Calculate coordinates for holes in a circular pattern (Pitch Circle).
Circle Parameters
°
Bolt Coordinates
Enter circle parameters to see coordinates
About this calculator
Overview
A bolt circle (or Pitch Circle Diameter, PCD) is a circular layout of holes. This pattern is commonly used in mechanical engineering for flanges, wheel hubs, and engine components.
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Pro Tips
To check your measurements, measure distance between two opposite holes (on center) to find the diameter.
The starting angle is usually 0° (horizontal to the right) or 90° (top center).
For precise fitting, always use a center punch before drilling.
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Fun Facts
"The 'Pitch Circle' is an imaginary circle that passes through the center of all the bolt holes."
"Most automotive wheels use 4, 5, or 6 lug patterns on specific bolt circle diameters (e.g., 5x114.3mm)."
"Machinists often use a 'Dividing Head' or 'Rotary Table' to create these patterns manually."
Formula: X = CX + R × cos(Angle)
Y = CY + R × sin(Angle)
Spacing = 2 × R × sin(180 / N)
