Calculators

Free calculators

SmartStake publishes a set of standalone calculators at /tools that are free to use without an account. They cover the core calculations behind sports betting math — from checking whether two lines form an arbitrage to converting prediction market prices into sportsbook odds. Each calculator is a single-purpose tool: enter your numbers, get an answer. They do not scan live odds or connect to your bet tracker.

The calculators are organised below by use case.

Arbitrage

• Arbitrage Calculator — enter the odds for two opposite sides of the same event and your stake on one side; the calculator outputs the hedge stake for the other side and tells you whether the combined implied probabilities fall below 100%. Useful for verifying a candidate arb before placing both legs. See Finding arbitrage for the live scanner.

• Low Hold Calculator — enter odds for both sides of a market to compute the combined hold (vig) percentage. Lower hold means less margin surrendered to the books; lines under roughly 2–3% are worth considering when working through a promotion. A negative combined hold is a candidate arbitrage at the time of measurement.

Positive EV

• Expected Value Calculator — enter your wager amount, the odds, and your estimated win probability; the calculator returns the theoretical expected value of the bet. Useful for spot-checking a specific line before placing it. Background on the concept is in Expected value betting.

• Devigging Calculator — enter both sides of a two-outcome market and the calculator strips the book's margin to produce the no-vig fair odds and implied probability for each side. Supports the same devigging methods available in the main tools (multiplicative, power, and others). For a deeper explanation of why the method choice matters see Devigging & fair value and No-vig fair odds.

• Kelly Calculator — enter the odds, your estimated win probability, and your bankroll; the calculator returns the full-Kelly fraction and, optionally, a fractional-Kelly stake based on a multiplier you set. Many experienced bettors use quarter-Kelly (0.25×) or lower to reduce variance. The concept is covered in Kelly criterion & staking.

Promo conversion

• Freebet Calculator — for sportsbook "free bet" promotions where the stake is not returned on a win. Enter your free bet amount and odds on one side and the hedge odds on the other; the calculator outputs the recommended hedge stake and the estimated net return.

• "No Sweat Bet" Calculator — for promotions that refund your stake as a free bet credit if you lose (sometimes marketed as "risk-free" bets, though they are not). Uses a different two-step hedging calculation than a standard free bet, which is why it has a separate calculator.

• Low Hold Calculator — also relevant here: finding a low-hold line between two books before placing your promo bet minimises the spread you give up to sportsbook margins. See the Arbitrage section above for details.

General

• Odds Converter — converts a line entered in any format — American (moneyline), decimal, or fractional — into all four formats simultaneously, including implied probability. Useful when comparing odds across books that display different formats.

• Prediction Market Converter — converts Polymarket and Kalshi contract prices (expressed as cents, i.e. implied probability × 100) into American, decimal, and fractional odds. Useful for comparing a prediction market price directly against a sportsbook line on the same event.