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Bolt Pattern Calculator

Calculate bolt spacing from bolt circle diameter and lug count.

Introduction

Bolt Pattern Calculator — Calculate bolt spacing from bolt circle diameter and lug count. Enter Bolt circle diameter (mm), Number of lugs to get an instant, accurate result.

Formula

Bolt spacing (mm) = bolt circle diameter (BCD) × sin(180°/lug count), using the standard trigonometric constants for common lug patterns (4-lug: 0.7071, 5-lug: 0.58779, 6-lug: 0.5).

Step-by-step

  1. Enter the Bolt circle diameter (mm).
  2. Enter the Number of lugs.
  3. Click Calculate to see your result instantly.

Real-world example

Example: With Bolt circle diameter (mm) = 114.3, Number of lugs = 5, the Bolt Pattern Calculator gives Bcd In: 4.5, Bolt Spacing Mm: 67.1839, Bolt Spacing In: 2.645.

Frequently Asked Questions

What does a bolt pattern like 5x114.3 mean?
5 is the number of lug bolts, and 114.3 is the bolt circle diameter (BCD) in mm — the diameter of the imaginary circle passing through all the lug bolt centers.
Why is 5-lug spacing measured differently than 4- or 6-lug?
With an odd number of bolts (5), no two bolts sit directly opposite each other, so the spacing between adjacent bolts is calculated using trigonometry rather than a simple diameter measurement.
What inputs does the Bolt Pattern Calculator need?
You'll need to provide: Bolt circle diameter (mm), Number of lugs. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Bolt Pattern Calculator?
The Bolt Pattern Calculator applies the formula exactly as calculated — Bolt spacing (mm) = bolt circle diameter (BCD) × sin(180°/lug count), using the standard trigonometric constants for common lug patterns (4-lug: 0.7071, 5-lug: 0.58779, 6-lug: 0.5). — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Bolt Pattern Calculator free to use?
Yes, the Bolt Pattern Calculator is completely free, requires no signup, and runs instantly in your browser.

About the Bolt Pattern Calculator

The Bolt Pattern Calculator uses a real, verifiable formula — Bolt spacing (mm) = bolt circle diameter (BCD) × sin(180°/lug count), using the standard trigonometric constants for common lug patterns (4-lug: 0.7071, 5-lug: 0.58779, 6-lug: 0.5). — so results are accurate every time, not an approximation.