How much do parlays really cost?
Far more than single bets. Every leg you add multiplies the bookmaker’s margin: with legs at −110 a parlay costs about 9% with two legs, 13% with three and 21% with five, against 4.5% for a single bet.
With every leg at −110, a parlay’s house edge is 8.88% with two legs, 13.03% with three, 20.75% with five and 37.20% with ten. In 2025, New Jersey’s sportsbooks kept 19.2% of the money bet on parlays and 4.9% of the money bet on everything else.
Simulate 500 three-leg parlaysThe house edge of every sports bet
What a parlay costs, by number of legs
| Legs | Chance to win | Pays | A fair bet would pay | House edge |
|---|---|---|---|---|
| 2 | 25% | 2.64 to 1 | 3 to 1 | 8.88% |
| 3 | 12.5% | 5.96 to 1 | 7 to 1 | 13.03% |
| 4 | 6.25% | 12.28 to 1 | 15 to 1 | 16.98% |
| 5 | 3.125% | 24.36 to 1 | 31 to 1 | 20.75% |
| 6 | 1.563% | 47.41 to 1 | 63 to 1 | 24.36% |
| 8 | 0.391% | 175.45 to 1 | 255 to 1 | 31.08% |
| 10 | 0.098% | 642.08 to 1 | 1,023 to 1 | 37.20% |
Why
A parlay pays the product of its legs’ prices, and each of those prices is a little short of fair. Multiply prices that are each 4.5% short and the shortfall compounds, the way interest does. The payout looks big because the chance of winning is small: three legs that could each go either way win one time in eight and pay just under 6 to 1, where a fair bet would pay 7 to 1. In New Jersey, parlays were about a third of the money bet in 2025 and about two thirds of what the books won.
500 bets of 10: single bets against three-leg parlays
| Result | Single bets | Three-leg parlays |
|---|---|---|
| Finished ahead | 15.2% | 11.3% |
| Down to half at some point | 14.6% | 76.7% |
| Went broke | 0.0% | 35.0% |
| Average result | −229 | −593 |
| Expected per 100 staked | −4.55 | −13.03 |
Each column is 10,000 simulations of 500 bets of 10, starting with 1,000, by a bettor whose every pick could go either way. The link above replays the parlays.