Specifications of International Thread Standards

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
TPIPitch
mm
N 12 - 32 UNEF0.2165.4864.80320.794
1/4" - 32 UNEF0.2506.3505.70320.794
5/16" - 32 UNEF0.3137.9387.25320.794
3/8" - 32 UNEF0.3759.5258.85320.794
7/16" - 28 UNEF0.43811.11210.35280.907
1/2" - 28 UNEF0.50012.70011.80280.907
9/16" - 24 UNEF0.56314.28813.40241.058
5/8" - 24 UNEF0.62515.87515.00241.058
11/16" - 24 UNEF0.68817.46216.60241.058
3/4" - 20 UNEF0.75019.05018.00201.270
13/16" - 20 UNEF0.81320.63819.60201.270
7/8" - 20 UNEF0.87522.22521.15201.270
15/16" - 20 UNEF0.93823.81222.70201.270
1" - 20 UNEF1.00025.40024.30201.270
1 1/16" - 18 UNEF1.06326.98825.80181.411
1 1/8" - 18 UNEF1.12528.57527.35181.411
1 1/4" - 18 UNEF1.25031.75030.55181.411
1 5/16" - 18 UNEF1.31333.33832.10181.411
1 3/8" - 18 UNEF1.37534.92533.70181.411
1 7/16" - 18 UNEF1.43836.51235.30181.411
1 1/2" - 18 UNEF1.50038.10036.90181.411
1 9/16" - 18 UNEF1.56339.68838.55181.411
1 5/8" - 18 UNEF1.62541.27540.10181.411
1 11/16" - 18 UNEF1.68842.86241.60181.411
UNEF Thread