Price a parlay before you build it.
Enter each leg’s American price and a stake. The calculator multiplies the legs into one combined price and shows the payout — and the probability you are actually buying.
How parlay pricing works
A parlay is multiplication. Each leg converts to decimal odds and the decimals multiply into one number. Two -110 legs are 1.91 × 1.91 = 3.64 — a +264 ticket. Every leg must cash; one loss zeroes the ticket. The upside is real leverage, and the calculator shows exactly how much you are paying for it.
The implied probability falls fast. A single -110 leg carries a 52.4% implied probability. Two legs drop the combined chance to 27.4%; five legs of the same price sit under 4%. The combined probability is on the board next to the payout because the second number means nothing without the first.
The juice compounds with the legs. Each leg carries the book’s margin, and multiplying legs multiplies the margin. That is why a two-leg -110/-110 parlay pays +264 when two fair coin flips are worth +300. Measure any single market’s cut with the vig calculator and multiply from there.
Correlation breaks the math. The combined price assumes independent legs. When outcomes move together — a quarterback and his receiver, a total and a spread in the same game — straight multiplication overstates fair value, which is exactly why books reprice same-game parlays.
How the calculator works
01
Each leg’s American price converts to decimal odds.
02
The decimals multiply into one combined price — and so does the vig in each leg.
03
Read the payout and the implied probability before the book reads them for you.
Parlay questions
- How are parlay odds calculated?
- Convert each leg to decimal odds and multiply them together. Two -110 legs are 1.91 × 1.91 = 3.64, or +264 in American terms. The payout is stake × combined decimal; the profit is that minus your stake.
- Why is the parlay payout lower than the legs suggest?
- Every leg carries the book’s vig, and multiplying legs compounds it. Two -110 legs pay +264 against a fair +300 for two independent coin flips — the 36-point gap is stacked juice. Check any single market’s margin with the vig calculator.
- How many legs can I calculate?
- Up to 12. Past a handful, each added leg multiplies a small win probability into a very small one — the calculator shows the combined implied probability so the decay is visible before you build the ticket.
- Does the calculator handle same-game parlays?
- It prices independent legs only. Correlated legs — a quarterback and his top receiver — do not multiply cleanly, which is why books reprice same-game parlays instead of using this math. Treat the output as an upper bound on fair value there.
Building this slip for real? Track the ticket and we will grade every leg against the close.