Parlay Betting Explained
A parlay combines two or more wagers into a single ticket. All legs must win for the parlay to cash — but the payout is much higher than betting each leg individually. Parlays are sportsbooks' most profitable product line, which tells you something about their expected value to bettors.
How Parlay Payouts Are Calculated
Each leg's decimal odds are multiplied together. Example: three –110 favorites in a parlay:
- Each leg: 1.91 decimal (American –110)
- Combined: 1.91 × 1.91 × 1.91 = 6.97x — a $10 parlay returns $69.70
The Compounding Vig
Each leg includes the sportsbook's vig (~4.5% on –110 / –110 markets). When you parlay, that vig compounds:
- 1-leg fair price: ~50%
- 3-leg true odds vs. payout: ~12.5% true vs. ~14.3% payout — the book holds ~6.6%
- 5-leg: book holds ~10–12%
- 10-leg: book holds ~20%+
This is why bookmakers heavily promote parlays. The expected loss per dollar wagered grows with each added leg.
Same-Game Parlays (SGPs)
An SGP combines bets from the same game (e.g., Trail Blazers –4 + over 226.5 + Anfernee Simons 25+ points). SGPs are correlated — if the Blazers cover, the total is more likely to go over, and the star's points are more likely to be high. Sportsbooks adjust SGP pricing to account for correlation, but they don't fully adjust — which is why some bettors search for "uncorrelated" SGP legs that the book over-prices for correlation.
Oregon Example: 3-Leg Parlay
- Trail Blazers ML +160
- Timbers over 2.5 goals –115
- Seahawks –3.5 –110
Decimal odds: 2.60 × 1.87 × 1.91 = 9.28x. A $20 parlay returns $185.60.
When Parlays Make Sense
- Long-shot futures bundling: Two long underdogs you genuinely think are underpriced
- Correlated SGPs that the book underprices for correlation
- Promo / boost parlays: When DraftKings offers a 30% profit boost on a 4+ leg parlay, the math can flip in your favor
When They Don't
- "For fun" big-money lottery parlays — these are entertainment, not investment
- 5+ leg straight parlays — the vig compounds beyond reasonable thresholds
- Correlated legs the book correctly prices — no edge available