Optimal Change Calculator

Closing time and you need to build the cash drawer's change float. Or you are heading to the bank and want to know how many notes of each kind you will walk out with. Mental math holds up until an odd amount like 187.43 shows up. Type the amount in reais and the page returns the combination with the fewest possible Brazilian notes and coins, from the 200 note down to the 1 centavo coin.

The method is greedy: it always takes the largest piece that fits what is left, then repeats. Greedy is not always minimal. In a made up system with coins of 1, 3 and 4, making 6 the greedy way costs 4+1+1, three coins, while 3+3 does it in two. The real escapes that trap because its denominations form a canonical system: with 200, 100, 50, 20, 10, 5, 2, 1, 0.50, 0.25, 0.10, 0.05 and 0.01, greedy always lands on the minimum.

The field expects the change amount already worked out. The page does not subtract what the customer handed over from what was owed, that part is on you. It also assumes an unlimited supply of every piece, so if the drawer has run out of 50s the answer is useless. Watch the two ends of the list: the 200 note and the 1 and 5 centavo coins barely circulate in Brazil. Everything is computed in your browser.