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Cutting tap drill estimate calculator
This is a quick estimate for ordinary cutting taps. It is not a forming-tap chart or a tolerance-controlled hole specification. Choose the final drill from the tap maker’s table for the thread, material, engagement and tolerance.
Formula and inputs
Approximate cutting-tap drill diameter = major diameter − pitch.
Worked example
M10 × 1.5 gives an 8.5 mm estimate. Confirm the actual recommended drill and hole tolerance before machining.
Use the result in your setup
Confirm the input dimensions and unit system against your drawing before calculating. Keep full precision during a calculation and round only the final value to suit the measurement or programming requirement. A numerical result does not account for a machine’s complete setup, workholding or control configuration.