Parlay odds are calculated by multiplying each leg's decimal odds together. That single rule explains everything — and once you see it with real numbers, it clicks fast.
What Is the Conversion Formula?
American odds first need to be converted to decimal. For negative odds, the formula is: 100 ÷ |American odds| + 1. So -110 becomes 100 ÷ 110 + 1 = 1.909.
For positive odds: (American odds ÷ 100) + 1. So +150 becomes 1.50 + 1 = 2.50.
Once every leg is in decimal form, multiply them all together. The result is your combined decimal payout. Subtract 1 to express it as American-style profit on a $100 stake.
Not sure what a "leg" means in this context? Our Parlay Betting Glossary — Legs, Pushes, Teasers & More covers the full vocabulary.
How Does a Two-Leg -110/-110 Parlay Work Out?
This is the most common example. Both sides of a standard spread are priced at -110.
- Convert: 100 ÷ 110 + 1 = 1.909 (each leg)
- Multiply: 1.909 × 1.909 = 3.644
- Subtract 1: 3.644 − 1 = 2.644
- In American odds: roughly +264
A $100 bet returns about $264 in profit, $364 total. That is the math behind a standard two-teamer.
What Happens When You Add More Legs?
Each added leg multiplies the payout — but also multiplies the book's edge against you. Industry veteran Micah Roberts, a former sportsbook director with 20-plus years of experience, put it plainly: "Once you start playing parlays with three teams or more, you don't get true odds. You're losing value each time you add a team."
The table below shows how a straight string of -110 legs compounds.
| Number of Legs (all -110) | Decimal Parlay Odds | Approximate American Odds | $100 Profit |
|---|---|---|---|
| 2 | 3.64 | +264 | $264 |
| 3 | 6.96 | +596 | $596 |
| 4 | 13.29 | +1,229 | $1,229 |
The payouts look appealing. But every leg you miss zeroes the ticket. That risk-reward tradeoff is worth understanding before you build a ticket — see our Parlay vs Straight Bet — Which Is the Better Play? breakdown for a fuller picture.
What About Same-Game Parlay Odds?
Same-game parlays work differently. Because the legs come from one game, outcomes can be correlated. Sportsbooks typically add an extra 10% to 20% of house edge above standard parlay hold to account for that correlation risk. Posted odds are often meaningfully below what the true math would produce.
We dig deeper into that markup in our guide to What Is a Same-Game Parlay and Is the Extra House Edge Worth It?.
What Happens If One Leg Pushes?
A push (a tie result) voids that leg. The parlay reverts to the next lower number of legs and pays at the adjusted odds. It does not kill the ticket — it just shrinks the payout.
New to parlays altogether? Start with What Is a Parlay Bet? A Plain-English Explanation before going deeper on the math.
If you want to put this formula to work with today's slate, our free daily parlay suggestions apply these same principles to current lines across the NFL, NBA, MLB, and more. Parlay betting is legal in the approximately 30 states that offer regulated mobile sports betting as of 2026; confirm your state's status on our Parlay Betting Legality by State page. Must be 21+ (18+ in some states). Gambling problem? Call 1-800-GAMBLER.