How to Use Percentages Instead of Odds in Online Gambling

min read
Two red and white dice on a green felt table.
BetMGM Oct 20, 2021, 8:36 AM

Odds are the bedrock of gambling. They provide the information you need to figure out the chances of your wager succeeding or failing. They also help you to calculate how much you will win if your bet succeeds. You have a much better chance of developing a good strategy for sports betting or casino games if you understand the odds. But odds can be tricky to work with. They tell you how much money you can win or lose, but they don’t tell you clearly what your chances are of winning the bet. 

That’s why many players make betting decisions based on percentages. If you know the percentage probability of success or failure, it’s much easier to make an informed choice when you’re playing casino table games and online slots. This blog looks at how to convert odds to percentages and apply them to any online casino situation. Read on for more.

Betting odds explained

So how do betting odds work? Odds are ratios of your chances of losing against your chances of winning. They can be expressed as fractions, decimals, or moneyline odds (American odds).

The fractional odds for a coin toss are 1/1, which means you have the same chance of winning as you do of losing. That’s simple enough, but things can get complicated quite quickly. Let’s take a simple example. If you own 1 of 4 tickets, you have a 1 in 4 chance to win, but your odds are 3/1. How sure would you feel about betting on a horse with odds of 4:3? What about a horse with odds of 1/3? It isn’t obvious that the probability of this bet succeeding is 75%.

It’s even less obvious when you’re working with American odds and decimal odds. Odds of 1/3 convert to American odds of -300. That means you have to put down $300 to win $100. This shows that our hypothetical horse is a favorite, but it’s not much help if you’re trying to work out the actual percentage probability of a win.

How to convert fractional odds

If you’re looking to work with percentages instead of odds, the good news is that it’s easy to convert from one to another. All you need to do is apply a mathematical formula. It’s simple enough to do on a calculator.

Here’s how to convert fractional odds to figure out the probability of a win. First, add the numbers on each side of the fraction together. Divide 1 by the result and multiply by 100. Let’s do that with odds of 3/1. Add 3 + 1 to get 4. Divide 1 by 4 to get 0.25. Multiply 0.25 by 100 to get 25. The probability of a win is 25%.

How to convert American odds

The method of converting American odds to percentages depends on whether you have positive (underdog) or negative (favorite) odds. Positive odds show how much you’ll win on a bet of $100. Negative odds show how much you need to wager to make $100.

To convert positive odds into percentages, divide 100 by the odds + 100, and multiply the result by 100. For odds of 300, you divide 100 by 400 to get 0.25 and multiply that by 100 to get 25%.

For negative odds, you divide the odds by the odds +100 and multiply by 100. Let’s work with odds of -300. Divide 300 by 400 and multiply by 100. The result is a 75% probability of a win.

How to convert decimal odds

Decimal odds come in decimal form (1.80, 3.50, 6.40, and so on). They’re also geared more to payouts than probabilities. To calculate how much a winning bet will pay, simply multiply it by your bet. Put $100 on a bet with decimal odds of 1.50, and you’ll get $150 if you win.

To work out your chances of winning from decimal odds, simply divide 100 by the odds. So decimal odds of 1,50 would yield an impressive winning probability of 66.67%! If you’ve got decimal odds of 10, your chances to win are exactly 10%.

The alternative to calculating percentages yourself is to use an online odds converter.

Playing with percentages

Using percentages is very useful in sports betting, but it can help a lot with online casino games too. The most important percentage to keep in mind is the house edge. That’s the average amount of money that the casino makes on a particular game over a certain number of plays, usually in the millions. Some games tell you straight up what the house edge is. 

Real online slots all come with an RTP (return to player) percentage. That’s the money the game gives back on average. Flip it around, and you get the house edge. Asgardian Stones, for example, has an RTP of 96.1%, so the house edge is 3.99%. Gonzo’s Quest has an RTP of 95.97%, so the house edge is slightly more.

Dig a little deeper, and you’ll find that as much fun as online slots can be, they’re not the casino games with the best odds. That honor goes to casino table games. The house edge on the banker hand in baccarat, for instance, is 1.06%, while it’s 2.7% for an even money bet on French Roulette, and it can go as low as half a percent for blackjack and video poker. But the best online casino bet in the house has to be “craps odds.” It’s the only bet where there’s no house edge at all.

Of course, recreational gambling is all about enjoying yourself, and sometimes it’s more fun to take a chance on a riskier bet than to always play it safe. But it always helps to know the percentage probability of winning when you’re playing at an online casino for real money. Your betting decisions will improve, and your bankroll will last longer, so you’ll have a better time.

Convert your gaming experience to premium at BetMGM

Now that you’ve had percentages and betting odds explained, why not put your knowledge into practice? Play all the casino games with the best odds when you sign up at BetMGM. We’ve got a broad range of premium online slots and live dealer casino table games for your entertainment, and they’re all optimized for mobile, so you can convert your couch into a real live casino. 

Actress Vanessa Hudgens flipping casino chips next to the text "The King of Casinos"
About the Author


Read More

Our BetMGM editors and authors are sports experts with a wealth of knowledge of the sports industry at all levels. Their coverage includes sports news, previews and predictions, fun facts, and betting.

Our BetMGM editors and authors are sports experts with a wealth of knowledge of the sports industry at all levels. Their coverage includes sports news, previews and predictions, fun facts, and betting.