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Parlay calculator with true odds

Add each leg’s odds. The calculator multiplies them into the parlay price and payout, and, if you add fair probabilities, the true hit rate and EV.

Parlay calculator illustration

How parlay odds work

For legs that do not depend on each other, the parlay’s decimal odds are the product of the legs’ decimal odds, and its true chance is the product of the legs’ true chances.

parlay odds D = d₁ × d₂ × …; true chance P = p₁ × p₂ × …; EV = D × P − 1

The book’s margin compounds the same way. Three legs at −110 pay +596, but if each is a true coin flip the fair price is +700. The parlay carries about three times the vig of a single bet.

Same-game legs

Legs from one game move together: a quarterback’s passing yards and his team covering are not independent. Multiplying them understates or overstates the chance. The Arbs parlay builder simulates correlated legs instead of multiplying them.

Worked example

Worked example: Three legs at −110 each

  1. Decimal per leg: 1.909, so the parlay is 1.909³ = 6.96, or +596
  2. If each leg is a coin flip: true chance 0.5³ = 12.5%, fair price +700
  3. EV: 0.125 × 6.96 − 1

−13%: nearly three times the −4.5% of a single −110 bet.

Frequently asked questions

How are parlay odds calculated?

Convert each leg to decimal odds and multiply them. Three legs at 1.91 make 1.91 × 1.91 × 1.91 = 6.96, so a $100 parlay returns $696.

Are parlays ever +EV?

Only when the legs are +EV on their own, or when the book prices correlated legs as if they were independent. Otherwise the vig compounds with every leg. The parlay guide goes through both cases.

Why is my parlay payout lower than the calculator?

Some books shade parlay and same-game parlay prices below the product of the legs. Compare the price they offer with the product here to see how much extra margin they took.

Read the guide: Are parlays ever +EV? Correlation explained

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