3/4-16 tap drill size
Use a 11/16" drill (0.6875 in) for a 3/4-16 cutting tap at 75% thread.
| Tap type | Drill | Decimal (in) |
|---|---|---|
| Cutting tap, 75% thread | 11/16" | 0.6875 |
| Cutting tap, 50% thread (hard material) | 45/64" | 0.7031 |
| Roll / form tap, 65% thread | 23/32 | 0.7188 |
| Helicoil / STI insert (3/4-16×1D) | 53/64" | 0.8281 |
- Pitch
- 1.5875 mm (16 TPI)
- Major Ø
- 0.7500
- Pitch Ø
- 0.7094
- Minor Ø
- 0.6733
Common questions
- What size drill for a 3/4-16 tap?
- Use a 11/16" drill (0.6875 in) for a 3/4-16 cutting tap at 75% thread.
- What drill for a 3/4-16 roll (form) tap?
- About 0.7224 in; the nearest standard drill is 23/32. Check your tap maker's table.
- What drill for a 3/4-16 Helicoil?
- Drill 53/64" (0.8281 in), then tap with the 3/4-16 STI tap.
Other UNF sizes
Drill sizes from Machinery's Handbook and ASME B1.1/B1.13M; roll tap sizes from the form-tap formula. Tap and insert makers' tables are authoritative.