⚙️ Bolt Circle Calculator
Find the arc spacing between bolts evenly arranged around a bolt circle, for flanges, wheels, and mounting patterns.
What This Calculator Does
When bolts are spaced evenly around a circular pattern (a flange, wheel hub, or pipe fitting), this tool calculates the straight-line distance between adjacent bolt holes and the angle between them.
The Formula
The angle between adjacent bolts is simply 360° / number of bolts. The straight-line (chord) distance between two adjacent bolts on a circle of radius r is chord = 2r × sin(angle / 2), which comes directly from the geometry of an isosceles triangle formed by the two radii and the chord.
This is a standard machining and fabrication reference used for laying out flange bolt patterns, wheel studs, and similar circular hole patterns. Always verify against the actual part drawing or specification before drilling.