Parlays and same game parlays: payouts, margin and correlation

A parlay links two or more bets into one ticket. Every leg has to win, and in return the payout grows with each leg you add. Same game parlays apply the same idea to several outcomes in one game. Both are popular on Canadian books, and both are more expensive than they look.

This guide explains how parlay payouts are calculated, why the bookmaker's margin gets bigger with every leg, how correlated legs change same game parlay prices, and walks through an NHL and NBA parlay from start to settlement. For the NBA markets themselves, including how overtime affects spreads and totals, see our guide on how to bet on the NBA.

How does a parlay work?

You pick several selections, called legs, and stake one amount on all of them together. If every leg wins, you are paid at the combined odds. If any leg loses, the whole parlay loses. In Canada you will also see parlays called multis, accumulators or combos.

Parlays have a long history here. Before 2021, provincial lotteries could legally offer sports bets only as parlays of at least two events, which is why products like Pro-Line and Mise-o-jeu were built around them. Single-game betting became legal when Bill C-218 came into force in August 2021, but the parlay has stayed a fixture of the Canadian betting menu.

How are parlay payouts calculated?

Convert every leg to decimal odds and multiply them together. The result is the parlay's decimal price.

• Parlay odds = leg 1 x leg 2 x leg 3 ...
• Total return = stake x parlay odds

Two legs at 1.91 (-110 each) give 1.91 x 1.91 = 3.65, or roughly +265. Three legs at 1.91 give 6.97, roughly +597. If you are working from American odds, convert them first; our odds explained guide has the formulas. Our parlay calculator takes American or decimal odds for each leg and gives the combined price and payout.

The growth is what makes parlays appealing. The next section is what makes them costly.

Why do parlays have a higher house edge?

Each leg carries the book's margin, and when you multiply the legs you multiply the margins too. A casino game such as dice works differently, with the same flat edge on every bet, as our bitcoin dice guide shows.

Take a fair coin-flip market priced at -110 on both sides. A fair price would be 2.00; the book pays 1.91. On a single bet, your expected return is 0.5 x 1.909 = 0.9545, so you lose about 4.5 cents per dollar on average. On a parlay of these legs, your expected return is 0.9545 raised to the number of legs:

A four-leg parlay of -110 bets costs you, on average, about 17 cents of every dollar staked. That is close to four times the cost of a single bet. The more legs, the more of the payout goes to the book in expectation.

Two practical consequences follow. First, a big parlay win does not mean the parlay was a good bet; long odds pay well precisely because they rarely land. Second, if you like several bets independently, placing them as singles keeps the cost per bet at the single-market margin. To check the margin on each leg before you combine them, enter both sides of the line in our no-vig calculator.

What happens if a parlay leg pushes or is void?

At most books, a leg that pushes (lands exactly on a whole-number line) or is voided (a postponed game, a scratched player on a prop) is removed, and the parlay is recalculated on the remaining legs. A three-leg parlay with one push becomes a two-leg parlay at the lower combined price. If every leg but one is removed, the bet settles as a single. Some books treat specific promotions or same game parlays differently, so check the rules section on multiples.

What is a same game parlay?

A same game parlay (SGP), sometimes called a same game multi, combines several bets from a single game: for example, a team to win, the total over, and a player to record a point. Standard parlays usually block legs from the same game, because the outcomes are linked. Same game parlays allow them and price the combination with their own model.

What are correlated legs?

Legs are correlated when one outcome makes another more or less likely. In a hockey game, a favourite winning by two or more goals and the game going over 6.5 are positively correlated: lopsided scores tend to have more goals. A team winning and its top scorer scoring are positively correlated too.

If a book simply multiplied correlated legs, it would overpay, because the combination happens more often than the product of the separate probabilities suggests. So books adjust the price down.

Here is a hypothetical example. A team to win is 1.80 and its leading forward to score anytime is 2.50.

• Multiplying the legs gives 1.80 x 2.50 = 4.50, an implied 22.2%.
• A same game parlay builder might offer 3.90 instead, an implied 25.6%.

The book is saying the two outcomes together are more likely than independent pricing implies. That adjustment is reasonable in principle. The problem for bettors is that you cannot see how much of the gap is the correlation and how much is extra margin. Operators' own published results point to same game parlays being among their most profitable products, and the more legs you add, the harder the true cost is to estimate.

Negatively correlated legs work the other way: a heavy underdog to win plus the under on a low total might be priced higher than the simple product, or blocked entirely.

Worked example: an NHL and NBA parlay

Here is a three-leg parlay across two sports on the same night. The prices are illustrative.

Combined odds: 1.80 x 1.91 x 2.05 = 7.048, or about +605.

On a $20 stake: total return $140.96, profit $120.96.

Implied chance of all three landing, at the book's prices: 1 / 7.048 = 14.2%. Because each leg includes margin, the true chance is lower than that if the book's prices are accurate.

Now three ways the night can go:

1. All three win. You are paid $140.96.
2. The NBA favourite wins by exactly 4. The -4.5 leg loses, so the parlay loses, even though both hockey legs won.
3. The NBA line had been -4 instead, and the favourite wins by 4. That leg pushes. The parlay is recalculated on the two NHL legs: 1.80 x 2.05 = 3.69, so the $20 stake returns $73.80.

Because the hockey game in leg 3 is a different game from leg 1, these legs are treated as independent and a standard parlay accepts them. Had you tried to pair the leg 1 moneyline with that same game's puck line, most books would refuse it in a standard parlay and send you to the same game builder. For how NHL totals settle when a game goes to a shootout, see our guide to betting on the NHL. If you are new to the single-game market behind most legs, our guide to moneyline betting covers how those prices work.

What is a round robin bet?

A round robin splits your picks into every possible smaller parlay, so one losing leg does not sink everything. Using the three legs from the example above "by 2s" creates three two-leg parlays:

That costs $15 in total. If the NBA leg loses and both hockey legs win, only the second parlay pays: $18.45 back on $15 staked. If all three win, you collect $55.22. A round robin softens the all-or-nothing nature of a parlay, but every combination is still a parlay with compounded margin, and you are placing more of them.

Are parlay boosts and insurance worth it?

Many books, including several of the books we review, offer parlay profit boosts or "one leg loses" refunds, usually paid as a bonus bet rather than cash. A boost raises the payout on a winning ticket, which can offset some of the compounded margin, but read the terms: boosts often have a maximum stake, a minimum number of legs, minimum odds per leg and a cap on the extra winnings. A refund in bonus bets is worth less than the same amount in cash, because bonus bets usually return only the profit, not the stake. Many books also let you cash out a parlay before the last leg settles; our guide to cash out betting shows how to work out what the ticket is worth.

Whichever book you choose from our best betting sites in Canada, read its rules on multiples before you rely on a parlay promotion.

Responsible gambling

Parlays are designed to be exciting: small stakes, large possible returns, and near misses that make the next ticket feel close. Keep stakes small, track what you spend over a month rather than ticket by ticket, and use your account's deposit limits.

If it is getting harder to stop, talk to someone. ConnexOntario (Ontario) is at 1 866 531-2600, and Jeu: aide et référence (Quebec) is at 1 800 461-0140, both free and confidential. Our responsible gambling page lists services in every other province, plus how to set up a cooling-off period or self-exclusion.