Enter odds in any format and instantly convert to American, decimal, and fractional. See implied probability and breakeven win rate in one click. No signup required.
Converting odds formats is useful, but finding where you actually have an edge is the harder problem. Juice automatically compares odds across 18 sportsbooks in real time, estimates the true probability of each outcome using three AI models (ChatGPT, Claude, and Gemini), and calculates expected value for every bet. It turns the line shopping you would do manually into an automated process. Once you understand the formats, Juice handles the comparison for you.
Every sportsbook in the world uses one of three odds formats: American, decimal, or fractional. They all represent the same underlying information (how much you win relative to your stake) but express it differently. Being fluent in all three helps you compare lines across international books, understand value bets at a glance, and catch when a line is mispriced relative to its true probability.
If you are new to betting odds entirely, our complete guide to reading betting odds walks through each format in depth with examples and conversion formulas.
American odds are the standard format used by US-facing sportsbooks. They use positive and negative numbers to indicate underdogs and favorites, and the numbers represent how much you win or need to risk on a $100 basis.
Negative odds like -150 or -200 tell you how much you need to bet in order to win $100. A line of -150 means you must wager $150 to profit $100. The larger the negative number, the bigger the favorite.
Positive odds like +130 or +250 tell you how much you profit on a $100 bet. A line of +250 means a $100 bet wins $250 in profit (plus your original $100 back, so $350 total).
The Celtics are -130 favorites at FanDuel but +110 underdogs at a different book for some reason (a mispriced line). At -130, you need to risk $130 to win $100. At +110, a $100 bet wins $110. If you can get on the underdog side at +110, you are getting significantly better value than the market implies.
Decimal odds represent the total payout per unit staked, including your original bet. They are the dominant format in Europe, Australia, and Canada, and they are significantly easier to use for expected value calculations.
To calculate your payout: multiply your stake by the decimal odds. Subtract your stake to find your profit.
1.91 odds: A $100 bet returns $191 total ($91 profit). Equivalent to -110 American.
2.50 odds: A $100 bet returns $250 total ($150 profit). Equivalent to +150 American.
1.50 odds: A $100 bet returns $150 total ($50 profit). Equivalent to -200 American.
Decimal odds are particularly useful because implied probability is simply 1 divided by the decimal odds. At 2.50 decimal odds, implied probability is 1/2.50 = 40%. This makes quick mental math easier when scanning lines.
Decimal odds also make parlay math simple. A three-leg parlay at 1.91, 2.10, and 1.83 decimal odds pays out 1.91 x 2.10 x 1.83 = 7.34x your stake total, meaning a $100 parlay returns $734.
Fractional odds are the traditional format used in the UK and widely seen in horse racing worldwide. They express profit as a ratio to your stake. The first number (numerator) is your profit, and the second number (denominator) is your stake.
5/1 (five-to-one): Win $5 for every $1 staked. A $100 bet wins $500 profit.
5/2 (five-to-two): Win $5 for every $2 staked. A $100 bet wins $250 profit.
1/2 (one-to-two): Win $1 for every $2 staked. A $100 bet wins $50 profit. This is a favorite (less profit than staked).
Evens (1/1): Win $1 for every $1 staked. Equivalent to +100 American or 2.00 decimal.
When the numerator is larger than the denominator (e.g., 5/2), you are looking at an underdog. When the denominator is larger (e.g., 1/4), you are looking at a heavy favorite. Evens (1/1) means both sides are priced at exactly 50% before accounting for vig.
Behind every set of odds is a probability. The sportsbook is telling you, in mathematical terms, how likely they believe an outcome is. Learning to read odds as probabilities rather than payout ratios is one of the most important shifts a bettor can make.
At -110, implied probability is 110/210 = 52.38%. At +150, implied probability is 100/250 = 40%. These numbers represent what the sportsbook's line implies about the true probability of each outcome.
The key insight: sportsbooks deliberately inflate these probabilities above the true market probability to build in their margin. A standard -110/-110 spread market implies 52.38% + 52.38% = 104.76% total probability, which is 4.76% over 100%. That extra percentage is the vig the book collects over time.
Line shopping means comparing odds across multiple sportsbooks and taking the best available price before placing a bet. It is one of the most reliable ways to improve long-term profitability without needing to win more bets. Getting -105 instead of -110 on the same outcome improves your breakeven win rate from 52.38% to 51.22%, which compounds significantly over hundreds of bets.
This odds converter helps you compare lines across books even when they display odds in different formats. Some international books show decimal odds, UK-based books show fractional, and US books show American. Enter the odds from any book in whatever format it uses, and the converter instantly shows you all three alongside the implied probability. You can then make a direct comparison to find the best price.
