Countersink Depth Calculator
Calculate cone depth from the countersink and through-hole diameters. Compare it with sheet thickness before adding a countersink operation to a laser-cut part.
Hole inputs
Countersink result
- Depth from surface
- 0.1438 in
- Remaining thickness
- 0.1062 in
The theoretical cone stops within the entered stock. This geometric check does not approve fastener seating, residual strength, or a minimum web.
Method
Use the major diameter at the top surface, the diameter of the straight through-hole, and the full included cone angle from the drawing or tool specification. The calculation uses the difference between the two radii, not the full major radius. Enter the actual stock thickness to see the theoretical material remaining below the cone. A zero or negative remaining thickness triggers a breakthrough warning.
Depth = (major diameter − through-hole diameter) ÷ [2 × tan(included angle ÷ 2)]. Remaining thickness = stock thickness − depth.
Worked example
A 0.5 in major diameter over a 0.25 in through-hole at an 82° included angle gives a depth of approximately 0.1438 in. In 0.25 in stock, approximately 0.1062 in remains below that depth. The 82° angle is an example input, not a recommendation for every fastener.
Limits
The model is an ideal cone intersecting an ideal cylindrical hole. It excludes tool-tip flats, edge breaks, burrs, countersink chatter, screw-head tolerances, and deformation. Remaining thickness is a geometric difference, not a certified minimum web or connection-strength check. Match the entered angle and diameters to the actual fastener and tooling documentation before releasing production.