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.