Tap Feed Calculator

Why tapping feed isn't a "pick a chip load" decision

A tap's flutes are cut to exactly match the thread pitch it's forming, so the tap must advance exactly one pitch (or 1÷TPI, for imperial) per spindle revolution — not more, not less — or it tears the thread it's cutting instead of following it cleanly. Feed rate = RPM × pitch is a rigid mechanical relationship, not a range to dial in like a milling chip load.

Rigid tapping vs. a tension/compression tap holder

A rigid tapping cycle (G84 with rigid tapping enabled) relies on the machine's own spindle-to-Z synchronization to hit this feed exactly, so the number this calculator gives you is exactly what the control needs programmed. A floating tap holder (self-reversing or tension/compression) tolerates some feed mismatch by letting the tap float slightly, which is a reasonable safety net on an older machine without confirmed rigid tapping, but the tool still wants a feed rate this close to correct even then.

Metric and imperial use the same relationship

Metric threads specify pitch directly in mm per revolution, so feed rate = RPM × pitch (mm) needs no unit conversion beyond keeping the units consistent. Imperial threads specify threads per inch instead of pitch directly, so pitch = 1 ÷ TPI inches per revolution, and the same RPM × pitch relationship applies from there.