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Inch – mm converter and drill sizes

Enter a size in mm or inches (fractions such as 5/32 or 1-1/8 work) to convert it and find the nearest drill.

Millimetres
8.500 mm
Inches (decimal)
0.3346 in
Nearest fraction (1/64)
21/64" = 0.3281 in (8.334 mm, -0.166 mm)
Nearest number drill
–
Nearest letter drill
Q = 0.3320 in (8.433 mm, -0.067 mm)

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  • 1 inch = 25.4 mm. Number and letter drills are inch (ANSI) sizes.

Number drill sizes (#1–#80)

Sizeinchmm
#10.22805.791
#20.22105.613
#30.21305.410
#40.20905.309
#50.20555.220
#60.20405.182
#70.20105.105
#80.19905.055
#90.19604.978
#100.19354.915
#110.19104.851
#120.18904.801
#130.18504.699
#140.18204.623
#150.18004.572
#160.17704.496
#170.17304.394
#180.16954.305
#190.16604.216
#200.16104.089
#210.15904.039
#220.15703.988
#230.15403.912
#240.15203.861
#250.14953.797
#260.14703.734
#270.14403.658
#280.14053.569
#290.13603.454
#300.12853.264
#310.12003.048
#320.11602.946
#330.11302.870
#340.11102.819
#350.11002.794
#360.10652.705
#370.10402.642
#380.10152.578
#390.09952.527
#400.09802.489
#410.09602.438
#420.09352.375
#430.08902.261
#440.08602.184
#450.08202.083
#460.08102.057
#470.07851.994
#480.07601.930
#490.07301.854
#500.07001.778
#510.06701.702
#520.06351.613
#530.05951.511
#540.05501.397
#550.05201.321
#560.04651.181
#570.04301.092
#580.04201.067
#590.04101.041
#600.04001.016
#610.03900.991
#620.03800.965
#630.03700.940
#640.03600.914
#650.03500.889
#660.03300.838
#670.03200.813
#680.03100.787
#690.02920.742
#700.02800.711
#710.02600.660
#720.02500.635
#730.02400.610
#740.02250.571
#750.02100.533
#760.02000.508
#770.01800.457
#780.01600.406
#790.01450.368
#800.01350.343

Letter drill sizes (A–Z)

Sizeinchmm
A0.23405.944
B0.23806.045
C0.24206.147
D0.24606.248
E0.25006.350
F0.25706.528
G0.26106.629
H0.26606.756
I0.27206.909
J0.27707.036
K0.28107.137
L0.29007.366
M0.29507.493
N0.30207.671
O0.31608.026
P0.32308.204
Q0.33208.433
R0.33908.611
S0.34808.839
T0.35809.093
U0.36809.347
V0.37709.576
W0.38609.804
X0.397010.084
Y0.404010.262
Z0.413010.490

Fractional drill sizes (1/64–1 inch)

Sizeinchmm
1/64"0.01560.397
1/32"0.03120.794
3/64"0.04691.191
1/16"0.06251.587
5/64"0.07811.984
3/32"0.09382.381
7/64"0.10942.778
1/8"0.12503.175
9/64"0.14063.572
5/32"0.15623.969
11/64"0.17194.366
3/16"0.18754.762
13/64"0.20315.159
7/32"0.21885.556
15/64"0.23445.953
1/4"0.25006.350
17/64"0.26566.747
9/32"0.28127.144
19/64"0.29697.541
5/16"0.31257.938
21/64"0.32818.334
11/32"0.34388.731
23/64"0.35949.128
3/8"0.37509.525
25/64"0.39069.922
13/32"0.406210.319
27/64"0.421910.716
7/16"0.437511.112
29/64"0.453111.509
15/32"0.468811.906
31/64"0.484412.303
1/2"0.500012.700
33/64"0.515613.097
17/32"0.531213.494
35/64"0.546913.891
9/16"0.562514.287
37/64"0.578114.684
19/32"0.593815.081
39/64"0.609415.478
5/8"0.625015.875
41/64"0.640616.272
21/32"0.656216.669
43/64"0.671917.066
11/16"0.687517.462
45/64"0.703117.859
23/32"0.718818.256
47/64"0.734418.653
3/4"0.750019.050
49/64"0.765619.447
25/32"0.781219.844
51/64"0.796920.241
13/16"0.812520.637
53/64"0.828121.034
27/32"0.843821.431
55/64"0.859421.828
7/8"0.875022.225
57/64"0.890622.622
29/32"0.906223.019
59/64"0.921923.416
15/16"0.937523.812
61/64"0.953124.209
31/32"0.968824.606
63/64"0.984425.003
1"1.000025.400
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