Countersink & Drill Point Calculator

Calculate drill point depth and countersink depth for common included angles. Enter hole diameter and optionally a countersink diameter.

Angle Presets

Hole Diameter

Included Angle (°)

Countersink Diameter (optional)

Drill Point Depth: (D / 2) / tan(Angle / 2)
The depth of the conical point formed by the drill tip.

Countersink Depth: ((Csink Dia - Hole Dia) / 2) / tan(Angle / 2)
The additional depth needed to countersink from the hole diameter to the countersink diameter at the given included angle.

Why Countersink Depth Matters

Countersinks let flat head screws sit flush with the surface. The depth depends on the screw head diameter and the countersink angle — typically 82 or 90 degrees in inch, 90 degrees in metric. Getting it wrong means the head sits proud or sinks below flush.

82-degree countersinks are the US standard (ANSI); 90-degree is common for metric flat heads and aerospace fasteners
Depth = (head diameter - hole diameter) / (2 x tan(angle/2)) — this calculator does the trig for you
Always countersink slightly deeper than flush to account for burrs and ensure the head seats fully

Countersink & Drill Point Calculator

Why Countersink Depth Matters

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