Countersink Depth Calculator
Use this countersink depth calculator to estimate the depth of a countersunk hole. It follows the Omni formula that relates countersink diameter to the included countersink angle. That gives you a quick machining check before you set the tool or verify a drawing dimension.
Result
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Quick Answer:
Countersink depth is found from the hole diameter and the included angle using depth = (diameter / 2) / tan(angle / 2). As the included angle grows, the required depth for the same diameter becomes shallower.
What This Countersink Depth Calculator Helps You Do
Use this countersink depth calculator to estimate the depth of a countersunk hole. It follows the Omni formula that relates countersink diameter to the included countersink angle. That gives you a quick machining check before you set the tool or verify a drawing dimension.
How to Calculate Countersink Depth Calculator
- Enter the countersink diameter - Use the target opening diameter of the countersink.
- Enter the included angle - Use the full included angle of the countersink tool or drawing callout.
- Calculate the depth - The calculator applies the trigonometric relation between radius, angle, and depth.
- Compare with the drawing - Use the result to check whether the specified countersink can fit within the available material thickness.
Countersink Depth Calculator Formula
depth = (diameter / 2) / tan(angle / 2)
| Symbol | Definition | Unit |
|---|---|---|
| diameter | Countersink diameter | length |
| angle | Included countersink angle | degrees |
| depth | Countersink depth | length |
Worked Examples
Machining - Standard countersink check
- Diameter: 12 mm
- Angle: 90 degrees
Result: Depth is based on the half-angle trigonometric relation
A steeper included angle produces a shallower countersink for the same diameter.
How to Interpret Your Results
| Range | Meaning | Action |
|---|---|---|
| Smaller angle | Sharper countersink | Expect a deeper cut for the same target diameter. |
| Larger angle | Flatter countersink | Expect a shallower depth for the same target diameter. |
| Larger diameter | More radial opening | Depth increases unless the included angle changes as well. |
Frequently Asked Questions
Use depth = (diameter / 2) / tan(angle / 2), where the angle is the included countersink angle.
The countersink forms two equal right triangles from the centerline, so the trigonometry uses half of the full included angle.
For the same diameter, yes. A larger included angle spreads the countersink wider, which reduces the required depth.
Disclaimer: This is a geometric estimate only. Final machining should consider tool geometry, tolerances, and the exact fastener or drawing standard being used.
Sources
Last reviewed: March 14, 2026