How does it choose notes and coins?

It uses a greedy breakdown from the largest denomination down (100, 50, 20, 10, 5, 2, 1, then 0.50 to 0.01), which gives the fewest pieces for standard currency systems.

What if the customer underpaid?

If the amount paid is less than the amount owed, the tool shows how much more is still needed instead of a change breakdown.

Is anything sent to a server?

No: all calculations happen locally in your browser.

Change Maker Calculator

Work out change owed and the fewest notes and coins to give it.

Change maker calculator

Enter the amount owed and the amount paid, and this calculator shows the change due plus the smallest set of notes and coins to make it — counting down from large denominations to one cent.

It works for any currency that uses standard 1/2/5 style denominations, and runs entirely in your browser with nothing uploaded.