threadsizes

Drill size chart

Number, letter and fractional drills in one list, sorted by size, so you can see what sits between two fractions. Number drills run backwards (#80 is the smallest, #1 the largest) and hand over to the letter series at A. The last column links the threads that use that drill as their tap drill.

Inch drillsMetric drillsTap drill chart
Number, letter and fractional drills to 1 inch
DrillInchmmTaps
#80 0.01350.34 mm 0.34
#79 0.01450.37 mm 0.37
1/64" 0.01560.40 mm 0.40
#78 0.01600.41 mm 0.41
#77 0.01800.46 mm 0.46
#76 0.02000.51 mm 0.51
#75 0.02100.53 mm 0.53
#74 0.02250.57 mm 0.57
#73 0.02400.61 mm 0.61
#72 0.02500.64 mm 0.64
#71 0.02600.66 mm 0.66
#70 0.02800.71 mm 0.71
#69 0.02920.74 mm 0.74
#68 0.03100.79 mm 0.79
1/32" 0.03130.79 mm 0.79
#67 0.03200.81 mm 0.81
#66 0.03300.84 mm 0.84
#65 0.03500.89 mm 0.89
#64 0.03600.91 mm 0.91
#63 0.03700.94 mm 0.94
#62 0.03800.97 mm 0.97
#61 0.03900.99 mm 0.99
#60 0.04001.02 mm 1.02
#59 0.04101.04 mm 1.04
#58 0.04201.07 mm 1.07
#57 0.04301.09 mm 1.09
#56 0.04651.18 mm 1.18
3/64" 0.04691.19 mm 1.19
#55 0.05201.32 mm 1.32
#54 0.05501.40 mm 1.40
#53 0.05951.51 mm 1.51
1/16" 0.06251.59 mm 1.59
#52 0.06351.61 mm 1.61
#51 0.06701.70 mm 1.70
#50 0.07001.78 mm 1.78 #2-56
#49 0.07301.85 mm 1.85
#48 0.07601.93 mm 1.93
5/64" 0.07811.99 mm 1.99
#47 0.07851.99 mm 1.99
#46 0.08102.06 mm 2.06
#45 0.08202.08 mm 2.08
#44 0.08602.18 mm 2.18
#43 0.08902.26 mm 2.26 #4-40
#42 0.09352.38 mm 2.38
3/32" 0.09382.38 mm 2.38
#41 0.09602.44 mm 2.44
#40 0.09802.49 mm 2.49
#39 0.09952.53 mm 2.53
#38 0.10152.58 mm 2.58
#37 0.10402.64 mm 2.64
#36 0.10652.71 mm 2.71 #6-32
7/64" 0.10942.78 mm 2.78
#35 0.11002.79 mm 2.79
#34 0.11102.82 mm 2.82
#33 0.11302.87 mm 2.87
#32 0.11602.95 mm 2.95
#31 0.12003.05 mm 3.05
1/8" 0.12503.18 mm 3.18
#30 0.12853.26 mm 3.26
#29 0.13603.45 mm 3.45 #8-32
#28 0.14053.57 mm 3.57
9/64" 0.14063.57 mm 3.57
#27 0.14403.66 mm 3.66
#26 0.14703.73 mm 3.73
#25 0.14953.80 mm 3.80 #10-24
#24 0.15203.86 mm 3.86
#23 0.15403.91 mm 3.91
5/32" 0.15633.97 mm 3.97
#22 0.15703.99 mm 3.99
#21 0.15904.04 mm 4.04 #10-32
#20 0.16104.09 mm 4.09
#19 0.16604.22 mm 4.22
#18 0.16954.31 mm 4.31
11/64" 0.17194.37 mm 4.37
#17 0.17304.39 mm 4.39
