Threads / Size reference
13/16-20 UNEF
13/16-20 has a nominal outside diameter of 20.6375 mm and a 1.27 mm pitch.
20.6375 mm
1.27 mm pitch
Nominal dimensions; no class allowances or acceptance limits applied. Diameter is in inches; the number after the dash is TPI.
nearby diameter comparison
13/16-20 vs 7/8-20
There is no second pitch at this diameter in the directory. Compare the nearby 7/8-20 UNEF: its nominal diameter differs by 1.5875 mm. It is not a replacement.
Swipe to compare both sizes →
| Property | 13/16-20 UNEF | 7/8-20 UNEF |
|---|---|---|
| Nominal diameter · inDifferent | 0.8125 | 0.875 |
| Nominal diameter · mmDifferent | 20.6375 | 22.225 |
| Threads per inch | 20 | 20 |
| Pitch · mm | 1.27 | 1.27 |
Tapping-hole evidence for 13/16-20
No reviewed chart row for 13/16-20 UNEF
No UNEF drill row or UNEF-specific equation scope has been reviewed. Use the exact tap maker’s data; a UNC/UNF drill at the same diameter is not a substitute.
Need acceptance limits?
The complete class and applicable drawing requirements are needed. These nominal values are not maximum/minimum inspection limits.
Part has no marking?
Measure the correct diameter and pitch, then compare candidates across metric and inch systems.
Basis for this size
Nominal designation and family transcribed from the live directory on 2026-10-19; unit conversions are calculated using exactly 25.4 mm/in. No matching drill row has been reviewed for this exact size. Paid standard limit tables have not been reviewed.