Disclaimer: This blog may contain affiliate links. If you click on these links and make a purchase, we may earn a small commission at no extra cost to you. And remember - we only recommend products we trust and believe will benefit you!
Getting into sports betting can be exciting, but it all starts with understanding the odds. Odds are how we measure the likelihood of something happening and how much we could win from a bet.
In this guide, we’ll break down the three main types of odds you’ll see: American odds, Decimal odds, and Fractional odds, and explain how each works in a way that’s easy to understand.
American Odds
American odds (also called moneyline odds) are mostly used in the U.S. They’re a bit different because they show either how much you could win, or how much you need to bet to win a certain amount. They can be positive or negative, and they’re pretty easy to calculate once you get the hang of it.
Positive American Odds (+)
Positive odds tell you how much profit you’ll make on a $100 bet. For example, +150 means if you bet $100, you’ll win $150 in profit if you win the bet.
Formula
Payout = Bet x (Odds ÷ 100) + Bet
So if you had a $100 bet at +150 odds, it’d look like this:
Payout = 100 x (150 ÷ 100) + 100 = $250
You could win $150 profit plus your $100 bet back.
Negative American Odds (-)
Negative odds show you how much you need to bet to win $100 in profit. For example, -200 means you need to bet $200 to win $100 in profit.
Formula
Payout = Bet ÷ (Odds ÷ 100) + Bet
So if you had a $200 bet at -200 odds, it’d look like this:
Payout = 200 ÷ (200 ÷ 100) + 200 = $300
You could win $100 profit plus your $200 bet back.
Decimal Odds
Decimal odds are popular in Europe, Canada, and Australia. They’re the easiest to understand. The number shows you the total amount you’ll get back from a $1 bet, including both your stake and your profit.
How Decimal Odds Work
For example, 2.50 means that for every $1 you bet, you’d get $2.50 back if you win (this includes your $1 stake and $1.50 profit).
Formula
Payout = Bet x Decimal Odds
So if you had a $100 bet at 2.50 decimal odds, it’d look like this:
Payout = 100 x 2.50 = $250
You could win $150 profit plus your $100 bet back.
Fractional Odds
Fractional odds are used in the UK and Ireland. They show how much you can win compared to how much you bet. For example, 3/1 odds mean for every $1 you bet, you could win $3 in profit.
How Fractional Odds Work
For 1/4 odds, you need to bet $4 to win $1 in profit. This is common for favourites.
Formula
Payout = Bet x (Numerator ÷ Denominator) + Bet
So if you had a $100 bet at 3/1 odds, it’d look like this:
Payout = 100 x (3 ÷ 1) + 100 = $400
You could win $300 profit plus your $100 bet back.
Implied Probability
Implied probability is a percentage that tells you the likelihood of an outcome based on the odds. It helps you understand the odds beyond just how much you can win.
How to Calculate Implied Probability
For Positive Odds
Implied Probability = 100 ÷ (Odds + 100)
If the odds were +150:
Implied Probability = 100 ÷ (150 + 100) = 40%
For Negative Odds
Implied Probability = Odds ÷ (Odds – 100)
If the odds were -200:
Implied Probability = 200 ÷ (200 – 100) = 67%
For Decimal Odds
Implied Probability = 1 ÷ Decimal Odds
If the odds were 2.50:
Implied Probability = 1 ÷ 2.50 = 40%
For Fractional odds
Implied Probability = Denominator ÷ (Denominator + Numerator)
If the odds were 3/1:
Implied Probability = 1 ÷ (1 + 3) = 25%
Odds Conversion
Sometimes, you’ll see odds in different formats. Here’s how to quickly convert between them:
American to Decimal Odds
Positive: (Odds + 100) ÷ 100 + 1
Negative: 100 ÷ |Odds| + 1
Decimal to Fractional Odds
(Decimal – 1) as a fraction (e.g., 2.50 becomes 3/2)
Fractional to American Odds
For odds over 1: Fraction x 100
For odds under 1: -100 ÷ Fraction
Why Do Odds Vary Between Sportsbooks?
You might notice that odds are slightly different across various sportsbooks. This happens because:
Different Opinions: Bookmakers may see things differently based on their analysis.
Betting Volume: If many people are betting on the same outcome, the odds may change to balance things out.
Market Shifts: If something changes (like a key player injury), odds can shift to reflect new information.
Wrapping Up
Now that you understand the basics of American, Decimal, and Fractional odds, you’re ready to dive into sports betting with confidence! Whether you’re comparing odds or figuring out the best bets, understanding the numbers behind the odds is a great first step to becoming a smarter bettor. Good luck, and enjoy the game!
