Bolt Circle Calculator

Calculate coordinates for evenly spaced bolt holes on a circle. Export to CSV, SVG, and G-code for your projects.

Must be at least 1
Diameter (D)
Radius (R)
Must be greater than 0
Millimeters (mm)
Inches (in)
Advanced Options â–¼
Counterclockwise
Clockwise
Center (0,0)
Top-Left Pixel

Quick Presets

4 Holes
5 Holes
6 Holes
8 Holes
Car Wheel (5×114.3)
Car Wheel (4×100)

Results

Copied to clipboard!
Hole Angle (°) X Y Hole Dia

How It Works

The bolt circle calculator computes coordinates for evenly spaced holes on a circle using trigonometric functions.

Formulas

For evenly spaced holes across a full or partial circle:

Angle step = arcDegrees / number of holes

Coordinates (with R = D/2):

xi = X0 + R × cos(θi × π/180)

yi = Y0 + R × sin(θi × π/180)

where θi = startAngle + direction × (i-1) × angleStep

Examples & Templates

Common bolt circle patterns:

  • 4-hole pattern: Often used in flanges and simple fixtures
  • 5-hole pattern: Common in automotive wheel applications
  • 6-hole pattern: Standard for many industrial applications
  • 8-hole pattern: Used in high-load applications

FAQ

How do I measure Bolt Circle Diameter (BCD)? +

For an even number of holes, measure directly between opposite holes. For an odd number, measure from the center of one hole to a point halfway between the two opposite holes.

What’s the difference between chord and diameter? +

The chord is the straight line distance between two points on a circle, while the diameter is the longest chord that passes through the center of the circle.

What are common wheel lug patterns? +

Common patterns include 4×100, 5×100, 5×114.3, 6×139.7, where the first number is the number of holes and the second is the bolt circle diameter in millimeters.

Free for personal and commercial use. By CalculatorCave.