Centerdrill Calculator & Reference

Standard centerdrill sizes with drill depth and point depth calculations. Click any row to populate the calculator inputs.

Standard Centerdrill Sizes

Click a row to load values into the calculator below

Size	Body Dia	Tip Dia	Drill Depth	Point Depth

Custom Calculation

Body Diameter

Tip Diameter

Drill Depth = (Body Dia - Tip Dia) / (2 × tan(30°))
Based on the standard 60° included angle of a centerdrill.

Point Depth = (Tip Dia / 2) / tan(30°)
The depth of the conical point at the tip of the centerdrill.

Why Center Drill Sizing Matters

Center drills create the starting point for lathe work between centers and provide a guide for twist drills in mill work. Using the wrong size means the live center won't seat properly, or your drill will walk off position.

Standard sizes (#1 through #8) each have specific body diameter, point diameter, and drill depth
The 60-degree countersink must match your lathe center — a #3 center drill is the workhorse for most turning jobs
Drill depth matters: too shallow and the center won't support the part, too deep and you waste material or weaken the end

Centerdrill Calculator & Reference

Why Center Drill Sizing Matters

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