Engineering Tools

Tap Drill & Clearance Drill Chart

Look up the correct tap drill (sized for ~75% thread engagement) and the clearance drill for common UNC, UNF and metric threads. Pick a thread for a quick readout, or filter the full chart.

Select a thread

Tap drill (75% thread)

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Clearance drill

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Full chart

Thread	Tap drill	in / mm	Clearance	in / mm

Tap drill sizes shown target roughly 75% thread engagement, the common general-purpose value; thinner or harder materials are often tapped at 50–65% to reduce tapping torque. Clearance drills are the standard "close/free fit" sizes. Verify against your material, thread class and the tap manufacturer's recommendation before machining.

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