One parlay is easy to analyze. Your long-term process is harder.
EVRAI tracks your bets, closing-line value, expected value, bankroll, execution quality, and performance over time.
Track your bets freeHow parlay odds are calculated
Every leg is converted to decimal odds and multiplied together. Decimal odds represent total return per unit staked, so multiplying them compounds the return of each leg.
The combined decimal price is converted back to American odds for display, and the payout is simply stake × combined decimal odds.
Why parlay probability drops as legs are added
Under an independence assumption, the probability that every leg wins is the product of the individual probabilities. Three legs at 60% each land together only 21.6% of the time. Payout rises, but the chance of full success falls faster than most people expect.
Why sportsbook margin can compound
Each leg price already contains the sportsbook's margin. Multiplying marginal prices multiplies whatever margin they contain, which is why parlay break-even probabilities are usually well above the joint probability implied by fair prices. For same-game parlays the picture is more complicated: sportsbooks reprice the combination, and the difference from the independent benchmark can reflect correlation, margin, rounding, or market rules together.
What expected value means in a parlay
Expected value compares your own probability estimate with the price you are offered. If you supply a probability for each leg, this calculator multiplies them into an independent-leg modeled probability and compares it with the break-even probability of the quoted price.
The result is only as good as your estimates. It describes your assumptions, not an objective truth about the market.
What makes same-game parlays different
Legs from the same event are usually correlated. A quarterback throwing for 300 yards and his top receiver going over 80 yards are not independent events. Multiplying their marginal probabilities can badly over- or under-state the real joint probability, and marginal prices alone cannot reveal the correlation. That is why this tool flags same-event legs and labels every joint figure as an independence assumption rather than a fair same-game price.
Parlay vs straight bets
A parlay pays more per dollar risked, succeeds less often, carries far higher variance, and compounds price margin across every leg. Straight bets settle independently, so a single loss does not void the rest. Which structure fits depends on your own estimates and bankroll rules — see bankroll management and Kelly sizing.
Frequently asked questions
How are parlay odds calculated?
Convert each leg to decimal odds, multiply them, and convert the product back to your preferred format. Decimal 1.91 × 2.10 = 4.011, or about +301 in American odds.
How do I calculate a parlay payout?
Multiply your stake by the combined decimal odds. Profit is that payout minus the stake.
What does +600 pay on a $100 bet?
+600 is 7.00 in decimal odds, so a $100 stake returns $700 total — $600 profit.
Why are same-game parlay odds different?
Sportsbooks reprice correlated combinations instead of multiplying marginal prices. The Price Audit section above shows the size of that adjustment without attributing it to a single cause.
What happens if one leg pushes or voids?
Most sportsbooks drop the pushed leg and recalculate the parlay at the remaining legs' price, but settlement rules vary by sportsbook and by market. Check your book's rules.
Can a parlay be +EV?
It can, if your probability estimates on each leg are better than the prices you are taking, or if correlation works in your favour on a same-game combination. Compounded margin makes that harder than on straight bets.
Why does adding one leg change the payout so much?
Because prices multiply rather than add. The “What changed?” panel shows the probability cost next to the payout gain for the leg you added.
Does a parlay calculator account for correlation?
This one flags it rather than pretending to price it. When you mark legs as belonging to the same event, the tool warns that the independent calculation may not represent the actual joint probability.
Related tools and reading
Pair this with the CLV calculator, expected value guide, and positive EV betting strategy.