Countersink Depth & Diameter Solver

How to use it: select the unknown dimension, then enter the other three. The section view keeps pilot diameter, major diameter, included angle and axial depth visible together.

Formula. Depth = (major - pilot) / (2 x tan(angle / 2)). The solver rearranges this same right-triangle relationship for any selected variable.

Example. A 10 mm major diameter over a 5 mm pilot at 90 degrees needs 2.5 mm axial depth.

The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Solve for

Depth

Pilot diameter

5 mm

Major diameter

10 mm

Included angle

90 deg

Axial depth

2.5 mm

Primary result: Depth: 2.500 mm.

• Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
• Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
• When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.

This is ideal conical geometry. Tool runout, tip flats, chatter, measurement method and fastener tolerances affect the real cut. Verify critical work with the actual tool and part specification.