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Yes No Odds

Parlay Calculator

American: -110 or +150. Decimal: 1.91. Fractional: 10/11.

Total payout if every leg wins $91.12

Profit
$81.12
Combined decimal odds
9.1116
Combined American odds
+811
Implied probability (with vig)
10.98%

Legs as decimal odds: 1.9091 × 1.9091 × 2.5000 = 9.1116

Payout and profit are rounded to the cent after multiplying. Implied probability is the product of each leg's implied probability at the posted price, so it includes the sportsbook's vig and overstates the true chance. Informational only; not betting advice.

Sources: STN Sports house rules (Station Casinos, Nevada) — parlay payout is the product of each leg's payout conversion times the stake; DraftKings Massachusetts house rules (Mass. Gaming Commission) — parlay definition and void-leg recalculation; FanDuel Massachusetts house rules — moneyline definitions behind the American-to-decimal conversion; Mathematics of bookmaking — multiplication rule and its independence assumption.

How It Works

A parlay pays only if every leg wins, and its price is the product of the legs’ prices. Nevada house rules state it directly: parlay payouts are computed by multiplying the payout conversion of each team by the amount wagered. Massachusetts-approved house rules say the same thing in fewer words: parlay odds are calculated from the prices of the individual selections.

The calculator first turns every leg into decimal odds, the total return per $1 staked. A negative American price such as -110 means you risk $110 to win $100, so the decimal is 1 + 100/110 = 1.9091. A positive price such as +150 wins $150 per $100, so the decimal is 1 + 150/100 = 2.50. Fractional odds a/b become 1 + a/b. Multiply the decimals together, then multiply by the stake for the payout; profit is payout minus stake. Payout is rounded to the cent at the end, not per leg.

Implied probability is 1 divided by the combined decimal odds, which equals the product of each leg’s implied probability. Because every leg is priced with the sportsbook’s vig, this figure overstates the real chance the parlay wins; the odds converter shows how much vig sits in a single price. The multiplication rule also assumes the legs are independent, which is why books restrict correlated parlays.

Prices on this site are read as probabilities, not recommendations. This tool is informational only.

Worked Example

Three legs at -110, -110 and +150 for a $10 stake. The decimals are 1.9091, 1.9091 and 2.5000; their product is 9.1116, which is +811 in American terms. Payout: $10 × 9.1116 = $91.12, so profit is $81.12. Implied probability: 52.38% × 52.38% × 40% = 10.98%.

FAQ

Why are American odds converted before multiplying?

American prices are quoted against $100 in two different directions, so they cannot be multiplied as written. Decimal odds are a plain multiplier on the stake, which is what the house rules multiply.

What happens if one leg pushes or is voided?

House rules drop that selection and recalculate the parlay from the remaining legs, which is the same as treating its odds as 1.00. In this tool, lower the number of legs and remove the pushed selection.

Does the implied probability include the vig?

Yes. It is built from posted prices, each of which carries the book’s margin, so the true probability is lower than the figure shown. A two-leg -110 parlay shows 27.44%, while two fair coin flips would be 25%.

Why is the combined price better than any single leg?

The multiplier compounds, but so does the margin: the vig in each leg multiplies through too, so long parlays carry a larger total house edge than the same legs bet singly.

Can I enter fractional or decimal legs?

Yes. Each leg has its own format selector; American, decimal and fractional legs can be mixed in one parlay.

Sources