Calculate the recommended tap drill diameter from thread major diameter and pitch. Useful for checking metric tapping setups before drilling blind or through holes.
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Request a Proposal →For production tapping, confirm the drill size against the tap maker chart, material, thread class, and whether the hole is blind or through.
For a basic cutting tap estimate, subtract the pitch from the major diameter. For example, M8 x 1.25 uses about 6.75 mm.
Yes. Higher thread percentage increases engagement and torque. Many shop applications use less than 100 percent thread to reduce tap breakage.
No. Form taps usually need a larger drill than cutting taps because they displace material instead of cutting chips.
Use this calculator before drilling a hole for a cutting tap, especially when checking metric threads or comparing thread percentage options.
Continue with closely related tools from the machining calculator library.
Use the calculator freely. If the result points to a tooling or process problem, we can source the exact carbide tooling you need from vetted factories in China. Compare factory-direct pricing.
Before you commit to a spec, it helps to know what the market pays for it. These are real, publicly listed factory prices — not a quotation, and not a guess.
We source the tool families below direct from vetted Chinese factories, matched to the material and tolerance you just worked out. Every batch ships with its material certificate and dimensional record.
ORDERING TAPS? Taps are one of the families where Chinese pricing separates most sharply from Western list. See real MOQ and lead time by tool family.
Tell us the part material, lot size, and target price. We’ll match a verified China factory and return a quotation within 48 hours.