Betting calculators

How the six tools fit together

Every tool on this page works on the same raw material: a price, and what that price implies. The odds converter translates between American, decimal and fractional formats so the rest of the math has one language to work in. The no-vig calculator strips the sportsbook's margin out of a market to reveal the fair line underneath, and our guide to vig shows what that margin quietly costs over a season.

From there it becomes a question of value and size. The expected value calculator weighs a price against the probability you think is right; the theory behind that number lives in our positive EV guide. The Kelly calculator turns an edge into a stake scaled to your bankroll, explained in the Kelly criterion guide. The parlay calculator multiplies legs into one combined price so you can see what the book is really paying for the bundle, and the parlay betting guide covers when that trade is worth making.

The arbitrage calculator ties the set together. When two books price the same market far enough apart, backing both sides returns a profit whichever way the game goes, a situation known as a surebet. The calculator splits your stake so the return is identical on either outcome. Arbitrage betting 101 walks through finding and placing these, and line shopping is the habit that surfaces them in the first place.