The player's equity is his expected share of any pot.
The player's equity can be expressed as a percentage (probability of winning) or as an expected value (the amount of the pot * probability of winning).

There is also the negative equity also known as loss in equity. Negative equity means that the payer contributes to a pot and has a probability of winning less than 1 / number of opponents who match his bet.

Let's look at an example of player equity:

• John bets 12$ and two more players also call 12$. It is John's 12$ bet that bought the opportunity to win 36$.
• If the probability that John wins the pot is 50% his equity in the 36$ pot is 18$.
• This is a gain in equity because John's 12$ is now worth 18$).
• A loss in equity is when John's probability of winning is, for example 10% because then his 12$ would be worth only 3.6$.