You want to bet an NBA spread. Book A offers -110 (1.909 decimal, 52.38% implied). Book B offers -105 (1.952 decimal, 51.22% implied).
Over 500 bets at $100 each, if you win 54% of the time: at -110 your net is approximately +$820. At -105 your net is approximately +$1,430. That is a $610 difference from a single half-point of improvement in line value, with zero additional skill required.
For automated line shopping across 18 books simultaneously, Juice handles the comparison automatically and flags which book has the best available price for every bet you analyze.
| American | Decimal | Fractional | Implied Probability |
|---|---|---|---|
| -500 | 1.20 | 1/5 | 83.33% |
| -300 | 1.33 | 1/3 | 75.00% |
| -200 | 1.50 | 1/2 | 66.67% |
| -150 | 1.67 | 2/3 | 60.00% |
| -130 | 1.77 | 10/13 | 56.52% |
| -120 | 1.83 | 5/6 | 54.55% |
| -110 | 1.91 | 10/11 | 52.38% |
| +100 | 2.00 | 1/1 (Evens) | 50.00% |
| +110 | 2.10 | 11/10 | 47.62% |
| +120 | 2.20 | 6/5 | 45.45% |
| +130 | 2.30 | 13/10 | 43.48% |
| +150 | 2.50 | 3/2 | 40.00% |
| +200 | 3.00 | 2/1 | 33.33% |
| +300 | 4.00 | 3/1 | 25.00% |
| +500 | 6.00 | 5/1 | 16.67% |
Convert decimal to fractional by subtracting 1, then expressing the result as a simplified fraction. For example, 2.50 becomes (2.50 - 1) = 1.50, which as a fraction is 3/2. For 1.909, it becomes approximately 10/11 after simplification.
Most recreational bettors only ever deal with American odds at US books. But being comfortable across all three formats opens up meaningful advantages:
Access to international books. Pinnacle, Bet365, and other offshore books often have sharper lines and lower vig than US books. They display decimal odds. Being able to read and compare those lines directly without needing a converter in your head means you can shop more effectively and identify when the US market is mispriced relative to the global consensus.
Faster mental EV checks. Decimal odds make expected value math easier to run in your head. At 2.50 decimal odds, implied probability is exactly 40%. At 1.91, it is just under 52.5%. Once you internalize a handful of common decimal odds conversions, you can gut-check lines instantly without formal calculation.
Horse racing and futures markets. Fractional odds still dominate horse racing coverage and appear frequently in futures markets. Understanding them means you can evaluate horse race value bets and identify mispriced championship futures using the same probability framework you apply to game lines.
Parlay construction. Decimal odds simplify parlay math dramatically. Multiply the decimal odds of all your legs together to get the combined payout multiplier. No need to convert legs back and forth. For a deeper dive into how odds connect to expected value and bet sizing, see our guide to the best free tools for sports bettors.
Understanding odds conversion is most powerful when paired with expected value analysis. Once you know a bet's implied probability, you can compare it to your own probability estimate to determine whether you have an edge.
The process is straightforward: use this converter to find implied probability, estimate the true probability through research, then check whether your estimate exceeds the implied probability. If it does, use our EV Calculator to quantify exactly how much edge you have in percentage and dollar terms.
For sizing that bet correctly once you have confirmed positive expected value, use the Kelly Criterion Calculator, which tells you what fraction of your bankroll to wager based on your edge and the odds.
For positive American odds: divide by 100 and add 1. So +150 becomes (150/100) + 1 = 2.50. For negative American odds: divide 100 by the absolute value and add 1. So -110 becomes (100/110) + 1 = 1.909.
Decimal odds are the easiest for calculations. Implied probability is simply 1 divided by the decimal odds. Parlay payouts are the product of all decimal odds. Expected value calculations are also simpler in decimal format. Convert to decimal first whenever you need to do serious math.
No. US books use American odds. Most European and Australian books use decimal. UK books and horse racing use fractional. International sharp books like Pinnacle use decimal. If you bet at multiple books internationally, you will encounter all three formats regularly.
A fair line removes the sportsbook's margin so both sides sum to exactly 100% probability. For a balanced two-sided market at -110/-110, each side's implied probability is 52.38%, totaling 104.76%. The no-vig probability for each side is 52.38% / 104.76% = 50.00%. The no-vig American equivalent for 50% is +100.
Convert to decimal first (numerator/denominator + 1), then convert from decimal to American. So 5/2 becomes (5/2) + 1 = 3.50 decimal, then (3.50 - 1) x 100 = +250 American.
Because sportsbooks build a margin into their lines, called the vig or juice. At standard -110/-110 pricing, each side implies 52.38%, totaling 104.76%. The extra 4.76% represents the book's long-run edge. To find true market probabilities, you need to normalize each side by dividing by the total overround.