The Reference
for Odds
Real-time odds aggregation across prediction markets and sportsbooks. Track 12,000+ markets, 27M+ price data points, and the whale trades moving the lines.
Calculators & Analysis
Odds Converter
Convert between American, Decimal, and Fractional odds formats instantly
Parlay Calculator
Calculate parlay odds, payouts, and implied probabilities for multi-leg bets
EV Calculator
Find expected value on any bet to identify profitable opportunities
Vig Calculator
Calculate the bookmaker's margin and find the true odds on any market
Hedge Calculator
Calculate optimal hedge positions to lock in guaranteed profit
Kelly Calculator
Determine optimal bet sizing using the Kelly Criterion formula
Arb Calculator
Find and calculate arbitrage opportunities across sportsbooks
Fee Calculator
Compare trading fees across prediction market platforms
Market Platforms
Education & Guides
Prediction Markets
Prediction Market Accuracy Report 2026: Calibration by Platform
OddsReference calibration analysis: how accurate are Polymarket, Kalshi, and Metaculus? Calibration curves, Brier scores, and category breakdown across platforms.
What Is Calibration in Forecasting? A Data-Driven Explainer
A forecaster is calibrated when their 70% predictions come true 70% of the time. How calibration is measured, Brier scores explained, and which platforms score best.
Crypto Prediction Markets: Bitcoin, Ethereum, and Altcoin Odds
Prediction market odds on Bitcoin price, Ethereum milestones, and crypto regulatory events. Live data across Polymarket and Kalshi's crypto event contracts.
Economics Prediction Markets: Fed Rate, Inflation, and GDP Odds
Prediction market odds on Federal Reserve rate decisions, CPI inflation, GDP growth, and recession probability. Live data from Kalshi economic event contracts.
Politics Prediction Markets: Live Odds and Forecasts
Live prediction market odds on elections, legislation, and geopolitical events. What markets say about major political outcomes across Polymarket, Kalshi, Metaculus.
Sports Betting
How to Find Arbitrage Opportunities in Sports Betting
Arbitrage betting exploits odds differences between sportsbooks for guaranteed profit regardless of outcome. How arbs work, how to find them, risks, and tools.
Arbitrage Calculator: Calculate Sports Betting Arb Opportunities
Free arb calculator: find guaranteed profit opportunities between sportsbooks. Enter odds from two books to calculate stake sizes and guaranteed profit amount.
Bankroll Management for Sports Bettors: A Practical Guide
Bankroll management determines how much to bet per play. Flat betting, Kelly criterion, and percentage staking explained with worked examples and common mistakes.
Expected Value Calculator: Calculate EV for Any Bet or Trade
Free EV calculator for sports bets and prediction market trades. Enter probability and odds to calculate expected value and determine if a bet is profitable.
What Is Expected Value (EV) in Sports Betting?
Expected value measures whether a bet is profitable long-term. Positive EV bets make money over time; negative EV bets lose. Formula, examples, and calculation guide.