Parlay Calculator & Builder
Add legs by their moneyline odds and watch the combined odds, payout, and true win probability update live. See exactly how the sportsbook edge compounds with every leg you stack.
Parlay Calculator
Combine legs to see true odds, payout, and how the house edge compounds.
Legs
2
Parlay odds
+377
Payout
$238.64
Implied win %
21.0%
Every leg you add multiplies the potential payout — but also multiplies the house edge, so the combined implied probability falls fast. Parlays are high-variance and statistically favor the sportsbook. Bet responsibly.
How parlay odds are calculated
A parlay only pays if every leg wins, so the legs multiply. Convert each leg's American odds to decimal, multiply them for the combined decimal odds, then convert back. The true probability is the product of each leg's implied probability — and that's exactly where the sportsbook edge compounds against you.
Worked example
Take a two-leg parlay: one leg at −110 (decimal 1.909) and one at +150 (decimal 2.500).
- 1. Combined decimal: 1.909 × 2.500 = 4.773 → +377 American.
- 2. A $50 stake returns $238.64 profit if both hit.
- 3. True odds of hitting: 52.4% × 40.0% = 21.0% — much slimmer than either leg alone.
That gap between the payout and the true probability is the parlay tax. Size any parlay stake conservatively with our Kelly bankroll calculator, and seed your legs above from today's highest-confidence AI picks.
Frequently asked questions
- How is a parlay payout calculated?
- Each leg is converted to decimal odds, and the decimal odds of every leg are multiplied together. Multiplying that combined figure by your stake gives the total return, and subtracting the stake gives the profit.
- Why do parlays favor the sportsbook?
- The bookmaker margin baked into each leg compounds with every leg you add. This calculator shows the true combined probability versus the probability implied by the payout, so you can see exactly how much edge you are giving up.
- Does a longer parlay mean better value?
- Bigger payouts come with disproportionately lower win probability. More legs multiply the sportsbook hold, so unless each individual leg carries genuine positive expected value, adding legs lowers your long-term return.