M10 × 1 tap drill size

9.00 mm drill — or T (0.3580 in) = 70% thread

M10 fine series, 1 mm pitch. Tap drill Ø = nominal − pitch = 10 − 1 = 9.00 mm (≈77% thread, the standard chart value).

DrillSizeThread %
9.00 mm0.3543 in77%
T (inch)0.3580 in / 9.09 mm70%

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.