Enter the pot and the bet you are facing. Get the pot odds, the equity you need to call, and a plain-English read on whether to do it.
You need about 25% equity to break even on the call. A flush draw (~36%) or an open-ended straight draw (~32%) calls at a profit here; a gutshot (~16%) does not.
Pot odds compare what you can win to what you must pay. The formula is the bet you call divided by the pot after you call: equity needed = call ÷ (pot + call).
Say the pot has $150 in it and you face a $50 bet. You call $50 to play for a $200 pot, so you need 50 ÷ 200 = 25% equity. In ratio terms that is 3-to-1: the pot pays three chips for every one you risk. If your hand wins more than 25% of the time, calling makes money.
To know your equity, count your outs, the cards that make your hand, then use the rule of 2 and 4: multiply outs by 2 for the next card, by 4 for both cards to come. A flush draw has nine outs, so about 36% by the river. Compare that to the equity the pot asks for, and the call answers itself.
Divide the bet you must call by the total pot after your call. A $50 call into a $150 pot is 50 ÷ 200 = 25%. That is the equity your hand needs to make the call break even.
Good pot odds are ones your hand can beat. Getting 3-to-1 (25% needed) is great with a flush draw that wins 36% of the time. The same 3-to-1 is a fold with a gutshot that only hits 16%.
Pot odds are the price the pot offers you. Equity is how often your hand wins. You call when your equity is higher than the equity the pot odds demand, and fold when it is lower.