How it works
Pot odds compare what you pay with what you can win. If the pot is 100 and you need to call 50, you risk 50 to win 150: you need to win at least 33.3% of the time. Then the calculator counts your real chance of completing your hand with your outs, based on the cards still to come. If your chance is higher, the call makes money in the long run.
In the example that comes filled in, a flush draw (9 outs) on the flop has a 19.1% chance to complete on the turn. That’s less than the 33.3% the call needs: by the pot odds it’s a fold, unless you expect to win at least 111 more after you hit.
One card or two
If there can still be betting on the turn, count only the next card: that’s the price you’re paying now. Count the turn and river together only when your opponent is all-in and there will be no more betting. With 9 outs, the difference is big: 19.1% for one card and 35% for two.
Rake comes out of the pot
Rake is taken from the pot you win: with 5% rake, a pot of 150 pays 142.50. That makes your pot odds slightly worse in every hand you win. Rakeback gives part of that rake back every month and makes up for the difference. To see how much comes back at each site, use the rakeback calculator.