Nut size vs Spanner Size


I am doing quite a bit of maintenance at the moment (more on that in future posts).

I had to replace a couple of bolts that were badly damaged but didn’t know the size.  All I had was the spanner/socket size.  Here is a list of spanner/socket size vs bolt size which came in very handy.

Bolt Size Socket/Spanner Size
M3 5.5mm
M4 7mm
M5 8mm
M6 10mm
M7 11mm
M8 13mm
M10 17mm
M12 19mm
M14 22mm
M16 24mm
M18 27mm
M20 30mm
M22 32mm
M24 36mm