Betting calculators
Five free calculators for the arithmetic behind a sportsbook price: converting odds between formats, the probability a price implies, removing the sportsbook’s margin, the expected value of a bet at your own probability estimate, and a parlay’s combined odds. Each page shows its formulas and worked examples, and works without an account.
Odds converter
American, decimal and fractional odds are three ways to write the same price. The odds converter turns any of them into the other two and shows the implied probability, with a table of common prices from −1,000 to +1,000.
Implied probability calculator
A price implies a probability: 1 divided by the decimal odds, so −110 implies 52.38%. The implied probability calculator works it out for any format, and in reverse gives the fair odds (no margin) for a probability you enter.
No-vig calculator
A sportsbook’s prices for all outcomes of a market add up to more than 100%; the excess is its margin. The no-vig calculator takes one sportsbook’s prices for a two-way or three-way market and shows the overround, the hold and the no-vig probabilities and fair odds by the multiplicative method, with how other methods differ.
Expected value calculator
The expected value calculator shows the average profit or loss per bet at a price, a stake and a win probability that you supply, plus the break-even probability. The probability is your own estimate: the calculator does not know the true chance of any result, and EV is a long-run average, not a promise about one bet.
Parlay calculator
The parlay calculator multiplies two to six legs into combined odds, a payout and an implied probability. That probability assumes independent legs; legs in the same game are often related, and the page explains which way that pushes the numbers.
How the calculators work
- Every calculation goes through decimal odds and uses unrounded values; only the displayed results are rounded (American odds to whole numbers, decimal odds to two or three places, probabilities to two decimal places).
- Inputs that cannot be a price, such as American odds between −100 and +100 or decimal odds of 1.00 or less, get a message instead of a result.
- The live forms run in your browser. Nothing you enter is sent to StatsNext or stored.
- Without JavaScript, every page still shows its formulas and worked examples.
Arithmetic, not advice
These calculators do arithmetic on the numbers you enter. They do not know the true chance of any result, they do not predict outcomes, and using them does not make betting profitable. Betting involves financial risk, and no research or model makes gambling safe or removes that risk.
StatsNext is for people 18 and older. Being 18 or older does not mean sports betting is legal for you: follow the laws and legal gambling age requirements where you live. Never wager money you cannot afford to lose, and do not chase losses. If gambling stops feeling like it is within your limits, free and confidential help is available 24/7 from the National Problem Gambling Helpline: 1-800-MY-RESET (1-800-697-3738). More resources are on the Responsible Gambling page.
StatsNext is a research platform, not a sportsbook; it does not accept wagers or guarantee results (Research Disclaimer, Responsible Gambling).
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Odds converter
American, decimal and fractional odds, with implied probability.
Implied probability calculator
The probability a price implies, and fair odds for a probability.
No-vig calculator
Remove the margin from a 2-way or 3-way market: hold and fair odds.
Expected value calculator
EV of a bet from the odds, your stake and your own probability estimate.
Parlay calculator
Combined odds, payout and implied probability of a parlay.
Sportsbook odds comparison
How StatsNext compares prices across sportsbooks and what each probability means.