Countersink Depth Calculator

Your details

82 deg is the ANSI standard for inch flat-head screws; 90 deg is the ISO standard for metric flat-head screws; 118 deg matches a standard twist-drill tip angle for spot-drilling.
The diameter of the countersink opening at the workpiece surface.
mm
Sharp-point: the bit tapers to a perfect point. Truncated: the tip is flat or has a pilot drill - enter the tip diameter and clearance below.
If you enter the screw shank diameter the calculator will also show the minimum head-flush depth and excess depth (how much the screw head sits below the surface).
mm
Countersink depth
5

Depth to plunge the bit from the workpiece surface

Depth unitmm
Surface diameter (solved)10
Diameter unitmm
Half-angle45deg
Depth-to-diameter ratio0.5
Flush depth unitmm
Excess depth unitmm

Countersink depth: 5.000 mm

  • Plunge the bit 5.000 mm from the workpiece surface to produce a 10.000 mm opening at the surface.
  • At 90 deg the depth-to-diameter ratio is 0.5000: multiply any surface diameter by this number to get the required depth.

Next stepDrill the clearance or pilot hole first, then run the 90 deg countersink bit to the calculated depth.

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