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Calculate countersink depth or radial width from the cutter's included angle. Check diameter increase with a 90° worked example.
Countersink
1What do you want to calculate?
2Enter the measurements
Full tool angle (typically 90° for a chamfer cutter or countersink). Half-angle = half this value.
3Result
Click a dimension to copy it
A conical cutter changes chamfer width as penetration changes. Enter its full included angle and choose whether radial width or Z depth is known. The calculator uses half that angle to relate both measurements for an ideal cone.
Known measurements
Included angle = 90° · radial width = 1 mm
Result
Geometric Z depth = 1 mm · diameter increase = 2 mm
On an 8 mm hole, a 1 mm radial width gives a 10 mm mouth. Machine Z also depends on the zero reference and actual cutter tip.
A 90° countersink has a 45° half-angle β. The relationship is Z = radial width / tan β. At 90° included angle, radial width and Z have equal numerical values; other angles differ. Entering 45° as the full angle would produce a different depth.
For a hole diameter d and mouth diameter D, radial width is (D − d)/2. The output 2 × width is the diameter increase, not the final mouth diameter of an existing hole. For an ideal full-tip cone, 2 × width is the cone diameter at that depth.
The geometric calculation excludes a tip flat, corner radius, wear and measured tool zero. Establish the Z reference before transferring the result to the control. Checking the mouth diameter helps adjust the actual tool position without mistaking that offset for a cone-angle change.
Enter the full 90°. The calculator halves it to obtain the 45° half-angle.
Subtract hole diameter from mouth diameter and divide by two. From 8 to 10 mm: (10 − 8)/2 = 1 mm.
First establish tool length reference, tip geometry and work zero. The output is a geometric relationship, not a complete machine position.
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