Maker & Reference
Drill + Tap Size Calculator
Tap drill = nominal size - 1/TPI (for inch). Get the wrong size and threads strip, undersized, or stock breaks the tap.
Tap drill
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- Decimal (in)
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- Clearance drill
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- Thread depth (in)
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FAQ
What is "75% thread"? +
Industry standard — 75% engagement gives 95%+ of full thread strength with way less risk of broken taps. 100% threads only add ~5% strength but break taps constantly.
Tap drill vs clearance drill? +
Tap drill: for the part being threaded. Clearance drill: for the part the bolt passes through (oversized).