Construction

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Countersink Depth Calculator.

Calculate countersink depth from diameters and included angle.

On-device calculationNo signup
01

Set your values

Results update as you type.

Depth: 2

Depth

2.000
includedAngleDegrees: 90

includedAngleDegrees

90.000
radialDifference: 2

radialDifference

2.000

Use Cases

Machining and Fabrication

Determine the depth needed to countersink a hole for a flat-head screw or rivet to sit flush with the surface.

Example: For a head diameter of 10 mm, hole diameter of 5 mm, and 90° angle, depth is 2.5 mm.

Quality Control and Inspection

Verify that machined countersinks meet specifications by calculating the expected depth from measured diameters and angle.

Example: Check if a countersink depth of 3 mm matches the required dimensions.

Frequently Asked Questions

How do I calculate countersink depth?
Enter the head diameter, hole diameter, and included angle. The calculator uses the formula: depth = (head diameter - hole diameter) / (2 * tan(included angle / 2)).
What is the included angle in a countersink?
The included angle is the total angle at the tip of the countersink tool, typically 82°, 90°, or 100°. It is the angle between the two opposite sides of the conical cut.
Can I use this calculator for any material?
Yes, the calculation is geometric and independent of material. However, actual machining may require adjustments for material hardness or tool wear.

Tips & Common Mistakes

Tips

  • Ensure all measurements are in millimeters and the angle in degrees for accurate results.
  • Use the actual measured head diameter of the fastener, not the nominal size, for precision.
  • For standard countersinks, common included angles are 82°, 90°, and 100°; verify the correct one.
  • Double-check your input values, as small errors in diameter or angle can significantly affect depth.

Common Mistakes to Avoid

  • Using the screw head diameter instead of the countersink head diameter (the larger top diameter).
  • Entering the angle in radians instead of degrees, leading to incorrect depth.
  • Forgetting to divide the difference in diameters by 2, which doubles the calculated depth.

Last updated: August 13, 2026