Add legs to a parlay and instantly see the expected value, true win probability, and comparison to single bets.
A parlay is a multi-leg bet where all legs must win for you to collect. Your winnings from one leg roll into the next, creating multiplied odds.
Parlays look attractive (10:1 odds on a 2-leg parlay), but they multiply the vig (house edge) across all legs. Most parlays have deeply negative EV.
Book odds are what the sportsbook offers (includes vig). Fair odds remove the vig and represent true probability. Use fair odds to calculate true EV.
Parlays only have positive EV when your individual legs have very high EV. Even then, combining them can reduce total EV due to vig multiplication.
Always compare parlay EV to the combined EV of betting those legs individually. Usually singles are superior because vig is lower on single bets.
Parlay EV is calculated by finding the true win probability (all legs hit) and comparing it to the odds offered by the book.
Yes, but rarely. A parlay has positive EV only if your individual legs have very high EV (+5% or more each). Even then, combining them often reduces total EV due to vig multiplication.
Because vig is multiplicative. On a 2-leg parlay, you pay vig twice (once per leg), and that vig gets multiplied in the final payout. Singles avoid this compounding.
Fair odds (no-vig odds) are optional. If you know the true probability of a leg, convert it to fair odds and enter it. The calculator will use fair odds to compute true win probability.
Only if the parlay EV is positive AND higher than the singles EV. This is uncommon. Most recreational parlay bets are negative EV traps.
This calculator assumes legs are independent. If legs are correlated (e.g., both teams in the same game), the true win probability is different, and you should not use parlays.
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