M12 × 1.5 tap drill size

10.50 mm drill — or Z (0.4130 in) = 77% thread

M12 fine series, 1.5 mm pitch. Tap drill Ø = nominal − pitch = 12 − 1.5 = 10.50 mm (≈77% thread, the standard chart value).

DrillSizeThread %
10.50 mm0.4134 in77%
Z (inch)0.4130 in / 10.49 mm77%

Rounding to your nearest stock drill moves the thread percentage only a few points. Cut taps only — roll-form taps need a larger hole. Verify before you cut.