Tap Drill Sizes / Decimal Equivalents

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These tap drill sizes are for cutting taps at approximately 75% of threads.

Inch Tap Drill Sizes & Decimal Equivalents

Drill Inch	Decimal	Tap Size
#80	.0135
#79	.0145
1/64	.01563
#78	.016
#77	.018
#76	.020
#75	.021
#74	.0225
#73	.024
#72	.025
#71	.026
#70	.028
#69	.0292
#68	.031
1/32	.03125
#67	.032
#66	.033
#65	.035
#64	.036
#63	.037
#62	.038
#61	.039
#60	.040
#59	.041
#58	.042
#57	.043
#56	.0465
3/64	.04688	#0-80
#55	.052
#54	.055
#53	.0595	#1-64
#53	.0595	#1-72
1/16	.0625
#52	.0635
#51	.067	#2-56
#50	.070	#2-64
#49	.073
#48	.076
5/64	.07813
#47	.0785	#3-48
#46	.081
#45	.082	#3-56
#44	.086
#43	.089	#4-40
#42	.0935	#4-48
3/32	.09375
#41	.096
#40	.098
#39	.0995
#38	.1015	#5-40
#37	.104	#5-44
#36	.1065	#6-32
7/64	.10938
#35	.110
#34	.111
#33	.113	#6-40
#32	.116
#31	.120

Drill Inch	Decimal	Tap Size
1/8	.125
#30	.1285
#29	.136	#8-32
#29	.136	#8-36
#28	.1405
9/64	.14063
#27	.144
#26	.147
#25	.1495	#10-24
#24	.152
#23	.154
5/32	.15625
#22	.157
#21	.159	#10-32
#20	.161
#19	.166
#18	.1695
11/64	.17188
#17	.173	#12-24
#16	.177
#15	.180	#12-28
#14	.182
#13	.185
3/16	.1875
#12	.189
#11	.191
#10	.1935
#9	.196
#8	.199
#7	.201	1/4-20
13/64	.20313
#6	.204
#5	.2055
#4	.209
#3	.213	1/4-28
7/32	.21875
#2	.221
#1	.228
A	.234
15/64	.23438
B	.238
C	.242
D	.246
1/4	.250
E	.250
F	.257	5/16-18
G	.261
17/64	.26563
H	.266
I	.272	5/16-24
J	.277
K	.281
9/32	.28125
L	.29
M	.295
19/64	.29688
N	.302

Drill Inch	Decimal	Tap Size
5/16	.3125	3/8-16
O	.316
P	.323
21/64	.32813
Q	.332	3/8-24
R	.339
11/32	.34375
S	.348
T	.358	7/16-14
23/64	.35938
U	.368
3/8	.375
V	.377
W	.386
25/64	.39063	7/16-20
X	.397
Y	.404
13/32	.40625
Z	.413
27/64	.42188	1/2-13
7/16	.4375
29/64	.45313	1/2-20
15/32	.46875
31/64	.48438	9/16-12
1/2	.500
33/64	.51563	9/16-18
17/32	.53125	5/8-11
35/64	.54688
9/16	.5625	5/8-18
37/64	.57813
19/32	.59375
39/64	.60938
5/8	.625
41/64	.64063	3/4-10
21/32	.65625
43/64	.67188
11/16	.6875	3/4-16
45/64	.70313
23/32	.71875
47/64	.73438
3/4	.750
49/64	.76563	7/8-9
25/32	.78125
51/64	.79688
13/16	.8125	7/8-14
53/64	.82813
27/32	.84375
55/64	.85938
7/8	.875	1-8
57/64	.89063
29/32	.90625	1-12
59/64	.92188
15/16	.9375
61/64	.95313
31/32	.96875
63/64	.98438	1 1/8-7
1	1.000

Metric Tap Drill Sizes & Decimal Equivalents

Drill mm	Decimal	Tap Size
0.75	.0295	1x0.25
0.85	.0335	1.1x0.25
0.95	.0374	1.2x0.25
1.10	.0433	1.4x0.30
1.25	.0492	1.6x0.35
1.45	.0571	1.8x0.35
1.6	.0630	2x0.40
1.75	.0689	2x0.25
1.75	.0689	2.2x0.45
1.95	.0768	2.2x0.25
2.05	.0807	2.3x0.25
2.05	.0807	2.5x0.45
2.15	.0846	2.5x0.35
2.5	.0984	3x0.50
2.65	.1043	3x0.35
2.9	.1142	3.5x0.6
3.15	.1240	3.5x0.35
3.3	.1299	4x0.7
3.5	.1378	4x0.5
3.6	.1417	4x0.35
3.7	.1457	4.5x0.75
4.2	.1654	5x0.8
4.5	.1772	5x0.5
5	.1969	6x1
5.25	.2067	6x0.75
5.5	.2165	6x0.5
6	.2362	7x1

Drill Inch	Decimal	Tap Size
6.25	.2461	7x0.75
6.8	.2677	8x1.25
7.0	.2756	8x1
7.25	.2854	8x0.75
7.5	.2953	8x0.5
7.8	.3071	9x1.25
8	.3150	9x1
8.2	.3228	9x0.75
8.5	.3346	10x1.5
8.8	.3465	10x1.25
9	.3543	10x1
9.25	.3642	10x0.75
9.5	.3740	10x0.5
9.5	.3740	11x1.5
10	.3937	11x1
10.2	.4016	12x1.75
10.5	.4134	12x1.5
10.8	.4252	12x1.25
11	.4331	12x1
11.25	.4429	12x.75
12	.4724	13x1
12	.4724	14x2
12.5	.4921	14x1.5
12.8	.5039	14x1.25
13	.5118	14x1
13.5	.5315	15x1.5
14	.5512	15x1

Drill mm	Decimal	Tap Size
14	.5512	16x2
14.5	.5709	16x1.5
15	.5906	16x1
15.5	.6102	18x2.5
16	.6299	18x2
16.5	.6496	18x1.5
17	.6693	18x1
17.5	.6890	20x2.5
18	.7087	20x2
18.5	.7283	20x1.5
19	.7480	20x1
19.5	.7677	22x2.5
20	.7874	22x2
20.5	.8071	22x1.5
21	.8268	22x1
21	.8268	24x3
22	.8661	24x2
22.5	.8858	24x1.5
23	.9055	24x1
23.5	.9252	25x1.5
24	.9449	5x1
24	.9449	27x3
24.5	.9646	26x1.5
25	.9843	27x2
25.5	1.0039	27x1.5
26	1.0236	28x2
26.5	1.0433	28x1.5

Pipe Threads

Drill NPT	Drill NPS	Tap Size
D	1/4	1/16-27
R	S	1/8-27
7/16	29/64	1/4-18
37/64	19/32	3/8-18

Drill NPT	Drill NPS	Tap Size
45/64	47/64	1/2-14
59/64	15/16	3/4-14
1 5/32	1 3/16	1-11.5
1 1/2	1 33/64	1.25-11.5

Drill NPT	Drill NPS	Tap Size
1 47/64	1 3/4	1.5-11.5
2 7/32	2 7/32	2-11.5
2 5/8	2 21/32	2.5-8
3 1/4	3 9/32	3-8

Inch Bolt Torque Table
Metric Bolt Torque Table
Torque Wrench Adapter Calculator
Cutting Speeds and Feeds Calculators

Note: Much effort has been made to make sure that this information is accurate. However, it is the user's responsibility to verify that the provided information is correct before using it.