## Bolt Circle Calculator v1.00

Measure
Number of Bolts
Enter the Number of Bolts on your wheel or axle. Then the Measurement between an adjacent pair of lugs. You can either measure lugs Center To Center or Back To Back. If you measure Back To Back you will then need to know the Bolt Diameter. Works for Metric (mm) as well as Imperial (inch), just enter numbers.

The Common Sizing is a best guess if your measurements are a bit off.

Press CALCULATE to find other values. Hit RESET  to clear the form and SAMPLE if you want to see a sample calculation.
Bolt Circle Diameter
Measure Type
Bolt Diameter
Common Sizing

# Bolt Circle Calculator

Their are a few ways to find the bolt circle for getting the correct rim, axles, and sorted stuff. If you have a tape
measure you can get it pretty quickly and easily using either the 5 Bolt Circle measuring method or the Even
Number Bolt measuring method. With a ruler you can figure out what your bolt circle is.

So why this calculator? Well no other reason then it might be another fun one to add. I had found the formula
online and implemented it. Here's it is for inquiring minds (or incase it's wrong!)

To Find the Bolt Circle from measuring adjacent studs use this formula:

Bolt Circle = BDist / sin(180/n)

Where-
Bolt Circle = The Diameter of the bolt pattern
BDist = The distance CENTER TO CENTER of adjacent lugs
n = Number of bolts in the pattern

Note : The sine function sin(), in this case must expect the value of

The calculator below accepts a few parameters and has the option to allow you to measure from lugs centers or
lugs back to back (as you might do with a caliper). This will work with Metric (mm) or Imperial (inches), or
Parsecs for that matter.

If you want one of the slick looking tools to make the measuring easier just check out Amazon, they have a few
and they are pretty Inexpensive Here are the links (opens in a new window as to not lose your place here)  -

Bolt Pattern Pro

Topline Bolt Caliper

Jegs Varient of the Bolt Caliper (Likely same as Topline)