#16 0.17704.50 mm 4.50 #12-24
#15 0.18004.57 mm 4.57
#14 0.18204.62 mm 4.62
#13 0.18504.70 mm 4.70
3/16" 0.18754.76 mm 4.76
#12 0.18904.80 mm 4.80
#11 0.19104.85 mm 4.85
#10 0.19354.92 mm 4.92
#9 0.19604.98 mm 4.98
#8 0.19905.06 mm 5.06
#7 0.20105.11 mm 5.11 1/4-20
13/64" 0.20315.16 mm 5.16
#6 0.20405.18 mm 5.18
#5 0.20555.22 mm 5.22
#4 0.20905.31 mm 5.31
#3 0.21305.41 mm 5.41 1/4-28
7/32" 0.21885.56 mm 5.56
#2 0.22105.61 mm 5.61
#1 0.22805.79 mm 5.79
A 0.23405.94 mm 5.94
15/64" 0.23445.95 mm 5.95
B 0.23806.05 mm 6.05
C 0.24206.15 mm 6.15
D 0.24606.25 mm 6.25
1/4" 0.25006.35 mm 6.35
E 0.25006.35 mm 6.35
F 0.25706.53 mm 6.53 5/16-18
G 0.26106.63 mm 6.63
17/64" 0.26566.75 mm 6.75
H 0.26606.76 mm 6.76
I 0.27206.91 mm 6.91 5/16-24
J 0.27707.04 mm 7.04
K 0.28107.14 mm 7.14
9/32" 0.28137.14 mm 7.14
L 0.29007.37 mm 7.37
M 0.29507.49 mm 7.49
19/64" 0.29697.54 mm 7.54
N 0.30207.67 mm 7.67
5/16" 0.31257.94 mm 7.94 3/8-16
O 0.31608.03 mm 8.03
P 0.32308.20 mm 8.20
21/64" 0.32818.34 mm 8.34
Q 0.33208.43 mm 8.43 3/8-24
R 0.33908.61 mm 8.61 1/8 NPT
11/32" 0.34388.73 mm 8.73
S 0.34808.84 mm 8.84
T 0.35809.09 mm 9.09
23/64" 0.35949.13 mm 9.13
U 0.36809.35 mm 9.35 7/16-14
3/8" 0.37509.53 mm 9.53
V 0.37709.58 mm 9.58
W 0.38609.80 mm 9.80
25/64" 0.39069.92 mm 9.92 7/16-20
X 0.397010.08 mm 10.08
Y 0.404010.26 mm 10.26
13/32" 0.406310.32 mm 10.32
Z 0.413010.49 mm 10.49
27/64" 0.421910.72 mm 10.72 1/2-13
7/16" 0.437511.11 mm 11.11 1/4 NPT
29/64" 0.453111.51 mm 11.51 1/2-20
15/32" 0.468811.91 mm 11.91
31/64" 0.484412.30 mm 12.30
1/2" 0.500012.70 mm 12.70
33/64" 0.515613.10 mm 13.10
17/32" 0.531313.49 mm 13.49 5/8-11
35/64" 0.546913.89 mm 13.89
9/16" 0.562514.29 mm 14.29
37/64" 0.578114.69 mm 14.69 5/8-18, 3/8 NPT
19/32" 0.593815.08 mm 15.08
39/64" 0.609415.48 mm 15.48
5/8" 0.625015.88 mm 15.88
41/64" 0.640616.27 mm 16.27
21/32" 0.656316.67 mm 16.67 3/4-10
43/64" 0.671917.07 mm 17.07
11/16" 0.687517.46 mm 17.46 3/4-16
45/64" 0.703117.86 mm 17.86
23/32" 0.718818.26 mm 18.26 1/2 NPT
47/64" 0.734418.65 mm 18.65
3/4" 0.750019.05 mm 19.05
49/64" 0.765619.45 mm 19.45
25/32" 0.781319.84 mm 19.84
51/64" 0.796920.24 mm 20.24
13/16" 0.812520.64 mm 20.64
53/64" 0.828121.04 mm 21.04
27/32" 0.843821.43 mm 21.43
55/64" 0.859421.83 mm 21.83
