Bolt Pattern & PCD Calculator

Bolt Pattern & PCD Calculator lays out hole coordinates for any bolt circle, backs out pitch circle diameter from a stud measurement, and puts ANSI B16.5 flange bolting data in your pocket - for machinists, mechanics, wheel fitment, and pipefitters.

No internet. No account. Everything runs on the device.

BOLT CIRCLE
- Enter hole count (2-36), bolt circle diameter, and a start angle
- Get X/Y coordinates for every hole, measured from center
- Angular spacing and chord distance between adjacent holes
- Copy the table to your clipboard or share it as a CSV coordinate sheet

WHEEL PCD FINDER
- Enter bolt count (4/5/6/8) and the measured center-to-center distance between two adjacent studs
- Back out the pitch circle diameter
- Dual-pattern hint (metric to inch) when there's a clean equivalent
- Reference table of common wheel bolt patterns with example vehicle makes

FLANGE BOLTS
- ANSI B16.5 reference for nominal pipe sizes 1/2" through 12"
- Class 150 and Class 300 bolt count, bolt size, and bolt circle diameter side by side
- Full reference table for every size

CONVERT
- Millimeter/inch converter in both directions
- Fraction output rounded to the nearest 1/16"
- Common bolt-pattern equivalents at a glance

Reference values (wheel patterns, ANSI B16.5 flange data) are commonly-published figures meant as a practical starting point - always confirm against the actual part, hub, or flange spec before ordering, fabricating, or bolting up.

This app is ad-supported. Sharing a coordinate sheet as CSV may show a short video ad; if no ad is available your coordinate sheet still shares.