← All machinist tools · Hole geometry
Countersink depth calculator
Use the screw’s specified included angle, such as 82° or 90°. Depth is measured from the plane at the pilot diameter to the large diameter. Tool tip flats, runout and edge breaks change an actual setup.
Formula and inputs
Axial conical depth = (large diameter − pilot diameter) / (2 tan(included angle / 2)).
Worked example
A 10 mm top diameter over a 5 mm pilot with a 90° included angle has 2.5 mm ideal conical depth.
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.