Pot odds are the ratio between what you stand to win and what you must pay to stay in. Required equity is the same statement as a percentage, and it is the more useful form, because it is directly comparable to your chance of winning the hand.
The formula
Call an amount B into a pot of P. If you call, the pot becomes P + 2B, of which you have contributed B. Break-even is where your share of the time you win covers your share of the money:
required equity = B / (P + 2B)
The ratio version is the same fact turned round: you are being offered (P + B) to B, which reduces to (P + B) / B to 1.
The most common error here is arithmetic on the wrong pot. If the pot is 100 and someone bets 50, you are not getting 2 to 1 on your money; you are getting 3 to 1, because the 50 they just bet is now part of what you win. Count the bet you are facing as part of the prize.
The bet-size table
Almost all bets are some conventional fraction of the pot, so the answers repeat. These six lines cover most decisions you will ever face.
| Bet size | Pot odds | Equity you need | A bluff must work | Minimum defence |
|---|---|---|---|---|
| One third pot | 4 : 1 | 20.0% | 25.0% | 75.0% |
| Half pot | 3 : 1 | 25.0% | 33.3% | 66.7% |
| Two thirds pot | 2.5 : 1 | 28.6% | 40.0% | 60.0% |
| Three quarters pot | 2.33 : 1 | 30.0% | 42.9% | 57.1% |
| Pot | 2 : 1 | 33.3% | 50.0% | 50.0% |
| Twice pot | 1.5 : 1 | 40.0% | 66.7% | 33.3% |
Two of those columns describe the bettor rather than the caller, and they are worth reading together. A half-pot bluff risks 50 to win 100, so it needs to succeed a third of the time to break even. That is why small bluffs are cheap and large bluffs are expensive, and why an overbet is a genuine commitment rather than a stylistic flourish.
Minimum defence frequency is the mirror image: the proportion of your range you must continue with so that a pure bluff makes no money. Facing a pot-sized bet, folding more than half the time means anyone can bet any two cards into you profitably. It is a bound, not a target — against an opponent who never bluffs you should fold far more than MDF says, and lose nothing by it. The number tells you what an unexploitable defence looks like, which is the baseline you deviate from on purpose rather than by accident.
Implied odds, and when they are a real argument
Pot odds only price the money already in the middle. Implied odds account for money you expect to win on later streets when you hit. They are the legitimate reason to call a draw that the immediate price rejects.
The conditions under which they are real, rather than an excuse:
- Your hand is disguised. A flush completing on a three-suited board is visible to everyone; the bottom end of a straight is not.
- Stacks are deep enough to matter. If the effective stack is a fraction of the pot, there is no future money to win and implied odds are approximately zero. This is why drawing works in deep cash games and fails in a shallow tournament.
- Your opponent has a hand they cannot fold. Implied odds require a payer. Against someone who checks back the river with one pair, the extra bet you were counting on does not exist.
Reverse implied odds are the same idea pointing the other way, and get discussed a tenth as often. When you call with a hand that will win a small pot and lose a big one — a weak ace, a low flush draw — future betting costs you money rather than making it. The correction is to require better immediate odds than the raw calculation demands, not worse.
Where this goes next
The number the calculator hands you is only half of a decision; the other half is your actual chance of winning, which means counting outs. In a tournament there is a further correction, because the chips you are risking are not worth the same as the chips you would win — see ICM.