Parlay Probability Visualizer
See exactly how parlay probability drops exponentially as you add legs. Interactive chart reveals why sportsbooks love parlays, and why most bettors lose.
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Probability vs. Payout
Detailed Breakdown
| Legs | Win Prob | Chance of Losing | Payout Mult. | Expected Payout on $10 | EV per $1 | House Edge |
|---|---|---|---|---|---|---|
| 2 | 30.25% | -45.0% | 3.00x | $9.07 | $-0.0929 | 9.29% |
| 3 | 16.64% | -69.8% | 5.19x | $8.64 | $-0.1361 | 13.61% |
| 4 | 9.15% | -83.4% | 8.99x | $8.23 | $-0.1772 | 17.72% |
| 5 | 5.03% | -90.8% | 15.57x | $7.84 | $-0.2164 | 21.64% |
| 6 | 2.77% | -95.0% | 26.96x | $7.46 | $-0.2537 | 25.37% |
| 7 | 1.52% | -97.2% | 46.69x | $7.11 | $-0.2892 | 28.92% |
| 8 | 0.84% | -98.5% | 80.85x | $6.77 | $-0.3231 | 32.31% |
| 9 | 0.46% | -99.2% | 139.99x | $6.45 | $-0.3553 | 35.53% |
| 10 | 0.25% | -99.5% | 242.42x | $6.14 | $-0.3860 | 38.60% |
Leg-by-Leg Probability Drop
Each bar shows how probability cascades downward as legs are added. There is no weakest leg to find: under this model each added leg costs vig x (1 minus vig) of the remaining value, which is strictly smaller every time. The first leg you add is the most expensive one, and each one after costs less than the last.
10-Leg Parlay: The Illusion
A 10-leg parlay at 55% per leg pays 242x, but you only win 0.25% of the time. You would need to hit about 1 in every 395 attempts just to break even.
Net EV is Always Negative
Standard sportsbook odds include ~4.5% vig per leg. Each additional leg compounds the house edge, making longer parlays progressively worse bets. A 10-leg parlay has roughly 38.6% total house edge.
Parlay Types
Same-Game Parlays
- All legs from a single game
- Advantage: Legs can be correlated (e.g., team to win + over on total)
- Disadvantage: Sportsbooks adjust odds to account for correlation, often adding extra vig
- Correlation can work in your favor if the book underestimates it
- Typically limited to 4–8 legs by sportsbooks
Cross-Game Parlays
- Legs from different games/events
- Advantage: Legs are truly independent, no hidden correlation
- Disadvantage: No correlation edge to exploit; pure probability multiplication
- More legs available (up to 15+) but each compounds the house edge
- Higher variance, lower expected value
Correlated vs. Independent
- Independent: Outcomes do not affect each other (NBA game + NFL game)
- Correlated: Outcomes are linked (team points + game total in same game)
- Positive correlation means if one hits, the other is more likely
- Negative correlation means if one hits, the other is less likely
- Smart bettors look for positively correlated legs that sportsbooks underprice
Break-Even Analysis
What win rate per leg is needed for each parlay size to be +EV? Standard sportsbook odds of -110 imply ~52.38% breakeven per leg on straight bets. For parlays, the required per-leg accuracy goes down slightly because of compounding payouts, but the overall parlay hit rate drops far faster.
Understanding Parlay Mathematics
How Parlays Compound Risk
P(parlay) = P(leg1) × P(leg2) × ... × P(legN)P(all win) = p^N (if each leg has same probability p)Why Sportsbooks Love Parlays
Correlated Parlays
Optimal Parlay Size
Make Smarter Bets
GAMB·8 gives you real-time odds analysis, EV calculators, automated bot strategies, and sports intelligence: everything you need to find edges the sportsbooks don't want you to see.