16. September 2026
What Is a Parlay Bet? How Odds Multiply and What It Costs
What a parlay bet is, how the odds multiply leg by leg, why the margin grows with every pick, and when a Bet Builder or system bet makes more sense.
A parlay is several bets stitched into one ticket. Every leg has to win, and if they all do, the odds multiply together into a payout no single bet would give you. Lose one leg and the whole thing is gone, no matter how well the others did.
British punters call it an accumulator. On the Jacks Club betslip it's the Combo tab. Same bet, three names.
What is a parlay bet?
Here's one we could have built from our own board on 16 September. Three NFL favourites on the moneyline: Buffalo at 1.42 against Detroit, New England at 1.41 against Pittsburgh, Chicago at 1.40 against Minnesota.
As three separate bets, each of those pays about 40 cents per dollar staked. Put them on one ticket and the price becomes 2.80. So a $20 parlay would return $56 if Buffalo, New England and Chicago all win. If any one of them slips up, the $20 is lost.
That's the deal a parlay offers. Bigger payout, but every pick has to land.
How parlay odds are calculated
Multiply the decimal odds. That really is the whole method. 1.42 times 1.41 times 1.40 gives 2.80, give or take a rounding.
American odds need converting first. A -110 price is 1.909 in decimal, and stacking legs at -110 goes like this:
Two legs come out at 3.64, which is about +264.
Three legs reach 6.96, or roughly +596.
Four legs climb to 13.28, near enough +1228.
Now compare those with what the bets would pay if every leg were a true coin flip with no margin on it: +300 for two legs, +700 for three, +1500 for four. The gap between the two sets of numbers is the part people tend to skip.
What a parlay really costs
Every leg carries the book's margin, and a parlay doesn't add those margins together. It multiplies them.
A single bet at -110 on a genuine 50-50 hands back about 95.5 cents per dollar over the long run, so it costs 4.5%. Put two of those legs together and the cost is 8.9%. Three legs, 13%. Four, around 17%. The longer the ticket, the bigger the slice.
Our three favourites tell the same story with real prices. Each of those moneylines carried about 6% of margin (our guide to the vig shows how to measure it). Bet singly, you'd give up roughly 5.8% on each. Combined into the 2.80 parlay, that becomes something like 16%.
Which is fine if you know it going in. A parlay is a small stake chasing a big number, and you pay extra for the size of that number.
How many legs is too many?
There's no rule, but the maths turns ugly quickly. Five coin-flip legs at -110 pay about +2436, and a ticket like that lands roughly once in every 32 tries. Over time it hands back about 79 cents per dollar, so a fifth of everything you stake goes to the margin.
That's why plenty of regular parlay players stop at two or three legs. The ones who don't tend to be the ones sharing screenshots of a single leg that let them down.
Why three favourites aren't a safe parlay
Short prices feel safe. Put three of them together and it's easy to think you've built a near-certainty that pays almost triple.
Take the margin out of those three moneylines and each favourite comes out at about two chances in three. Multiply those chances and all three win together only about 30% of the time. The 2.80 ticket needs 35.7% just to break even, so on those numbers you'd lose it seven times in ten.
Favourites lose every weekend in the NFL. Stack three and you're asking for none of them to be the one that does.
Same-game parlays and the Bet Builder
Try to put two picks from the same game into a normal Combo and our betslip stops you with "Selections cannot be combined". That's deliberate, because outcomes inside one game are linked. A favourite running up a big win and the game going over its points total often happen together, so simply multiplying those two prices would get the payout wrong.
For that, NFL games have a Bet Builder tab. On the Buffalo v Detroit game it listed 76 markets, and it prices the legs you pick as one bet. Don't expect that price to match the legs multiplied together, for exactly that reason.
System bets: a parlay with a safety net
The betslip's System tab splits your picks into every smaller parlay they can make. American books often call this a round robin.
With our three favourites, a "2 from 3" system is three separate two-leg parlays: Buffalo and New England at about 2.00, Buffalo and Chicago at 1.99, New England and Chicago at 1.97. At $5 each that's $15 staked.
If all three win, all three doubles pay and you get back $29.82.
If one favourite loses, say Chicago, only the Buffalo and New England double survives, and it returns $10.01. You're down about $5 rather than wiped out.
The trade is plain enough. You stake more to cover the same picks, and the top payout is smaller, but one bad leg no longer kills the ticket.
When does a parlay make sense?
When you want a small stake to have a shot at a large return and you accept that it usually loses. That's the honest use.
The other case is when you think every leg is priced wrong in your favour. Then the multiplication works for you instead of against you. If your picks are closer to guesses, though, the parlay just makes the guessing more expensive, so keep the stakes small and the legs few.
Want a view on the margin rather than the winner? Those legs can be spreads too. Our spread betting guide explains lines like -5.5 and why the half point matters.
How to build a parlay at Jacks Club
Pick from different games. Head to the sportsbook, open a sport such as American football and tap the prices you want.
Open the Combo tab in the betslip. It shows the total odds and your potential win before anything is placed.
Check each leg's market name. "Winner (incl. overtime)" and a handicap line settle differently, and one wrong click changes the bet.
Keep the stake sensible. Every extra leg lowers the chance of a payout, so the stake should shrink as the ticket grows.
Stakes are shown in dollars and come out of whichever coin you've deposited. Betting on the NFL all season? The NFL betting guide covers the markets worth knowing, and there's more on fight-night combinations in our UFC betting guide.