M1.6 × 0.35 tap drill size

1.25 mm drill — or 3/64 (0.0469 in) = 90% thread

M1.6 coarse series, 0.35 mm pitch. Tap drill Ø = nominal − pitch = 1.6 − 0.35 = 1.25 mm (≈77% thread, the standard chart value).

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.

Need a different thread percentage? Open the tap drill calculator · Metric tap chart · All calculators