Free betting math calculators
Six simple calculators for odds, payouts, parlays, margin, bonus rollover and tax forms. They run entirely in your browser, send nothing anywhere, and have no sportsbook links. They do arithmetic only: no picks, no predictions, no advice.
- Odds converter and implied probabilityAmerican, decimal and fractional, with the probability each price implies.
- Payout calculatorProfit and total return from odds and a wager, or the wager for a target profit.
- Parlay calculatorCombined odds, payout, push/void handling and the chance every leg hits.
- Vig and hold calculatorThe margin built into a set of prices and the margin-removed probabilities.
- Bonus rollover calculatorTotal wagering a bonus requires and an illustration of its cost.
- Form W-2G and withholding checkThe IRS reporting and 24% withholding tests for sports winnings.
The calculator code is tested against known values (for example, -110 converts to decimal 1.9091 and implies a 52.38% probability).