Look here for metric thread size M4 to M18 + spanner + pitch information

Tap Size mm .	Drill Size mm.
2.3 2.6 3.0 3.5 4.0 4.5 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0	1.9 2.1 2.5 2.9 3.3 3.8 4.2 5.0 6.0 6.8 7.9 8.5 9.5 10.2
Tap Size mm .	Drill Size mm.

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