Trade smarter with math on your side. Calculate expected values, optimize bet sizes, convert odds, and find arbitrage opportunities.
Start Calculating →Professional tools to help you analyze markets, calculate expected value, and make smarter trading decisions.
Calculate expected value to determine if a bet is +EV or -EV based on your probability estimate
Determine the optimal bet size to maximize long-term growth while managing risk
Convert between market prices, decimal odds, and implied probabilities
Calculate the minimum win rate required to break even at different market prices
Check if there's a risk-free arbitrage opportunity between YES and NO prices on a market
Lock in guaranteed profit by hedging your position when odds have moved in your favor
The Expected Value calculator helps you determine whether a bet offers positive or negative expected value based on your probability estimate versus the market price. EV is the cornerstone of profitable betting — a positive EV (+EV) bet means that, on average over many repetitions, you'll profit. The calculator shows your "edge" as the difference between your estimated probability and the market's implied probability.
The Kelly Criterion calculates the mathematically optimal bet size to maximize long-term bankroll growth while minimizing risk of ruin. Developed by John Kelly at Bell Labs in 1956, this formula considers both your edge and the odds offered. Most professional bettors use "Half Kelly" or "Quarter Kelly" to reduce variance and account for uncertainty in their probability estimates.
This implied probability converter tool converts between different odds formats used across prediction markets and sportsbooks. Market prices (in cents) directly represent implied probability on platforms like Polymarket and PredictIt. Decimal odds are common in Europe and Asia, while American odds (+/-) are standard in US sportsbooks. Understanding these conversions helps you quickly compare odds across platforms.
This break-even win rate calculator determines the minimum win rate you need to break even given your entry price. For example, if you buy YES shares at $0.65, you need to win more than 65% of similar bets to profit long-term. This helps calibrate whether your actual historical accuracy supports the prices you're paying and identify when you might be overconfident.
The Hedging Calculator helps you lock in guaranteed profits when market odds move in your favor. If you bought YES shares at $0.40 and the opposite (NO) shares are now available at $0.35, you can hedge your position by buying NO shares to guarantee profit regardless of the outcome. This tool calculates exactly how much to invest in the hedge to maximize or equalize your profit across both scenarios. It's particularly useful for locking in winnings on futures bets or when you want to reduce risk exposure.
The Arbitrage Detector identifies risk-free profit opportunities when YES and NO prices don't add up to $1.00. If you can buy both YES and NO shares for less than $1 combined, you're guaranteed a profit regardless of the outcome. These opportunities are rare in efficient markets but can occur during high volatility, across different platforms, or in illiquid markets.
This Prediction Calculator is designed for prediction market traders, sports bettors, and anyone looking to make more informed betting decisions. It provides essential tools for calculating Expected Value (EV), determining optimal position sizes using the Kelly Criterion, converting between odds formats, and detecting arbitrage opportunities.
The calculator uses industry-standard formulas including the Kelly formula for bet sizing, probability-weighted expected value calculations, and break-even analysis. Whether you're trading on Polymarket, PredictIt, Kalshi, or traditional sportsbooks, these tools help you make mathematically sound decisions.
Stock market calculations including position sizing, risk management, profit/loss scenarios, and dividend reinvestment analysis for equity investors.
Digital asset calculations including portfolio tracking, profit/loss analysis, DCA strategies, and crypto-to-crypto conversions across Bitcoin, Ethereum, and other major cryptocurrencies.
Important: This calculator is provided for informational and educational purposes only and should not be considered as financial or betting advice. Prediction markets and sports betting involve significant risks, and you may lose your entire investment.
The calculations assume your probability estimates are accurate, which is rarely the case in practice. The Kelly Criterion, while mathematically optimal, can lead to high variance and significant drawdowns. Past performance does not guarantee future results.
Always bet responsibly and only risk money you can afford to lose. Verify all calculations independently before making any betting decisions. Check that prediction markets and sports betting are legal in your jurisdiction. We may participate in affiliate programs and receive compensation for referrals to third-party platforms.
PredictionCalculator