Odds: casino meaning explained

What odds mean in a casino

Odds are a way of writing chance as a ratio. “Odds against” put the losing outcomes first: if a bet has 36 ways to lose and 1 way to win, the odds are 36 to 1 against. Probability puts the same information differently, as wins out of all outcomes: 1 in 37, or 2.70%.

Casinos use the word in two senses, and mixing them up is the most common mistake in our casino glossary. True odds describe how likely the bet is to win. Payout odds describe what the casino pays when it does. In a fair game they would match; in a casino game the payout is always a little short, apart from rare exceptions such as the craps free odds bet.

Converting odds, probability and decimal prices

Every bet can be written three ways. For a chance p, the odds against are (1 − p) ÷ p to 1, and the fair decimal price (stake included) is 1 ÷ p. Here they are for common single-zero roulette bets, using the probabilities in Wizard of Odds’ roulette basics (opens in a new tab):

Our odds formats guide covers fractional, decimal and percentage forms in more depth.

“To 1” against “for 1”: reading payout odds

Payout odds written “to 1” give your winnings only, and your stake comes back on top. A £10 straight-up at 35 to 1 returns £360: £350 won plus your £10. Odds written “for 1” include the stake, so “8 for 1” returns £8 for every £1, which is the same as 7 to 1. Live games sometimes use a multiplier instead: Evolution’s First Person Lightning Roulette page (opens in a new tab) says a straight-up “pays 30x”, which most likely means a 30x total return, the same as the 29 to 1 shown on the live version.

How the gap between odds becomes the house edge

Hannum and Cabot’s textbook Casino Math gives a neat formula: when a bet pays x to 1 and the true odds are y to 1, the house advantage is (y − x) ÷ (y + 1). Try it on bets from the house edge table:

The craps figures match Wizard of Odds’ craps house edge table (opens in a new tab). The odds bet is the one standard casino bet paid at true odds, which is why it carries no edge; you can only make it after a pass or come bet, which do carry one.

What the odds gap costs in pounds

Expected loss is stake × house edge. A £5 straight-up on a single-zero wheel loses 13.5p on average per spin; on a double-zero wheel, 26.3p. Over 60 spins an hour that is about £8.10 against £15.78, purely because of one extra pocket. The cost per hour page and the house edge calculator let you run your own numbers.

Casino odds and our partner offers

Knowing the odds helps you judge any game, but our partner offers are mainly slot offers rather than table promotions. Roulette, craps and live tables are often excluded from bonuses or count for less towards wagering, so read the full terms. 18+ and terms apply.

• Casumo’s new-customer offer is 50% up to £100 on a first deposit of at least £20, opt-in required, with 10x wagering on the bonus inside 7 days, a £5 per-bet limit while it runs, and game, play and payment restrictions.
• 10bet offers a 100% first-deposit match up to £25 to new UK customers who select the casino welcome bonus when signing up and deposit within 7 days; wagering is 10x on slots within 3 days, the most you can win from the bonus is £1,000, and Skrill and Neteller deposits are left out.
• Coral gives 100 free spins to new players who deposit and stake £10 or more on slots; each spin is worth 10p on selected games, the spins must be accepted within 48 hours and used within 7 days, and winnings carry no wagering. Neteller, PayPal, Paysafe, Skrill, prepaid cards and certain debit cards don’t qualify, and the promotion ends on 1 February 2027.

18+. Every casino game has a built-in house edge, so over time you should expect to lose what you stake. Set a budget before you play and stop when it’s gone: safer gambling tools and support. Free, confidential help: National Gambling Helpline 0808 8020 133.