A simple calculator for working out how far a piston will move for a given number of degrees turn of a crankshaft. Originally put together out of curiosity; handy for folks that like to set timing using a DTI gauge or possibly just want to turn up a dead stop plug.

Measurements are in degrees and millimetres. Length 'L' is the distance between the centres of the big and little ends (not the total length of the rod!). Crank radius is half of the stroke. Note that the calculation is only accurate for non-offset cranks, being based on the triangle SCB in the diagram.

Changing any one of the three variables will update the distance from TDC.