Tap drill charts

The cut tap drill for each standard thread at OSG's 65–70% of thread for general work. Tap a thread for every drill from 50% to 85%, form tap sizes, the thread's dimensions and a 3-wire check, or use the calculator for any thread and material.

Unified inch (ASME B1.1)

Unified inch threads with their cut tap drills
Size	UNC	UNF	UNEF
#0	—	#0-803/64	—
#1	#1-64#53	#1-72#53	—
#2	#2-56#50	#2-64#49	—
#3	#3-48#46	#3-56#45	—
#4	#4-40#43	#4-483/32	—
#5	#5-40#37	#5-44#37	—
#6	#6-32#34	#6-40#32	—
#8	#8-32#29	#8-36#28	—
#10	#10-24#23	#10-32#20	—
#12	#12-24#15	#12-28#13	#12-32#12
1/4	1/4-20#5	1/4-287/32	1/4-32#2
5/16	5/16-1817/64	5/16-24J	5/16-329/32
3/8	3/8-16P	3/8-24R	3/8-32S
7/16	7/16-143/8	7/16-2025/64	7/16-2813/32
1/2	1/2-137/16	1/2-2029/64	1/2-2815/32
9/16	9/16-1231/64	9/16-1833/64	9/16-2417/32
5/8	5/8-1135/64	5/8-1837/64	5/8-2419/32
3/4	3/4-1021/32	3/4-1611/16	3/4-2045/64
7/8	7/8-925/32	7/8-1413/16	7/8-2053/64
1	1-857/64	1-1259/64	1-2061/64
1-1/8	1-1/8-71	1-1/8-121-3/64	1-1/8-181-5/64
1-1/4	1-1/4-71-1/8	1-1/4-121-11/64	1-1/4-181-13/64
1-3/8	1-3/8-61-15/64	1-3/8-121-19/64	1-3/8-181-21/64
1-1/2	1-1/2-61-23/64	1-1/2-121-27/64	1-1/2-181-29/64
1-3/4	1-3/4-51-37/64	—	—
2	2-4.51-13/16	—	—

ISO metric (ISO 261)

ISO metric threads with their cut tap drills
Size	Coarse	Fine
M1	× 0.250.8 mm	× 0.20.8 mm
M1.2	× 0.251 mm	× 0.21 mm
M1.6	× 0.351.3 mm	× 0.21.4 mm
M2	× 0.41.6 mm	× 0.251.8 mm
M2.5	× 0.452.1 mm	× 0.352.2 mm
M3	× 0.52.6 mm	× 0.352.7 mm
M3.5	× 0.63 mm	× 0.353.2 mm
M4	× 0.73.4 mm	× 0.53.6 mm
M5	× 0.84.3 mm	× 0.54.6 mm
M6	× 15.1 mm	× 0.755.3 mm
M8	× 1.256.9 mm	× 17.1 mm × 0.757.3 mm
M10	× 1.58.7 mm	× 1.258.9 mm × 19.1 mm × 0.759.3 mm
M12	× 1.7510.5 mm	× 1.510.7 mm × 1.2510.9 mm × 111.1 mm
M14	× 212.2 mm	× 1.512.7 mm × 1.2512.9 mm × 113 mm
M16	× 214 mm	× 1.514.5 mm × 115 mm
M18	× 2.516 mm	× 216 mm × 1.516.5 mm × 117 mm
M20	× 2.518 mm	× 218 mm × 1.518.5 mm × 119 mm
M22	× 2.520 mm	× 220 mm × 1.520.5 mm × 121 mm
M24	× 321.5 mm	× 222 mm × 1.522.5 mm × 123 mm
M27	× 324.5 mm	× 225 mm × 1.525.5 mm × 126 mm
M30	× 3.527 mm	× 327.5 mm × 228 mm × 1.528.5 mm × 129 mm
M33	× 3.530 mm	× 330.5 mm × 231 mm × 1.531.5 mm
M36	× 432.5 mm	× 333.5 mm × 234 mm × 1.534.5 mm
M39	× 435.5 mm	× 336.5 mm × 237 mm × 1.537.5 mm
M42	× 4.538 mm	× 438.5 mm × 339.5 mm × 240 mm × 1.540.5 mm
M45	× 4.541 mm	× 441.5 mm × 342.5 mm × 243 mm × 1.543.5 mm
M48	× 543.5 mm	× 444.5 mm × 345.5 mm × 246 mm × 1.546.5 mm