buncha/engineering/tapdrill

Tap Drill Chart

Tap	Drill	Inch	mm	Std
#4-40	#43	0.0890	2.26	UNC
#6-32	#36	0.1065	2.71	UNC
#8-32	#29	0.1360	3.45	UNC
#10-24	#25	0.1495	3.80	UNC
1/4-20	#7	0.2010	5.11	UNC
5/16-18	F	0.2570	6.53	UNC
3/8-16	5/16	0.3125	7.94	UNC
7/16-14	U	0.3680	9.35	UNC
1/2-13	27/64	0.4219	10.72	UNC
5/8-11	17/32	0.5312	13.49	UNC
3/4-10	21/32	0.6562	16.67	UNC
1-8	7/8	0.8750	22.23	UNC
#4-48	#42	0.0935	2.37	UNF
#6-40	#33	0.1130	2.87	UNF
#8-36	#29	0.1360	3.45	UNF
#10-32	#21	0.1590	4.04	UNF
1/4-28	#3	0.2130	5.41	UNF
5/16-24	I	0.2720	6.91	UNF
3/8-24	Q	0.3320	8.43	UNF
7/16-20	25/64	0.3906	9.92	UNF
1/2-20	29/64	0.4531	11.51	UNF
5/8-18	37/64	0.5781	14.68	UNF
3/4-16	11/16	0.6875	17.46	UNF
M2×0.4	1.6 mm	0.0630	1.60	ISO
M2.5×0.45	2.05 mm	0.0807	2.05	ISO
M3×0.5	2.5 mm	0.0984	2.50	ISO
M4×0.7	3.3 mm	0.1299	3.30	ISO
M5×0.8	4.2 mm	0.1654	4.20	ISO
M6×1.0	5.0 mm	0.1969	5.00	ISO
M8×1.25	6.8 mm	0.2677	6.80	ISO
M10×1.5	8.5 mm	0.3346	8.50	ISO
M12×1.75	10.2 mm	0.4016	10.20	ISO
M14×2.0	12.0 mm	0.4724	12.00	ISO
M16×2.0	14.0 mm	0.5512	14.00	ISO
M20×2.5	17.5 mm	0.6890	17.50	ISO

75% thread engagement — the shop standard. Going to 100% (theoretical max) means smaller drill = more torque on the tap = broken taps. Drop to 65% if your material is hard or the tap is small. Click any row to copy the full spec.

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About Tap Drill Chart

UNC, UNF, and ISO metric tap-drill sizes at 75% thread engagement.

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