A parlay (also called an accumulator or acca) combines multiple individual bets into one wager. Every leg must win for the parlay to pay out. In exchange for this increased risk, the payout multiplies — each leg's decimal odds are multiplied together to produce the combined odds.
Why parlays are high risk: If any single leg loses, the entire wager is lost. A 4-leg parlay where each leg has a 60% chance of winning has only a 12.96% chance of hitting (0.6 × 0.6 × 0.6 × 0.6). The more legs you add, the smaller that combined probability becomes.
The house edge compounds with every leg. Sportsbooks price each leg with a built-in margin (the "vig"). When you multiply those margins together across multiple legs, the effective edge against you grows substantially. A 5% vig on each of 5 legs compounds to a ~23% edge against the bettor on the parlay as a whole.
Implied probability vs. true probability: The implied probability shown above is derived from the odds and includes the sportsbook margin. Your actual probability of winning is lower than the quoted odds imply. For a parlay to be +EV (positive expected value), your true estimated win probability must exceed the break-even rate shown in the results.
When parlays can make sense: Correlated parlays — where one outcome makes another more likely — can reduce the house edge and are sometimes restricted by books for this reason. Parlays also make sense as small fun bets when the goal is large upside with limited downside, rather than long-term profit.
Note: This calculator uses exact math based on the odds entered. It does not account for correlated outcomes, pushed legs, or sportsbook-specific parlay rules.
