DrillBitMax

Drill bit size chart

Every standard fractional, number, letter and metric drill size with its decimal inch and millimeter diameter, plus a finder for the nearest size.

Find the nearest drill size

Enter a hole diameter in millimeters or inches. Fractions such as 5/16 work too.

6.000 mm = 0.2362 in

Fractional

15/64 in

5.953 mm, -0.047 mm

Number gauge

#1

5.791 mm, -0.209 mm

Letter

B

6.045 mm, +0.045 mm

Metric

6 mm

6.000 mm, +0.000 mm

Fractional drill sizes

Fractional bits run from 1/64 in to 1 in in 1/64 in steps. Millimeter values are exact conversions.

SizeInchmm
1/64 in.01560.397
1/32 in.03120.794
3/64 in.04691.191
1/16 in.06251.587
5/64 in.07811.984
3/32 in.09382.381
7/64 in.10942.778
1/8 in.12503.175
9/64 in.14063.572
5/32 in.15623.969
11/64 in.17194.366
3/16 in.18754.762
13/64 in.20315.159
7/32 in.21885.556
15/64 in.23445.953
1/4 in.25006.350
17/64 in.26566.747
9/32 in.28127.144
19/64 in.29697.541
5/16 in.31257.938
21/64 in.32818.334
11/32 in.34388.731
23/64 in.35949.128
3/8 in.37509.525
25/64 in.39069.922
13/32 in.406210.319
27/64 in.421910.716
7/16 in.437511.112
29/64 in.453111.509
15/32 in.468811.906
31/64 in.484412.303
1/2 in.500012.700
SizeInchmm
33/64 in.515613.097
17/32 in.531213.494
35/64 in.546913.891
9/16 in.562514.287
37/64 in.578114.684
19/32 in.593815.081
39/64 in.609415.478
5/8 in.625015.875
41/64 in.640616.272
21/32 in.656216.669
43/64 in.671917.066
11/16 in.687517.462
45/64 in.703117.859
23/32 in.718818.256
47/64 in.734418.653
3/4 in.750019.050
49/64 in.765619.447
25/32 in.781219.844
51/64 in.796920.241
13/16 in.812520.637
53/64 in.828121.034
27/32 in.843821.431
55/64 in.859421.828
7/8 in.875022.225
57/64 in.890622.622
29/32 in.906223.019
59/64 in.921923.416
15/16 in.937523.812
61/64 in.953124.209
31/32 in.968824.606
63/64 in.984425.003
1 in1.000025.400

Number drill sizes

Number gauge bits run from #80, the smallest, to #1. The higher the number, the smaller the bit.

SizeInchmm
#80.01350.343
#79.01450.368
#78.01600.406
#77.01800.457
#76.02000.508
#75.02100.533
#74.02250.571
#73.02400.610
#72.02500.635
#71.02600.660
#70.02800.711
#69.02920.742
#68.03100.787
#67.03200.813
#66.03300.838
#65.03500.889
#64.03600.914
#63.03700.940
#62.03800.965
#61.03900.991
#60.04001.016
#59.04101.041
#58.04201.067
#57.04301.092
#56.04651.181
#55.05201.321
#54.05501.397
SizeInchmm
#53.05951.511
#52.06351.613
#51.06701.702
#50.07001.778
#49.07301.854
#48.07601.930
#47.07851.994
#46.08102.057
#45.08202.083
#44.08602.184
#43.08902.261
#42.09352.375
#41.09602.438
#40.09802.489
#39.09952.527
#38.10152.578
#37.10402.642
#36.10652.705
#35.11002.794
#34.11102.819
#33.11302.870
#32.11602.946
#31.12003.048
#30.12853.264
#29.13603.454
#28.14053.569
#27.14403.658
SizeInchmm
#26.14703.734
#25.14953.797
#24.15203.861
#23.15403.912
#22.15703.988
#21.15904.039
#20.16104.089
#19.16604.216
#18.16954.305
#17.17304.394
#16.17704.496
#15.18004.572
#14.18204.623
#13.18504.699
#12.18904.801
#11.19104.851
#10.19354.915
#9.19604.978
#8.19905.055
#7.20105.105
#6.20405.182
#5.20555.220
#4.20905.309
#3.21305.410
#2.22105.613
#1.22805.791

Letter drill sizes

Letter sizes pick up where number sizes stop, from A at 0.234 in to Z at 0.413 in.

SizeInchmm
A.23405.944
B.23806.045
C.24206.147
D.24606.248
E.25006.350
F.25706.528
G.26106.629
H.26606.756
I.27206.909
J.27707.036
K.28107.137
L.29007.366
M.29507.493
SizeInchmm
N.30207.671
O.31608.026
P.32308.204
Q.33208.433
R.33908.611
S.34808.839
T.35809.093
U.36809.347
V.37709.576
W.38609.804
X.397010.084
Y.404010.262
Z.413010.490

Metric drill sizes

Common metric sizes from 1 to 13 mm in 0.5 mm steps, then 14 to 25 mm, with the nearest fractional bit.

SizeInchmmNearest fraction
1 mm.03941.03/64 in
1.5 mm.05911.51/16 in
2 mm.07872.05/64 in
2.5 mm.09842.53/32 in
3 mm.11813.01/8 in
3.5 mm.13783.59/64 in
4 mm.15754.05/32 in
4.5 mm.17724.511/64 in
5 mm.19695.013/64 in
5.5 mm.21655.57/32 in
6 mm.23626.015/64 in
6.5 mm.25596.51/4 in
7 mm.27567.09/32 in
7.5 mm.29537.519/64 in
8 mm.31508.05/16 in
8.5 mm.33468.521/64 in
9 mm.35439.023/64 in
9.5 mm.37409.53/8 in
10 mm.393710.025/64 in
SizeInchmmNearest fraction
10.5 mm.413410.513/32 in
11 mm.433111.07/16 in
11.5 mm.452811.529/64 in
12 mm.472412.015/32 in
12.5 mm.492112.531/64 in
13 mm.511813.033/64 in
14 mm.551214.035/64 in
15 mm.590615.019/32 in
16 mm.629916.05/8 in
17 mm.669317.043/64 in
18 mm.708718.045/64 in
19 mm.748019.03/4 in
20 mm.787420.025/32 in
21 mm.826821.053/64 in
22 mm.866122.055/64 in
23 mm.905523.029/32 in
24 mm.944924.015/16 in
25 mm.984325.063/64 in

Drill size questions

What sizes do fractional drill bits come in?

Jobber-length fractional drill bits run from 1/64 in to 1 in in steps of 1/64 in, as set out in the ANSI B94.11M standard.

What do number and letter drill sizes mean?

Number gauge sizes run from #80, the smallest at 0.0135 in, up to #1 at 0.228 in. Letter sizes continue from A at 0.234 in to Z at 0.413 in. The higher the number, the smaller the bit.

How are metric drill bits sized?

Metric bits are named by their diameter in millimeters. BS 328 lists 230 sizes from 0.2 mm to 25.0 mm, in 0.1 mm steps between 3.0 and 13.9 mm. Sets sold in hardware stores usually go up in 0.5 mm steps.

How do I convert drill sizes between inches and millimeters?

Multiply inches by 25.4 to get millimeters, or divide millimeters by 25.4 to get inches. For example, 1/4 in is 6.35 mm, so the nearest bit in a 0.5 mm-step metric set is 6.5 mm.

Stock drill bit sets in the sizes you sell

We supply HSS twist drill sets and step drills for distributors, in metric or fractional sizes, under your brand.

Request a quoteHSS twist drill sets