What is a parlay really worth
Why does a bigger payout mean a worse bet?
A parlay pays the product of its legs. Four legs at -110 pay 12.28 to 1. Four fair coin flips should pay 15.00 to 1. The gap is a 17.0% hold — 3.7 times the 4.55% you pay on a single.
Nothing about a parlay creates value. It multiplies the margin, and the payout number grows while the value shrinks, which is exactly why it is the most heavily promoted bet in the market.
| Legs | Hold |
|---|---|
| 2 | 8.9% |
| 3 | 13.0% |
| 4 | 17.0% |
| 5 | 20.8% |
| 6 | 24.4% |
| 8 | 31.1% |
By 7 legs the book is holding more than a quarter of every dollar staked. That is roughly where a parlay stops being a bet and becomes a lottery ticket — which is a fine thing to buy knowingly, and a poor thing to buy while believing you are betting.
The honest exception: if every leg is genuinely +EV, the parlay of them can be too. That is rare and it is not what the promoted parlays are made of.