Estimate chord spacing and angular pitch on a pitch-circle diameter for equally spaced holes.
| Spacing | – |
| Pitch (°) | – |
Use this calculator to lay out holes on a flange or a PCD. Enter the pitch-circle diameter, the hole count, and a start angle (kept for layout notes; it does not change spacing).
Angular pitch = 360° ÷ count. Chord = PCD × sin(pitch ÷ 2). PCD can be entered in millimetres (mm) or inches (in). Spacing follows the same unit.
This is equal spacing on a circle. It does not output XY coordinates from the start angle.
PCD: Pitch-circle diameter, in mm or in.
Count: Number of equally spaced holes.
Start angle (°): First-hole angle for notes; unused in the spacing formula.
Spacing: Chord between adjacent holes.
Pitch: Angular pitch in degrees.
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