The math doesn't care what platform you're on.
Free calculators and guides for anyone who trades outcomes.Free calculators and guides for anyone who trades outcomes. Sportsbooks, Kalshi, Polymarket, or wherever the edge is.
Popular
Prediction Markets
Kalshi, Polymarket, and beyond — fee analysis, EV sizing, liquidity, and portfolio risk.
Market Converter
Convert between sportsbook odds and prediction market prices
Fee Calculator
See how Polymarket and Kalshi fees affect your EV
Break-Even
See how often you need to win after platform fees
PM EV Calculator
Expected value and Kelly sizing for prediction market contracts
Multi-Outcome
Find mispriced outcomes in multi-outcome markets
Liquidity
Simulate order book slippage before placing large orders
Position Risk
See how correlated positions amplify your portfolio risk
Cross-Platform
Compare odds across sportsbooks and prediction markets. Find arbs that survive fees.
Sports Betting
De-vig any line, size your bets, and quantify your edge with real math.
De-Vig Calculator
Remove vig from bookmaker odds — 7 methods compared side-by-side
EV Calculator
Find +EV bets by comparing rec book odds against sharp lines
Odds Converter
Convert between American, Decimal, Fractional and Implied Probability
Kelly Criterion
Calculate optimal bet size based on your edge, odds, and bankroll
Parlay Calculator
Find the true fair odds of your parlay and see the hidden vig
Hold Calculator
See how much vig the sportsbook is charging on any market
What's My Edge?
Test if your betting record shows real skill or just luck
Latest from the blog
Quantitative guides across sports betting and prediction markets.
Sportsbook vs Prediction Market Arbitrage: How to Find and Execute Cross-Platform Arbs
De-Vig Calculator: How to Strip the Margin From Any Betting Line
Line Movement: How to Read, Interpret, and Profit From Shifting Odds
Frequently asked questions
Everything you need to know about Market Math and outcome trading tools.
- What is Market Math? +
- Market Math is a free suite of quantitative calculators and guides built for anyone who trades outcomes — whether on sportsbooks like DraftKings and FanDuel, or prediction markets like Kalshi and Polymarket. Every tool runs entirely in your browser with no signup required.
- Are the calculators really free? +
- Yes. Every calculator on Market Math is 100% free, with no account required and no usage limits. The tools run entirely in your browser — your data never leaves your device.
- What does "de-vigging" mean? +
- De-vigging (or removing the vig) is the process of stripping a sportsbook's built-in margin from their posted odds to reveal the true implied probabilities. Sportsbooks inflate their odds so the implied probabilities sum to more than 100%. Our de-vig calculator uses multiple methods — including Multiplicative, Power, Shin, and Additive — to back out fair odds.
- What are prediction markets? +
- Prediction markets are exchanges where you buy and sell contracts on real-world outcomes — elections, economic data, weather events, and more. Platforms like Kalshi and Polymarket let you trade these contracts at prices that reflect the crowd's implied probability of each outcome.
- How is Market Math different from other betting calculators? +
- Most betting calculators only handle sportsbook odds. Market Math is built for the full spectrum of outcome trading — sportsbooks and prediction markets. Our tools account for prediction market fees, contract structures, and cross-platform arbitrage opportunities that generic calculators ignore.
- Can I embed these calculators on my own site? +
- Yes. Every calculator has an embeddable version. You can use a simple iframe to add any Market Math calculator to your website, blog, or app. The embeds automatically resize to fit their container.