Tap drill answer
What Size Drill Bit for #10-32 UNF Tap?
For a #10-32 UNF tap, a common reference drill is #21, which is 0.1590 in or 4.04 mm. Verify the value for material, tap type, and required thread engagement.
#10-32 UNF tap drill quick answer
Method: Named UNC and UNF drill sizes are maintained as common cutting-tap reference values and checked against manufacturer ranges. Reviewed 2026-07-24.
How to use this #10-32 UNF value
This page gives a common chart value for hand tapping and general reference work. Use a different value when your drawing specifies a thread class, percent thread, forming tap, pipe thread, thin wall, brittle material, or plated/coated part.
- Start with the listed drill size.
- Confirm the tap type and thread engagement target.
- Test in scrap material when fit matters.
- Use cutting fluid and proper chip clearing for deeper holes.
What drill bit size for 10-32 tap?
A common chart value for a #10-32 UNF tap is a #21 drill, which is 0.1590 in or about 4.04 mm. This is the fine-thread #10 row, not the same drill as #10-24.
10-32 tap drill diameter
The #21 drill diameter is 0.1590 in. Use the decimal value when comparing nearby numbered, fractional, or metric drills, then verify against the chart row before cutting.
Is 10-32 tap drill size the same as 10-24?
No. #10-32 UNF commonly uses #21, while #10-24 UNC commonly uses #25. The two taps share the same nominal screw size, but the thread count changes the hole size.
10-32 tap drill size in mm
#21 converts to about 4.04 mm. If you only have metric drills, compare the exact decimal to the nearest available drill and decide whether the fit is acceptable for the material and thread engagement.