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Compute combined American odds, decimal odds, payout, and parlay probability for 2-6 leg parlays. Most retail parlays are -EV due to compounded vig and correlation; this calculator shows you the math.
Compute combined American odds, decimal odds, profit on your stake, and the combined implied probability for 2-6 leg parlays. Add a leg by entering its odds; leave a leg blank to skip it.
Combined parlay probability (assuming each leg is independent and priced at its implied probability): --. True parlay probability is usually LOWER than this because each leg's implied probability includes vig. Correlated legs (same-game props especially) break the independence assumption, and the book prices that correlation into same-game parlay odds.
A parlay combines multiple bets into one ticket. All legs must win for the parlay to cash. The payout multiplies across all legs, so combined odds are large. But the probability of all legs hitting is the product of each leg's probability, which is small.
For a 2-leg parlay at -110 each: decimal odds 1.909 × 1.909 = 3.64. American: +264. On a $100 stake, profit is $264. Implied probability of both legs hitting at 52.4% each: 27.4%, which is exactly the break-even rate at +264, so pricing the legs at their own implied probability always shows $0 EV. The fair (no-vig) probability of each -110/-110 leg is 50%, so both hit 25% of the time: EV = 100 × (3.64 × 0.25 - 1) = -$9 per $100, about double the 4.5% house edge on a single -110 bet.
Three reasons retail parlays lose money long-term:
Rare. Two cases:
In both cases, the math has to be checked per-parlay. Default assumption: retail parlays are -EV. See are MLB parlays profitable for the full breakdown.
Sharp bettors place single bets sized by Kelly fraction, not parlays. The math is cleaner, the vig is lower, and the variance is more predictable. Use the Kelly calculator for single-bet sizing.
Convert each leg's American odds to decimal. Multiply all decimal odds together. Convert the product back to American. Example: two -110 legs → 1.909 × 1.909 = 3.64 decimal → +264 American. Stake $100 → profit $264.
Most MLB parlays are not profitable long-term. Compounded vig on a 4-leg -110 parlay is roughly 17% vs 4.5% for a single -110 bet. Correlation on same-game parlays makes the math even worse. The exception is parlays where each leg is independently +EV, which is rare.
From an EV perspective, the best number of parlay legs is one (i.e., bet singles). Each additional leg compounds vig and reduces hit rate. If you must parlay, 2-3 legs minimizes vig damage. 5+ leg parlays are essentially lottery tickets with negative expected value.
Each leg of a parlay carries its own vig. The combined vig is approximately 1 minus the product of (1 - leg vig) for each leg. A 4-leg parlay at -110 each (4.5% per-leg vig) has roughly 17% combined vig. The book's edge on parlays is much bigger than on singles.
Generally no. SGPs bundle correlated legs (e.g., team to win + over the total) at prices that don't credit the correlation to the bettor. The book prices correlation; you pay extra for the convenience. Retail SGP ROI is almost universally negative.