Bolt Circle Coordinate Layout Calculator

Method, example, and limits

Formula: For pitch diameter D and n holes, radius r = D/2, angle θᵢ = θ₀ + 360°i/n, xᵢ = r cos θᵢ, yᵢ = r sin θᵢ.

Inputs and units: D is pitch circle diameter, n is integer hole count from 3 to 360, and θ₀ locates the first hole counterclockwise from +x. Coordinates use the pitch-diameter unit.

Worked example: For D = 100 mm, six holes, and 0°, the radius is 50 mm and the first three centers are (50, 0), (25, 43.301), and (−25, 43.301) mm.

Result meaning: The listed x,y values are hole-center offsets from the circle center; the radius and equal angle spacing make the repeated pattern auditable.

Assumptions: All holes lie on one ideal circle at equal angular spacing. Coordinates are relative to the circle center; the entered start angle is not a clocking or datum specification for any particular part.

Limits: No hole diameter, positional tolerance, datum transformation, or manufacturing compensation is applied. Use the coordinates as geometric layout values, not a fabrication certification.