Countersink Depth Calculator

What Is a Countersink Depth Calculator?

A countersink depth calculator determines how deep to drill a conical hole so a screw or bolt head sits flush with or below the workpiece surface. Enter the countersink diameter at the surface and the cone angle, and the tool returns the required depth instantly. This is essential for woodworking, sheet metal, and assembly work where raised fastener heads would interfere with fit or finish.

Countersink Depth Formula

The depth of a countersunk hole depends on the opening diameter and the included angle of the cone:

$$ \text{depth} = \frac{\text{diameter} / 2}{\tan(\text{angle} / 2)} $$

Where diameter is the opening width at the surface and angle is the countersink cone angle in degrees. Common angles include 82° for standard wood screws, 90° for general purpose work, and 60° for metric fasteners. The result uses the same length unit as the diameter you enter.

How to Use This Calculator

1. Measure or specify the countersink diameter at the material surface.
2. Select the diameter unit (mm, cm, m, inches, or feet).
3. Choose a standard countersink angle or enter a custom angle.
4. Read the depth result and step-by-step breakdown on the right.

For related fastener layout, try our Bolt Circle Calculator or Clearance Hole Calculator.