Odds tell you two things at once, how much a bet pays and how likely the sportsbook thinks the outcome is. So, learning how to read betting odds is essential.
Up to $1,500 first bet offer
If your first bet loses
21+ in OH. $10 min bet req. Bonus Bets non-withdrawable, expire 7 days after receipt. T&Cs apply. Gambling Problem? Call 1-800-GAMBLER.
Bet $5 Daily
Get $1,000 in Bet Resets
21+ in OH. $5 min deposit req. Bonus Bets non-withdrawable, expire 7 days after receipt. T&Cs apply. Gambling Problem? Call 1-800-GAMBLER.
Bet $1
Get 10x Profit Boosts
21+ in OH. $1 min bet req. Profit Boosts expire 14 days after receipt. T&Cs apply. Gambling Problem? Call 1-800-GAMBLER.
Bet $5
Get $200 in Bonus Bets Instantly
21+ in OH. $5 min bet req. New Customer Offer Token expires 7 days after offer expiration. T&Cs apply. Gambling Problem? Call 1-800-GAMBLER.
$1,000 First Bet Safety Net
or Bet $10 get $150 in Bonus Bets Win or Lose
21+ in OH. Bonus Bets expire 7 days after receipt. T&Cs apply. Gambling Problem? Call 1-800-GAMBLER.
Odds come in three formats, and once you can read all three you can compare any price, in any market, anywhere.
- American odds (+/-) show profit on a 100 stake, or what you must risk to win 100.
- Decimal odds show your total return, stake included.
- Fractional odds show profit relative to your stake.
The same price looks different in each format but means exactly the same thing. A selection at +200 is also 3.00 and 2/1, and all three imply the same chance of winning. The rest of this guide walks through each format, how to convert between them, and how to turn odds into a probability you can utilize.
What Odds Actually Tell You
Odds are not just a payout number. They are the sportsbook’s estimate of probability, with its own margin built in, expressed as a price. Read them well and you can do three things most bettors skip, calculate the real return before you stake, compare the same bet across books, and spot the times the price is better than the outcome deserves.
When I started out I made the most common mistake there is, I confused profit with total return. Seeing +200 I thought a 100 bet handed back 200. It returns 300, the 200 profit plus your original 100 stake. Getting that distinction straight is the whole foundation, because every format below is just a different way of showing the same two facts.
Sportsbooks set these prices from statistical models, team data, injury news and, crucially, how money is coming in. Prices then move to balance the book. Knowing how to read them is what lets you react to a line move on purpose instead of chasing it.
American Odds Explained
American odds are the default in the United States and use a plus or minus sign to separate underdogs from favourites.
- Positive odds (the underdog) show the profit on a 100 stake. At +150, a 100 bet returns 150 profit, 250 in total. The bigger the number, the longer the odds and the larger the payout. So what does +200 mean? A 100 bet wins 200 profit, 300 back in total, and the book rates that outcome as less likely.
- Negative odds (the favourite) show what you must stake to win 100. At -150, you risk 150 to win 100, returning 250 in total. The minus simply means a higher chance of winning for a smaller reward.
A quick mental shortcut, for positive odds, divide by 100 to get profit per 1 staked (+200 means 2 profit per 1). For negative odds, divide 100 by the number (-200 means 0.50 profit per 1).
Decimal Odds Explained
Decimal odds are standard across Europe, Australia, Canada and most of the world, and they are the easiest to calculate with. The number is your total return per 1 staked, stake included.
The maths is one step, stake multiplied by the decimal price. A 100 bet at 2.50 returns 250, so 150 profit. Nothing to add on afterwards, which is exactly why I default to decimal whenever I am comparing prices across several books at once. Anything above 2.00 is an underdog (the equivalent of positive American odds), anything below 2.00 is a favourite. 3.00 equals +200, 1.50 equals -200.
Because the total return is always on screen, decimal is the format that makes line shopping fastest, you can see at a glance which book pays more on the identical outcome.
Fractional Odds Explained
Fractional odds are traditional in the UK and Ireland and still the language of horse racing. They show profit relative to stake as a fraction, like 5/1 or 3/2.
Read 5/1 as five profit for every one staked. A 20 bet at 5/1 returns 100 profit, 120 in total. A 2/1 favourite returns 2 profit per 1, an evens shot (1/1) doubles your money. Racing prices think in these ratios, which is why a longshot at 10/1 and a favourite at 2/5 sit side by side on the same board.
To convert a fraction to decimal, divide the top by the bottom and add 1, 5/1 becomes 6.00, 3/2 becomes 2.50.
How to Convert Between Odds Formats
Every format is the same probability wearing different clothes, so converting lets you compare like for like no matter how a book displays its prices. The manual routes are worth knowing even if you lean on a tool:
- American to decimal, for positive odds, divide by 100 and add 1 (+200 to 3.00). For negative odds, divide 100 by the number and add 1 (-200 to 1.50).
