Specifications of International Thread Standards

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
TPIPitch
mm
1 1/16" - 8-UN1.062526.98724.00083.175
1 1/8" - 8-UN1.125028.57525.50083.175
1 3/16" - 8-UN1.187530.16227.20083.175
1 1/4" - 8-UN1.250031.75028.80083.175
1 5/16" - 8-UN1.312533.33730.30083.175
1 3/8" - 8-UN1.375034.92531.90083.175
1 7/16" - 8-UN1.437536.51233.50083.175
1 1/2" - 8-UN1.500038.10035.10083.175
1 9/16" - 8-UN1.562539.68836.70083.175
1 5/8" - 8-UN1.625041.27538.30083.175
1 11/16" - 8-UN1.687542.86239.90083.175
1 3/4" - 8-UN1.750044.45041.40083.175
1 13/16" - 8-UN1.812546.03743.00083.175
1 7/8" - 8-UN1.875047.62544.60083.175
1 15/16" - 8-UN1.937549.21246.20083.175
2" - 8-UN2.000050.80047.80083.175
2 1/8" - 8-UN2.125053.97551.00083.175
2 1/4" - 8-UN2.250057.15054.10083.175
2 3/8" - 8-UN2.375060.32557.30083.175
2 1/2" - 8-UN2.500063.50060.50083.175
2 5/8" - 8-UN2.625066.67564.70083.175
2 3/4" - 8-UN2.750069.85066.80083.175
2 7/8" - 8-UN2.875073.02570.00083.175
3" - 8-UN3.000076.20073.20083.175
3 1/8" - 8-UN3.125079.37576.40083.175
3 1/4" - 8-UN3.250082.55079.50083.175
3 3/8" - 8-UN3.375085.72582.70083.175
3 1/2" - 8-UN3.500088.90085.90083.175
3 5/8" - 8-UN3.625092.07589.00083.175
3 3/4" - 8-UN3.750095.25092.30083.175
3 7/8" - 8-UN3.875098.42595.40083.175
4" - 8-UN4.0000101.60098.60083.175
8-UN Thread