The ideal payout for an online casino craps player would be the mathematically true payout. But online casinos have to cover costs and make a profit. Therefore they offer payouts on craps bets that are less than the mathematically true payouts. The house edge of a bet is a measure of how much the actual payout is lower than the mathematically true payout. Therefore, when online casino players wager on craps they must select the bets with the lowest house edges.

Unfortunately online casinos do not report the house edges of the various bets they offer. They only state the actual payouts. It is up to the online casino player to calculate the house edge and select the bet. The first step in calculating the house edge is calculating the probability of the bet winning. This probability is the ratio of the number of ways in which a favorable result can be obtained compared to the total number of out comes. Many of the bets in online craps involve a single roll of a pair of dice. A two can be rolled in 1 way, a three can be rolled in 2 ways and a four can be rolled in 3 ways. When the numbers of ways for rolling totals from two to twelve are added up the total number of outcomes is 36.

A common one roll bet in online craps is Any Seven. This bet wins if a seven is rolled. A seven can be rolled in 6 ways. Hence there are 6 favorable outcomes. The total number of outcomes is 36. Hence the probability of rolling a seven is 6/36 or 1/6. Online casinos offer a payout of 4 to 1 for a bet of Any Seven. A simple way of calculating the house edge is as follows. Suppose that a player bets $1 on Any Seven. Because the probability of winning is 1/6, in the long run the player will win once and lose five times. When he wins he will get $4 and when he loses five times he will pay $5. Therefore on a total investment of $6 he will lose $1. Therefore his house edge for this bet is 1/6 or 16.67%. In the case of a mathematically true payout the house edge will be zero. The mathematically true payout for a bet of Any Seven is 5 to 1. When the player wins he will get $5 and when he loses five times he will pay $5. Hence in the long run he will neither win nor lose.

Some bets in online craps win if any of a given set of numbers is rolled. One such bet is Any Craps. This bet wins if the total rolled is two, three or twelve. A two and twelve can be rolled 1 way each and a three can be rolled in 2 ways. Therefore the number of favourable outcomes for Any Craps is 4. Hence the probability of rolling Any Craps is 4/36 or 1/9. Online casinos offer a payout of 7 to 1 for a bet of Any Craps. Suppose that a player bets $1 on Any Craps. Because the probability of winning is 1/9, in the long run the player will win once and lose eight times. When he wins he will get $7 and when he loses eight times he will pay $8. Therefore on a total investment of $9 he will lose $1. Therefore his house edge for this bet is 1/9 or 11.11%.