21/64 inch in mm and decimal

21/64 in = 0.328125 in = 8.334 mm. Closest metric drill: 8.3 mm.

Nearby drill sizes

Drill	Type	Inch	mm	Difference
N	letter	.3020 in	7.671	-26.1 thou
5/16	fraction	.3125 in	7.938	-15.6 thou
O	letter	.3160 in	8.026	-12.1 thou
P	letter	.3230 in	8.204	-5.1 thou
21/64	fraction	.3281 in	8.334	0.0 thou
Q	letter	.3320 in	8.433	3.9 thou
R	letter	.3390 in	8.611	10.9 thou
11/32	fraction	.3438 in	8.731	15.6 thou
S	letter	.3480 in	8.839	19.9 thou

1 thou = 0.001 in = 0.0254 mm. Drills a few thou apart are usually interchangeable for clearance holes, but not for tap drills or reamer pilots.