According to the University of Nevada’s Center for Gaming Research, the state’s sportsbooks earned, on average, 5.7 cents on every dollar wagered on football in 2021. They earned 5.5 cents on every dollar wagered on basketball and 4.8 cents on every dollar wagered on baseball.
Parlays, however, resulted in a windfall of 32.1 cents per dollar, illustrating why so much of the advertising, promotional odds boosts and other marketing incentives from sportsbooks now revolve around parlays. DraftKings CEO Jason Robins told attendees at the Goldman Sachs Travel and Leisure Conference in June that his organization’s focus on parlays would further intensify.
“What we are doing is trying to get smart at eliminating the sharp action or limiting [it] at least … and then also making sure that we have a high parlay mix because people do like that,” Robins said.
Sportsbooks do so well on parlays because each of the individual bets need to win to cash the parlay. Lose one, and the whole wager is graded as a loss. How likely the parlay is to cash depends on the likelihood of each wager included. If you have two wagers that are each +100 — bet $100 to win $100 — then the parlay has roughly a 25 percent chance of winning. If those wagers are each -110 (bet $110 to win $100) the chances improve to 27 percent, but the payoff will also be slightly lower to reflect those odds.
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Where many bettors get in trouble is chasing big scores with multiple-legged parlays that often feel like a sure thing. A six-leg parlay in which each leg has odds of -233 — implying a 70 percent chance of winning each leg — may feel like a relatively safe bet. In reality, it only has about a 12 percent chance of winning.
And in single-game parlays — an increasingly popular option in which bettors must select multiple bets from within the same game — you could get penalized for choosing wagers that are correlated, meaning there is a positive relationship between the bets that makes them more likely to be successful.
Here’s an example from this baseball season. Let’s pretend we wanted to create a single-game parlay on FanDuel for a June game between the New York Mets and Milwaukee Brewers. We want to take over eight total runs, offered at -110 odds. We also want to add a Pete Alonso home run at +310 odds, giving us a single-game parlay with two wagers that will pay +485.
But those two events are correlated. More home runs typically mean more runs scored. If we instead switch the run total bet to under eight runs, also at -110, but keep the Alonso home run prop — giving us two uncorrelated events in the same game — the potential return is bumped up to +980 despite the odds for each wager being exactly the same (+310 and -110). The fair value for this parlay, taking into consideration the prices of the two bets, is around +680. In other words, the correlated parlay is vastly underpaying bettors, while the uncorrelated parlay is overpaying. Not all sportsbooks penalize you in this way, so make sure you compare prices at different outlets.
Single-game parlays could also have different rules, even for the same bet. On DraftKings, for example, if you place a straight wager on a player getting a hit in an MLB game, he has to start and record at least one plate appearance for the bet to be live. If that same wager is part of a single-game parlay, the player only needs a plate appearance. In other words, he could pinch hit later in the game for one at-bat and the bet would be considered live, an obvious disadvantage to the bettor.
There are also situations in which the prices themselves are different for the same bet, depending on if it is used in a single-game parlay or not. Here is the exact same game offered on DraftKings both as straight wagers (top) and as part of a single-game parlay (bottom). There are different prices for the money line, run line and over/under totals, despite them being the same wagers. (Not all the differences are in a disadvantageous direction for bettors.)
Then there are the odds “boosts” sportsbooks offer, many of which come via two- or three-leg parlays. Caesars this season offered to “boost” a two-leg parlay — which required Bryce Harper and Jorge Soler to each hit a home run in a game — to +1200, a juicy-sounding number. That same wager, however, could be had at +1846 odds at FanDuel using a single-game parlay without a boost. Sportsbooks, in other words, are selling a product — so don’t assume their enthusiasm around special parlay offers necessarily means they have any value for bettors.
Finally, be wary of any promoted parlays. These typically involve a few favorites strung together to give the illusion of a short cut to a winning bet; clearly, that is far from the case. DraftKings promoted a parlay during the baseball season that included the Houston Astros winning (-180), the Atlanta Braves winning (-280) and no run being scored in the first inning of a Colorado Rockies-Arizona Diamondbacks game (-125). The promoted parlay offered +280 odds, but the fair-value price — based on the Pinnacle sportsbook, once you removed the vig — was +320. On paper, three bets at minus odds — which each should be favored to win — looks like a promising 3-0 ticket, but the math (and reality) is very different. Even if you had three overwhelming favorites at -250 odds each — implying a 71 percent win rate per leg — you would still only have a 36 percent chance of going 3-0.
Are parlays a big winner for the house? Absolutely. Does this mean you should avoid them altogether? No. Just like any bet, if you believe you have an edge, you should bet accordingly. If you believe you have an edge in multiple games, then it makes sense to parlay those together for an increased payoff.
But by impulsively betting parlays at every turn, you will be enriching the house more often than your own bankroll.
Illustration by Lily LK for The Washington Post.