Understanding the Casino Odds

by Henry Tamburin

Casino gambling games are based on odds and probabilities. You don’t have to be a mathematician to play, but you should have some basic understanding of the “casino math” to help you select the best casino bets.

The probability of a given event is a measure of the likelihood of its occurrence. Take roulette for instance. The probability that the ball will land on number 7 in a typical 38 numbered roulette wheel is can be expressed as the ratio of 1 over 38 (ie.1/38). The ratio represents the chance that the ball will land in number 7 compared to it landing in all of the possible numbers (38 of them). In casino gambling, it is a common practice to refer to the “odds for something happening” and the “odds against something happening”. In our roulette example, the odds against the 7 winning is 37 to 1. You have 37 chances to lose for every 1 chance to win.

Every casino bet has specific payout odds. If you bet $10 in blackjack and are dealt a blackjack hand, the dealer will pay you $15. The payout odds for a blackjack are therefore 3 to 2 (you win $3 for every $2 bet). Likewise if you bet a dollar on number 7 in roulette and it wins you will be paid $35 (35 to 1 payoff odds). In some casino games the payff odds are listed on the layout (e.g. craps) or in the case of slot or video poker machines, they are listed on the face of the machine. Some casino bets have payoff odds of only 1 to 1 (you win equal money) like a winning blackjack bet, pass line in craps, or a bet on red or black in roulette. Other casino bets have payoff odds that are greater than 1 to 1(this means you’ll win more than a dollar for each dollar bet). For example our number 7 roulette bet has payout odds of 35 to 1 (you win $35 for every dollar bet).

When you see the payoff odds expressed as “to” (like 35 to 1) it means you win 35 chips and you get to keep the original 1 chip bet. Some casinos, especially in the game of craps, will post their payoff odds on the layout using the word ‘for” instead of ‘to”. Odds posted as 30 for 1, for example, means you win 30 chips but the casino keeps the original one chip bet. A 30 for 1 payoff therefore is the same as 29 to 1. If one casino lists the payoff as 30 for 1 and another as 30 to 1 for the same bet, you are better off at the casino that pays 30 to 1.

The casino has the edge or advantage on every bet because it pays out less than the true odds of winning the bet. We said earlier that the odds of winning a bet on number 7 in roulette is 37 to 1. If the payoff odds were the same, the casino would have no edge. By paying less than the true odds, the casinos ensure itself of a built-in edge. In the case of the number 7, the payoff odds are 35 to 1. The difference between the 37 to 1 true odds and 35 to 1 payoff odds creates an edge for the casino (in this example the casino keeps 2 chips for every 38 wagered on number 7 or a casino edge of 5.26%).

Tip #1: Just because a casino bet pays more when it wins than another bet does not necessarily mean it is a better bet.

Tip #2: The closer the payoff odds are for a specific casino bet compared to its true odds, the lower the casino’s edge.

Tip#3: Be careful of the word “for” in casino payoff odds. It gives the perception you are winning more but in reality you aren’t because the casino keeps the original bet.

Tip #4: You should always wager on casino bets that have the lowest casino edge. As a general guideline, only make bets in a casino where the casino’s edge is 1.5% or less.