7/8" 0.875022.23 mm 22.23
57/64" 0.890622.62 mm 22.62
29/32" 0.906323.02 mm 23.02
59/64" 0.921923.42 mm 23.42 3/4 NPT
15/16" 0.937523.81 mm 23.81
61/64" 0.953124.21 mm 24.21
31/32" 0.968824.61 mm 24.61
63/64" 0.984425.00 mm 25.00
1" 1.000025.40 mm 25.40
Metric drills 1 to 13 mm
DrillInchTaps
1 mm 0.0394
1.1 mm 0.0433
1.2 mm 0.0472
1.3 mm 0.0512
1.4 mm 0.0551
1.5 mm 0.0591
1.6 mm 0.0630 M2 x 0.4
1.7 mm 0.0669
1.8 mm 0.0709
1.9 mm 0.0748
2 mm 0.0787
2.1 mm 0.0827
2.2 mm 0.0866
2.3 mm 0.0906
2.4 mm 0.0945
2.5 mm 0.0984 M3 x 0.5
2.6 mm 0.1024
2.7 mm 0.1063
2.8 mm 0.1102
2.9 mm 0.1142
3 mm 0.1181
3.1 mm 0.1221
3.2 mm 0.1260
3.3 mm 0.1299 M4 x 0.7
3.4 mm 0.1339
3.5 mm 0.1378
3.6 mm 0.1417
3.7 mm 0.1457
3.8 mm 0.1496
3.9 mm 0.1535
4 mm 0.1575
4.1 mm 0.1614
4.2 mm 0.1654 M5 x 0.8
4.3 mm 0.1693
4.4 mm 0.1732
4.5 mm 0.1772
4.6 mm 0.1811
4.7 mm 0.1850
4.8 mm 0.1890
4.9 mm 0.1929
5 mm 0.1969 M6 x 1
5.1 mm 0.2008
5.2 mm 0.2047
5.3 mm 0.2087
5.4 mm 0.2126
5.5 mm 0.2165
5.6 mm 0.2205
5.7 mm 0.2244
5.8 mm 0.2284
5.9 mm 0.2323
6 mm 0.2362
6.1 mm 0.2402
6.2 mm 0.2441
6.3 mm 0.2480
6.4 mm 0.2520
6.5 mm 0.2559
6.6 mm 0.2598
6.7 mm 0.2638
6.8 mm 0.2677 M8 x 1.25
6.9 mm 0.2717
7 mm 0.2756 M8 x 1
7.1 mm 0.2795
7.2 mm 0.2835
7.3 mm 0.2874
7.4 mm 0.2913
7.5 mm 0.2953
7.6 mm 0.2992
7.7 mm 0.3032
7.8 mm 0.3071
7.9 mm 0.3110
8 mm 0.3150
8.1 mm 0.3189
8.2 mm 0.3228
8.3 mm 0.3268
8.4 mm 0.3307
8.5 mm 0.3347 M10 x 1.5
8.6 mm 0.3386
8.7 mm 0.3425
8.8 mm 0.3465 M10 x 1.25
8.9 mm 0.3504
9 mm 0.3543 M10 x 1
9.1 mm 0.3583
9.2 mm 0.3622
9.3 mm 0.3661
9.4 mm 0.3701
9.5 mm 0.3740
9.6 mm 0.3780
9.7 mm 0.3819
9.8 mm 0.3858
9.9 mm 0.3898
10 mm 0.3937
10.1 mm 0.3976
10.2 mm 0.4016 M12 x 1.75
10.3 mm 0.4055
10.4 mm 0.4095
10.5 mm 0.4134 M12 x 1.5
10.6 mm 0.4173
10.7 mm 0.4213
10.8 mm 0.4252
10.9 mm 0.4291
11 mm 0.4331
11.1 mm 0.4370
11.2 mm 0.4409
11.3 mm 0.4449
11.4 mm 0.4488
11.5 mm 0.4528
11.6 mm 0.4567
11.7 mm 0.4606
11.8 mm 0.4646
11.9 mm 0.4685
12 mm 0.4724
12.1 mm 0.4764
12.2 mm 0.4803
12.3 mm 0.4843
12.4 mm 0.4882
12.5 mm 0.4921
12.6 mm 0.4961
12.7 mm 0.5000
12.8 mm 0.5039
12.9 mm 0.5079
13 mm 0.5118

Number and letter drill diameters per ASME B94.11M, checked against published drill charts. Sources on How we calculate.