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Bolt Circle Calculator

Compute X/Y coordinates of holes on a pitch circle from center point, PCD, hole count, and start angle. Output is ready for CNC programming and inspection.

Center X (mm)

Center Y (mm)

Pitch circle diameter (mm)

Number of holes

Start angle (deg, 0 = +X axis)

Direction

Radius (R)

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Angular spacing

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Hole #	Angle (°)	X (mm)	Y (mm)

Formula and use

X = Cx + R × cos(θ), Y = Cy + R × sin(θ)

R = PCD ÷ 2. Angular spacing = 360° ÷ N holes. θ_i = startAngle + (i − 1) × spacing (CCW positive).

Angles are measured from the positive X axis (right), counter-clockwise positive. In CNC G-code, use G17 plane with these absolute coordinates. Verify against your machine's coordinate convention before running a program.