Bet types & tactics
Parlay
How the payout is calculated
Convert every leg to decimal odds and multiply them together. Three legs at −110 are 1.909 each, so the parlay pays 1.909 × 1.909 × 1.909 = 6.96, which is about +596 in American odds — a $20 ticket returns $139.
The probabilities multiply the same way, which is the half people skip.
If each leg is a genuine coin flip, three legs hit 0.5 × 0.5 × 0.5 = 12.5% of the time. A fair price for a 12.5% shot is +700. The book offers +596, and that gap is the entire story of parlays.
The margin compounds on every leg
A single −110 bet carries about 4.5% hold. Because each additional leg multiplies in another helping of margin, a three-leg parlay holds around 13% and a ten-leg around 37%. Nothing underhanded is happening — it is just what multiplication does to a number slightly below fair.
This is why parlays are the most profitable product on a sportsbook's menu and why they are promoted hardest. The table below is the friendliest possible case: every leg a true 50/50 at standard juice.
Correlation, and why same-game parlays price worse
Ordinary parlays assume the legs are independent. Many aren't: a quarterback throwing for 300 yards and his team going over the total tend to happen together, so a naive multiplication would understate the real probability and hand the bettor an edge.
Books close that gap with same-game parlay pricing, which adjusts for correlation — almost always in their favour. The convenience is real; so is the extra margin buried in it.
The case for and against
Against: on expectation, parlays are the worst price on the board, and the more legs you add the worse it gets. If you are trying to beat the market, adding legs moves you away from that goal, not toward it.
For, honestly: a parlay converts a small stake into a small chance at a large return, and some people want that trade and can afford it. That is entertainment spending, and it is a legitimate thing to want — it just should not be confused with a strategy. If you do bet them, price the ticket first so you know what you are being charged.
| Legs | Hits | Book pays | Fair price | Hold |
|---|---|---|---|---|
| 1 | 50% | −110 | +100 | 4.5% |
| 2 | 25% | +264 | +300 | 8.9% |
| 3 | 12.5% | +596 | +700 | 13.0% |
| 4 | 6.25% | +1228 | +1500 | 17.0% |
| 5 | 3.13% | +2436 | +3100 | 20.8% |
| 6 | 1.56% | +4741 | +6300 | 24.4% |
| 10 | 0.10% | +64,208 | +102,300 | 37.2% |
Best case, not worst: real legs are rarely true coin flips and same-game parlays are priced for correlation on top of this.
The common mistake: adding a leg to "boost the payout"
Adding a leg does raise the payout — and lowers the probability by more, which is why the hold climbs with every leg. Going from three legs to four takes the ticket from about 13% hold to 17%, and from a 12.5% chance to 6.25%. The number on the bet slip gets bigger while the bet gets worse. If a big payout is the goal, a single longshot at a fair price is a cheaper way to buy the same variance.
Related terms
Common questions
- What is a parlay bet?
- A parlay is one ticket combining several bets where every leg must win for it to pay. The legs' odds multiply, so the payout grows quickly — but so does the chance of losing, and the sportsbook's margin compounds on every leg.
- How are parlay odds calculated?
- Convert each leg to decimal odds and multiply them. Three legs at −110 are 1.909 each: 1.909 × 1.909 × 1.909 = 6.96, or about +596. Our free parlay calculator does this for any mix of prices and stake.
- Why are parlays considered bad bets?
- Because the sportsbook's margin compounds with each leg. A single −110 bet holds about 4.5%; three legs hold about 13% and ten legs about 37%. You are paying several times the usual commission for the same underlying opinions.
- What are the odds of hitting a 10-leg parlay?
- If every leg were a true coin flip, about 0.10% — roughly one in a thousand. The book typically pays around +64,208 on that, where a fair price would be +102,300.
See these numbers on your own bets
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