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Bolt circle calculator

Work out a bolt-hole pattern and export it as a DXF or SVG. Free and online.

Bolt circle (PCD) calculator

A bolt circle, or pitch circle diameter (PCD), is a set of holes spaced evenly around a centre, the pattern you find on flanges, hubs, adaptor plates and wheel centres. This calculator lays the pattern out for you: set the outer diameter, the bolt circle diameter, the number of holes and the hole size, and the shape updates live. When it looks right, download it as a DXF or SVG, or nest it on a sheet to cut.

Everything runs online on your device, with no sign-up and nothing uploaded. The output carries true circles, so the holes stay round on the machine rather than being cut as many-sided approximations.

How to use it

  1. Enter the outer diameter and the bolt circle diameter (PCD).
  2. Set the number of holes and the hole diameter.
  3. Download the pattern as a DXF or SVG, or nest it on a sheet.

Common questions

What is PCD (pitch circle diameter)?

PCD is the diameter of the imaginary circle that passes through the centre of every bolt hole. It is the standard way to describe a bolt pattern, together with the number of holes.

How do I measure a bolt circle?

For an even number of holes, measure centre to centre across opposite holes. For an odd number, measure from the centre of one hole to the middle of the space between the two opposite holes, then double the distance from the centre of a hole to the middle of the pattern.

Can I export the pattern to cut it?

Yes. Download it as a DXF or SVG for your cutter, or send it straight into NestMaxx to place it on a sheet with your other parts.

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