Free Sports Betting & Odds Tools
7 interactive calculators and converters for odds, probability, expected value, margin analysis and arbitrage. Used by 5,000+ traders, developers and analysts every month.
Odds Converter — Decimal ↔ Fractional ↔ American
Instantly convert between decimal, fractional and American odds formats. Used by sportsbooks, traders and developers integrating odds data.
One Number. Four Faces.
Decimal, fractional, American, implied probability — same odds, different formats. Watch them stay in sync, or try your own below.
All conversions calculated in real-time — try your own odds above ↑
Implied Probability Calculator
Convert odds into implied win probability. Essential for identifying value bets and understanding market sentiment.
Expected Value (EV) Calculator
Determine whether a bet has positive expected value over time. A core metric for professional traders and sharp bettors.
Margin (Overround) Calculator
Calculate the bookmaker's built-in margin across a two-outcome market. Lower margins mean better value for bettors.
Payout Calculator
Calculate your total return including stake and profit for any bet amount and odds format.
Arbitrage Calculator
Detect guaranteed profit opportunities when odds across bookmakers create an arbitrage window.
Overround Calculator
Calculate the total bookmaker overround across a full market with any number of outcomes.
Complete Tool Suite
Every tool you need for odds analysis, betting strategy, and market evaluation.
Odds Converter
Convert between decimal, fractional and American odds instantly.
Implied Probability
Calculate win probability from any odds format.
Expected Value (EV)
Determine if a bet has positive expected value.
Margin Calculator
See the bookmaker's built-in margin across a market.
Payout Calculator
Calculate total return, profit and ROI for any bet.
Arbitrage Calculator
Detect guaranteed profit opportunities across books.
Overround Calculator
Calculate the total market overround for any number of outcomes.
Kelly Criterion
Optimal bet sizing based on your edge and bankroll.
Related Pages
Explore more resources for odds analysis and sports data.
Glossary
Plain-English definitions for odds, xG, implied probability and more.
Odds API
Pre-match and live odds normalized across 50+ sportsbooks.
Guides
Practical walkthroughs for building with the Orbistats API.
Documentation
Full endpoint reference and developer resources.
Common Questions About Our Tools
Quick answers to the most frequently asked questions about using these free betting tools.
How do I convert decimal odds to American odds?
For decimal odds > 2.00: (decimal - 1) × 100 = positive American odds. For decimal odds between 1.00 and 2.00: -100 / (decimal - 1) = negative American odds. Use our free Odds Converter tool above for instant conversion.
What is implied probability in sports betting?
Implied probability is the likelihood of an outcome as suggested by the odds. For decimal odds, it's 1 / decimal × 100. If odds are 2.00, the implied probability is 50%. When implied probabilities across all outcomes sum to over 100%, that extra percentage is the bookmaker's margin (overround).
How do I calculate expected value (EV) in betting?
Expected value = (probability of win × amount won per bet) - (probability of loss × amount lost per bet). A positive EV means the bet has mathematical value over time. Use our EV Calculator to quickly determine if a bet is worthwhile.
What is arbitrage betting and how do I find it?
Arbitrage betting occurs when odds across different bookmakers create a situation where you can bet on all outcomes and guarantee a profit. Use our Arbitrage Calculator to check if a set of odds offers an arbitrage opportunity.
Are these betting tools free to use?
Yes, all tools on this page are completely free to use with no signup or registration required. If you need to integrate these calculations into your own application, check out our Odds API for programmatic access.
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