Cost, Tolerances & Reference

Bolt Circle Calculator for Hole Coordinates

Generate X/Y coordinates for equally spaced holes on a bolt circle. Useful for CNC milling, drilling layouts, manual layout checks, and bolt pattern programming.

Input Parameters

Results

Hole Coordinate List
Chord Length (mm)
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Bolt Circle formula and how to use it

Set your datum and start angle before programming. Verify whether the drawing uses diameter, radius, or existing hole coordinates.

Frequently asked questions

What is a bolt circle?

A bolt circle is a circular pattern of equally spaced holes around a center point, usually defined by diameter and hole count.

How are bolt circle coordinates calculated?

Each hole is placed at a fixed angle increment. The X and Y values come from cosine and sine of each angle.

Can I use these coordinates directly in G-code?

Yes, if your work offset, units, start angle, and center point match the setup. Always verify the first part.

How to use this Bolt Circle calculator

Use this calculator to generate equally spaced hole coordinates around a center point for CNC drilling or milling.

Common mistakes to avoid

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Need carbide tooling for this operation?

Use the calculator freely. If the result points to a tooling or process problem, we can source the exact carbide tooling you need from vetted factories in China. Compare factory-direct pricing.