Odds Converter
Convert between American, Decimal, and Fractional betting odds formats instantly
Convert Odds
Enter odds in any format to convert
Quick Examples
How to Convert Odds
To convert American odds to decimal: for positive odds, divide by 100 and add 1 (e.g., +150 = 2.50); for negative odds, divide 100 by the absolute value and add 1 (e.g., -200 = 1.50). To convert decimal to American: if decimal > 2, American = (decimal - 1) × 100; if decimal < 2, American = -100 / (decimal - 1).
Key Facts
- ✓American odds of +100 equal decimal 2.00 and fractional 1/1 (evens)
- ✓Standard betting line -110 equals 1.91 decimal (52.4% implied probability)
- ✓Decimal odds show your total return per unit staked (stake + profit)
- ✓Fractional odds show profit relative to stake (e.g., 3/1 means $3 profit per $1 staked)
- ✓Implied probability = 1 / decimal odds (expressed as percentage)
- ✓UK/Ireland use fractional odds, Europe/Australia use decimal, US uses American
Frequently Asked Questions
What are American odds?▼
American odds (also called moneyline odds) use positive and negative numbers. Positive odds (+150) show how much profit you make on a $100 bet. Negative odds (-200) show how much you need to bet to win $100. They're the standard format in US sportsbooks.
How do fractional odds work?▼
Fractional odds (e.g., 3/1, 1/2) show profit relative to stake. The first number is potential profit, the second is your stake. So 3/1 means you win $3 for every $1 bet. "Odds on" favorites show fractions less than 1 (like 1/2), meaning you risk more than you can win.
Why do sportsbooks use different odds formats?▼
Different regions have historical preferences. American odds developed in US horse racing, fractional odds are traditional in UK/Ireland, and decimal odds became standard in Europe and Australia because they're easiest to calculate total returns. Most modern sportsbooks let you choose your preferred format.
What is implied probability?▼
Implied probability is the win probability that betting odds suggest. It's calculated as 1 / decimal odds. For -200 American (1.50 decimal), implied probability is 1/1.50 = 66.7%. This tells you what win rate you need to break even at those odds.
Which odds format is best?▼
Decimal odds are best for quick calculations since you just multiply by stake to get total return. However, use whatever format your sportsbook displays to avoid conversion errors. Our converter helps you switch between formats instantly.
How this works
Calculations follow the published mathematics of the game — combinatorics for cards, probability theory for dice, and expected-value accounting for wagers. Results are verified against independent references (primarily Wizard of Odds). No calculation here is an opinion or recommendation; it is arithmetic applied to the rules of the game.
What this tool can’t do
When to consult a professional
This tool computes probability and expected value. It is not a betting system and cannot predict the outcome of any individual wager. If gambling is causing problems for you or someone you know, call the National Problem Gambling Helpline at 1-800-GAMBLER.
Sources
- [1]Wizard of Odds — Michael Shackleford, ASAIndustrywizardofodds.comAccessed Apr 21, 2026
Actuary; widely cited casino-game probability reference. Used for house-edge and EV verification.
- [2]National Council on Problem GamblingOfficial sourcencpgambling.orgAccessed Apr 21, 2026
Responsible-gambling guidance and 1-800-GAMBLER helpline.
Joseph OrdunaFounder & Software Engineer
Full-stack software engineer specializing in embedded systems, web architecture, and AI/ML. Founder of Practical Web Tools. Built the gesture-controlled drone IP acquired by KD Interactive (Aura Drone, sold on Amazon).