Thread Drill size for tapping standard metric threads Clearance hole
M1 0.75 1.2
M1.2 0.95 1.4
M1.4 1.1 1.6
M1.6 1.5 1.8
M1.8 1.4 2
M2 1.6 2.4
M2.2 1.7 2.8
M2.5 2 2.9
M3 2.5 3.4
M3.5 2.9 3.9
M4 3.3 4.5
M5 4.2 5.5
M6 5 6.6
M8 6.8 9
M10 8.5 11
M12 10.2 13.5
M14 12 15.5
M16 14 17.5
M18 15.5 20
M20 17.5 22
M22 19.5 24
M24 21 26
M27 24 30
M30 26.5 33