Hole coordinates are calculated from the bolt-circle radius using standard Cartesian geometry. A start angle of 0° is on +X; positive angular progression is counter-clockwise unless clockwise direction is selected.

Chord geometry uses the standard circle relationship Chord = BCD × sin(Angle ÷ 2). The same relationship is rearranged to recover included angle or BCD. For equally spaced patterns, the included angle is 360° × hole separation ÷ total holes.

The Bolt Circle tool reports adjacent-hole chord as pattern information. The Chord Geometry tool handles reverse BCD calculations and chord measurements across multiple hole positions.

Incremental coordinates show movement from the pattern center to Hole 1, then from each hole to the next hole in the selected direction.