Free tools
Free sports betting calculators.
Odds conversion, parlay payouts, Kelly bet sizing, value and arbitrage. Free, no sign-up. Every converter reads prediction-market prices too, for Kalshi and Polymarket.
See where the prediction markets disagree with the books on the prediction-market board.
Research
Odds & payouts
Odds converter →
Convert between American, decimal, and fractional odds, plus Kalshi and Polymarket prediction-market prices.
Parlay calculator →
Enter each leg's American odds and your stake to see combined parlay odds, total payout, and the real win probability.
Hedge calculator →
Lock in guaranteed profit on an open bet: enter your original odds and stake plus the current price on the other side to get the exact hedge stake and the profit you keep either way.
Bonus bet value →
See what a sportsbook bonus bet or free bet is really worth in cash.
Probability & value
Implied probability →
Turn any American odds or a Kalshi/Polymarket price into the implied win probability, then compare it to your own estimate to find betting value.
Line shopping →
See how much profit you leave on the table by not betting the best available number.
No-vig calculator →
Strip the sportsbook's vig out of any two-way line to get the fair odds and the true, de-juiced win probability for each side.
Hold calculator →
Calculate the hold percentage on any two-way market to see how much margin the sportsbook is charging.
Arbitrage calculator →
Find guaranteed-profit arbitrage between two books, with the exact stake to put on each side and your locked-in return.
Expected value →
Turn odds, your win probability, and stake into the expected value of a bet in dollars and percent.
Break-even win rate →
Find the win rate you need to break even at any price, then project a season's profit from your real hit rate.