31/64 inch in mm and decimal

31/64 in = 0.484375 in = 12.303 mm. Closest metric drill: 12.3 mm.

Taps that use a 31/64 drill

Drill	Type	Inch	mm	Difference
27/64	fraction	.4219 in	10.716	-62.5 thou
7/16	fraction	.4375 in	11.112	-46.9 thou
29/64	fraction	.4531 in	11.509	-31.3 thou
15/32	fraction	.4688 in	11.906	-15.6 thou
31/64	fraction	.4844 in	12.303	0.0 thou
1/2	fraction	.5000 in	12.700	15.6 thou
33/64	fraction	.5156 in	13.097	31.3 thou
17/32	fraction	.5313 in	13.494	46.9 thou
35/64	fraction	.5469 in	13.891	62.5 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.