How Parlay Odds Are Calculated
When you combine bets into a parlay, the odds multiply. Each leg's payout rolls into the next. The combined odds are the product of all individual decimal odds:
3-team parlay at -110 each:
Each at -110 = decimal 1.909
Parlay decimal: 1.909 × 1.909 × 1.909 = 6.96
$100 stake → $696 total payout → $596 profit
Win probability: 1/6.96 = 14.4%
Standard Parlay Payouts at -110
| Legs | True Win Prob | Fair Parlay Odds | $100 Profit |
|---|---|---|---|
| 2-leg | 22.7% | +341 | $341 |
| 3-leg | 12.5% | +696 | $696 |
| 4-leg | 6.9% | +1,329 | $1,329 |
| 5-leg | 3.8% | +2,538 | $2,538 |
| 6-leg | 2.1% | +4,847 | $4,847 |
The Real Cost of Parlays
Every leg of a parlay carries the sportsbook's juice. That vig compounds with each additional leg. A 3-leg parlay built from standard -110 bets already has ~13% edge removed for the house before a single game is played. Extend to 5+ legs and the EV becomes deeply negative — even if every individual pick is a coin flip.
This is why sportsbooks offer "parlay insurance," "no-sweat parlay" promotions, and SGP boosts — they know parlays are their most profitable products. The high payout is the hook; the compounded vig is the trap.
When Parlays Have Value
A parlay is +EV if — and only if — every individual leg is already +EV on its own. If Leg A has +3% edge and Leg B has +4% edge, combining them into a parlay preserves and compounds those edges. The problem is most recreational bettors don't have +EV individual picks to begin with.
"Correlated parlays" can add additional value when outcomes are logically linked in ways the book hasn't fully priced — for example, betting a team to win AND their quarterback to throw for 300+ yards when the team already needs to pass heavily to win. These correlations are sometimes underpriced in same-game parlays.
Build Parlays From Genuine +EV Legs
Sibyl shows the model edge on every single pick. When you know which legs have real value, you can combine them with confidence — instead of guessing.
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