- Decimal to fractional, subtract 1 and express as a fraction (2.50 to 1.5/1 to 3/2).
- Fractional to decimal, divide and add 1 (3/1 to 4.00).
In practice I do not do this by hand mid-bet. The fastest way is our odds converter tool, which switches a price between all three formats and shows the implied probability at the same time. Use whichever format you find clearest, then convert when you need to compare.
Odds Comparison:
| American | Decimal | Fractional | Implied probability | Profit on 100 |
| +100 | 2.00 | 1/1 | 50% | 100 |
| +150 | 2.50 | 3/2 | 40% | 150 |
| +200 | 3.00 | 2/1 | 33.3% | 200 |
| +300 | 4.00 | 3/1 | 25% | 300 |
| -110 | 1.91 | 10/11 | 52.4% | 90.91 |
| -150 | 1.67 | 2/3 | 60% | 66.67 |
| -200 | 1.50 | 1/2 | 66.7% | 50 |
| -300 | 1.33 | 1/3 | 75% | 33.33 |
Turning Odds Into Probability
This is the part that changed how I bet. Every price implies a probability, and once you can read it you stop betting on names and start betting on value.
The formulas are short:
- Positive American, 100 divided by (odds + 100). +200 to 100/300 to 33.3%.
- Negative American, odds divided by (odds + 100). -150 to 150/250 to 60%.
- Decimal, 1 divided by the price. 2.50 to 40%.
- Fractional, denominator divided by (numerator + denominator). 3/1 to 1/4 to 25%.
Once you have the implied probability, compare it to your own read of the game. If you think a team’s real chance is higher than the price implies, that is where value lives. It does not mean backing longshots blindly, it means betting only when your estimate beats the book’s. That single habit, checking the implied probability before staking, is the one tip that has helped me most over time.
Common Mistakes to Avoid
-
Confusing profit with total return. Winning 200 profit at +200 means 300 back, stake included. This is the error I made earliest and it wrecks bankroll maths if it goes unchecked. A bankroll calculator keeps stake sizing honest.
-
Misreading negative odds. A minus price is not a bad bet, it is a favourite. It just shows the stake needed to win 100, so do not overcommit to short prices thinking they are safe money.
-
Ignoring the vig. Two evens outcomes priced at -110 each rather than +100 is the book’s margin, the juice. Paying it repeatedly erodes a bankroll quietly, so it pays to notice it.
-
Not shopping the line. The same outcome is often priced differently across books. Comparing before you stake is the highest-value habit in betting, and converting to one format makes the comparison instant.
Pro Tips From Testing
The single habit that has done most for my own results is line shopping. Prices on the same game drift between books, and over a season those small gaps compound. I keep two or three accounts open purely so I can take the best available price rather than the first one I see.
Understanding the vig is the other one. The book’s margin is baked into the odds, so a pair of evens outcomes shown at -110 each is the commission at work. Spotting when a price is inflated, usually on heavily backed favourites, stops you overpaying for the popular side.
And value is not a feeling. It exists only when the odds imply a lower probability than your own research says is realistic. Pairing that check with disciplined staking is, in my experience, the difference between betting for fun and betting well.
Try the Odds Converter
The quickest way to lock all of this in is to practise with real prices. Our odds converter switches any price between American, decimal and fractional and shows the implied probability alongside, so you can see how the formats relate without doing the maths by hand. Enter a price in any one format, add your stake, and it returns the profit, the total return and the probability the book is pricing in.
Odds Converter Calculator
Keep Learning
Reading odds is the foundation, the next step is putting it to work across markets.
FAQs
How do odds work in betting?
Odds show both the payout and the implied chance of an outcome. Longer odds mean a lower probability and a bigger return, shorter odds mean a favourite with a higher chance but a smaller reward.
What does +200 mean in betting?
A 100 bet at +200 wins 200 profit, 300 in total including your stake. Positive odds mark an underdog and a larger potential payout.
What do negative odds mean?
Negative odds show the stake needed to win 100. At -150 you risk 150 to win 100. They indicate a favourite with a higher implied probability.
Which odds format is easiest for beginners?
Decimal is the most straightforward, since the number is your total return per unit staked. American odds are clearest if you think in terms of a 100 stake.
How do I calculate my payout from odds?
Multiply your stake by the decimal price for the total return. For American odds, positive numbers show profit on 100, negative numbers show the stake needed to win 100.
Why do odds change before an event?
Odds move with injuries, team news, weather and the weight of money coming in, as the book balances its position. That is why an early price and a late price on the same event can differ.
What is the difference between odds and probability?
Odds show the potential payout, probability shows the likelihood of the outcome. Implied probability converts the odds into a percentage so you can judge whether a price offers value.
