Tap-drill reference chart

228 sizes · ThreadRef · sample of the first 8 rows

Tap-drill reference chart. The drill-press sheet: the recommended tap drill for all 228 thread entries - metric coarse and fine, UNC, UNF, UNEF, UN and pipe - with the named drill, its size in millimetres and inches, and the thread engagement it actually produces.
Size	Pitch mm	TPI	Tap drill	Tap drill mm	Tap drill in	Engagement %
Metric coarse
M1 × 0.25	0.25	101.6	0.75 mm	0.75	0.0295	77
M1.2 × 0.25	0.25	101.6	0.95 mm	0.95	0.0374	77
M1.4 × 0.3	0.3	84.7	1.1 mm	1.1	0.0433	77
M1.6 × 0.35	0.35	72.6	1.25 mm	1.25	0.0492	77
M1.8 × 0.35	0.35	72.6	1.45 mm	1.45	0.0571	77
M2 × 0.4	0.4	63.5	1.6 mm	1.6	0.063	77
M2.5 × 0.45	0.45	56.4	2.05 mm	2.05	0.0807	77
M3 × 0.5	0.5	50.8	2.5 mm	2.5	0.0984	77

Tap drills are the standard hole for the stated engagement, computed as major − (percent × 0.0129904) × pitch and matched to the nearest standard fractional, number or letter drill.

Torque figures are estimates that depend on the stated nut-factor assumption. Verify against your fastener manufacturer's data and joint requirements before assembly.

Every figure on this chart is also free on its own size page - browse the full reference. Premium pays for the sheet, not the numbers.