Casino odds calculator

Use this casino odds calculator to find your chance of winning, the payout on a successful bet, and the mathematical house edge. Choose a roulette example or enter your own probabilities and payout ratio.

Winning probability and payout odds are different. Probability describes how likely a win is. Payout odds describe the profit paid when you win. A bet that pays 35:1 returns 35 times your stake as profit, plus your original stake.

Calculate casino odds and payouts

Enter the bet's probability and profit payout. A push means your stake is returned in full.

Example bet

Enter probability asUse counts only when all outcomes are equally likely.

Currency

Winning outcomes

Total outcomes

Push outcomesWins and pushes must be separate outcomes.

Bet amount

Profit payout ratio

35 to 1 means 35 times your stake in profit. Enter 3 to 2 for a 3:2 payout.

Standard single-zero rules: zero loses; no la partage or en prison.

This model assumes one fixed payout for every win, a full-stake loss for every loss, and a full refund for every push. It does not calculate a game's true probability from its name or account for multiple prize levels, commissions, partial refunds, or changing stakes.

How to calculate casino odds

When every outcome has the same probability, divide the number of winning outcomes by the total number of possible outcomes. Multiply the answer by 100 to express it as a percentage.

Win probability = winning outcomes ÷ total outcomes

For a single-number bet on a standard European roulette wheel, there is one winning number out of 37 pockets. The probability is 1 ÷ 37, or approximately 2.7027%. The other 36 pockets lose.

Counting outcomes does not work when those outcomes have different probabilities. For games involving cards, strategy, or multiple prizes, enter a probability calculated for the specific rules instead.

Calculating the payout and total return

For profit payout odds of a:b, the profit multiplier is a ÷ b. Your net profit on a win is the stake multiplied by that multiplier. The total return includes the stake as well.

Net profit on a win = stake × (a ÷ b)
Total return on a win = stake × (1 + a ÷ b)

What does a 35:1 payout mean?

A $10 bet at 35:1 produces $350 in net profit if it wins, with $360 paid back in total. If it loses, you lose the $10 stake. Decimal payout 36.00 expresses the same total return: $10 × 36 = $360.

Check also the casino payout calculator guide for the distinction between profit and total return.

Fair odds, expected value, and house edge

Let p be the win probability, q the push probability, r the profit payout multiplier, and S the stake. Probabilities in these formulas are decimals: 50% is 0.50. The loss probability is 1 − p − q.

Expected net value = S × [p × r − (1 − p − q)]
Theoretical RTP = [p × (1 + r) + q] × 100%
House edge = [1 − p × (1 + r) − q] × 100%

Expected value is the average net result per bet over many repetitions under these assumptions. RTP measures the expected proportion of stakes returned, including returned stakes on wins and pushes. Neither is a prediction for a single bet or a short session.

Fair profit payout multiplier = (1 − p − q) ÷ p
Break-even win probability = (1 − q) ÷ (1 + r)

The fair payout creates an expected value of zero for the entered probabilities. A negative house edge means the supplied assumptions produce a player advantage. It does not prove that those assumptions match an actual casino game.

European roulette example

For a $10 single-number bet with a 1/37 win probability and 35:1 payout, the expected net result is $10 × [(1/37 × 35) − 36/37] = approximately −$0.27 per bet. The theoretical RTP is 97.2973%, and the house edge is 2.7027%. A fair profit payout would be 36:1.

Common roulette odds

Standard roulette bet probabilities and house edges
Bet	Win probability	Profit payout	House edge
European single number	1/37 ≈ 2.7027%	35:1	2.7027%
European red or black	18/37 ≈ 48.6486%	1:1	2.7027%
American double-zero single number	1/38 ≈ 2.6316%	35:1	5.2632%
American double-zero red or black	18/38 ≈ 47.3684%	1:1	5.2632%

These examples assume standard payouts and full losses on zero or double zero. Special rules such as la partage, en prison, or multiplier payouts require a different model.

Frequently asked questions

Can I calculate win probability from payout odds alone?

You can calculate a break-even probability, but not necessarily the true chance of winning. With no pushes, break-even probability is 1 ÷ (1 + the profit multiplier). A 35:1 payout implies a break-even probability of 1/36, while a European roulette single-number bet actually wins with probability 1/37.

Is RTP the same as the probability of winning?

No. RTP depends on both probabilities and amounts returned. Two bets can have very different win probabilities and still have the same theoretical RTP.

How do I enter a push?

Enter the chance or number of outcomes that return your original stake with no profit or loss. Pushes are separate from wins. Do not use this field for partial refunds.

Can this calculator calculate blackjack or slot odds?

Only if the entered probabilities and fixed payout accurately describe the bet. A full blackjack game can have several payouts and player decisions. A slot can have many prize levels. Those games need a weighted calculation over all outcomes rather than one winning payout.