Standard Letter Drill Sizes
Letter size Fractional Decimal Metric
size(inches) Equivalent Equivalent
(in inches) mm
A 15/64 0.234
B 0.238 6.00
C 0.242 6.10
D 0.246 6.20
E 1/4 0.250
F 0.257 6.50
G 0.261 6.60
H 13/64 0.266
I 0.272 6.90
J 0.277 7.00
K 9/32 0.281
L 0.290 7.40
M 0.295 7.50
N 0.302 7.70
O 0.316 8.00
P 0.323 8.20
Q 0.332 8.40
R 0.339 8.60
S 0.348 8.80
T 0.358 9.10
U 0.368 9.30
V 3/8 0.375
W 0.386 9.80
X 0.397 10.10
Y 0.404 10.30
Z 0.413 10.50