PCD calculator is very handy app to calculate PCD, Chord Length and Flange Holes easily.

1) The PCD (pitch circle diameter) for given number of studs, wheel bolts or wheel rim holes
2) Chord length for given PCD and number of studs, wheel bolts or wheel rim holes
3) Number of studs for given PCD and chord length
4) Arc length

Useful for Flange making.