M10 × 1.5 Tap Drill Size & Thread Specs

Everything for a M10 × 1.5 coarse pitch thread on one page: tap drill (8.5 mm), clearance holes, wrench and hex key sizes, and the nearest inch thread.

M10 × 1.5 · tap with
8.5 mm drill
.3346″
8.5 mm · 77% thread
Inch drill
Q · .3320
Clearance
10.5 / 11 mm
Wrench
16 mm
Cap screw key
8 mm

Thread

Nominal size
M10 · .3937″
Pitch
1.5 mm · 16.9 TPI
Series
coarse
fine pitch
M10 × 1.25
fine pitch
M10 × 1.0

Drilling

Tap drill
8.5 mm · .3346
Inch substitute
Q · .3320
Close fit
10.5 mm
Normal fit
11 mm
Free fit
12 mm

Tools

Hex head (ISO 4017)
16 mm
Hex head (DIN 933)
17 mm
Socket head cap key
8 mm
Button head key
6 mm
Flat head key
6 mm

Nearest inch

Thread
3/8-16
Major diameter
.3750″
Threads per inch
16
Tap drill
5/16
Interchangeable
No

Not interchangeable means the threads look close but won't run together: forcing one into the other strips both.

Drill size by thread percentage

Larger drill, less thread, easier tapping. 75% is the usual target.

DrillDecimalmmThread
8.4 mm.33078.482%
Q.33208.4380%
8.5 mm.33468.577%
8.6 mm.33868.672%
R.33908.6171%
8.7 mm.34258.767%
11/32.34388.7365%
8.8 mm.34658.862%
S.34808.8460%
8.9 mm.35048.956%
9 mm.3543951%
T.35809.0947%
9.1 mm.35839.146%
23/64.35949.1345%

Neighboring sizes

Questions

What does M10 × 1.5 mean?
An ISO metric thread with a 10 mm major diameter and a 1.5 mm pitch (the distance from one thread crest to the next). It’s the coarse pitch for M10.
Can I use a Q drill instead?
Usually. Q is .3320″ against .3346″ for the 8.5 mm drill, which changes the thread engagement by a few percent at most.