1.411
1 11/16" - 18 UNEF 1.688 42.862 41.60 18 1.411