Bolt Circle Calculator
Bolt hole positions on a circle from the bolt circle diameter and the number of holes.
Compare Your Options And Get Clear Answers
Bolt hole positions on a circle from the bolt circle diameter and the number of holes.
Bolt Circle Estimator
Enter your numbers below for an instant estimate.
How It Works
Key concepts behind this calculator
Enter Values
Fill in each field with your own numbers.
Calculate
Results update as you change the inputs.
Review
Read the breakdown and the explanation.
Adjust
Change values to compare scenarios.
Bolt Quick Guide
Typical values for reference.
| PCD mm | Holes | First angle | Hole angle |
|---|---|---|---|
| 100 | 3 | 90 | 120.00 deg |
| 100 | 4 | 90 | 90.00 deg |
| 100 | 5 | 90 | 72.00 deg |
| 100 | 8 | 90 | 45.00 deg |
| Rule of Thumb | Check inputs | Use as a guide | Round sensibly |
Bolt Circle Calculator FAQ
Answers to common questions about this calculator.
The circle passing through the centres of the bolt holes.
Measure from one hole edge to the centre of the farthest hole.
Angle = 360 / n; chord = 2 R sin(180 / n).
It is an estimate based on the inputs you enter. Check real quotes, labels or official guidance for important decisions.