Compare n' Bet™
Compare n' Bet™
Parlays are fun, big-payout bets that the sportsbook industry loves because they make them more money than almost anything else. This guide covers the math, when parlays make mathematical sense, and why most of the ones people bet are bad bets.
A parlay is a combination bet. You pick multiple outcomes (called "legs") and combine them into one wager. Every leg must win for the bet to pay out. If any single leg loses, the whole parlay loses.
The appeal is the payout. Because you're stacking probabilities, the potential return is much larger than the sum of betting each leg individually. A two-team parlay of two standard -110 favorites pays about +264 instead of the +90 total you'd get betting them separately with the same stake.
Hit a 5-leg parlay and you're looking at around a 25-to-1 payout. Hit a 10-leg parlay and it can be 600-to-1 or more. Those numbers are why parlays are the most-bet format at every American sportsbook.
A fair parlay payout (no vig) is calculated by multiplying the decimal odds of each leg together.
Two -110 bets in decimal form are 1.91 each. Multiplied: 1.91 x 1.91 = 3.65, which is +265 in American odds. The actual parlay payout at most books is about +264, which is essentially fair. With no vig, a two-team parlay would pay +280.
The vig adds up leg by leg. Each leg of a parlay carries its own hold, and the house takes a cut at each step. By the time you're on a 5-leg parlay, the effective hold is often 15-20%, compared to the 4.5% hold on a single bet. That's three to four times the house edge.
To break even on a 2-leg parlay with -110 bets, you need each leg to win 52.4% of the time (same as a single bet). To break even on a 5-leg parlay, each leg still needs to win about 52.4% of the time. The break-even per-leg percentage stays the same, but the overall parlay hit rate drops to about 4%.
This sounds fine. The catch is that if your actual hit rate per leg is only 50% (break-even on a no-vig basis), your 5-leg parlay will hit only 3.1% of the time. At a 600-to-1 payout, that's a significant losing proposition.
Parlays are the biggest single driver of sportsbook hold percentage. Industry-wide data suggests books make 20-30% hold on parlay action compared to 4-5% on straight bets.
Why? A few reasons. First, vig compounds across legs, as explained above. Second, casual bettors pick parlay legs based on what they want to win rather than where the value is, which means the individual legs often have negative expected value on their own. Third, the allure of a big payout makes people bet larger stakes on parlays than they normally would, which doesn't help their long-term bankroll when the parlay loses.
Every sportsbook app has a "Parlay of the Day" or highlighted parlay offers. Every marketing push emphasizes parlays. This is not a coincidence. The books want you playing parlays. Understand that when you're tempted.
Despite the math, there are a few specific cases where parlays can be reasonable.
If you genuinely believe each of your legs has positive expected value on its own, combining them into a parlay compounds that edge. A 2-leg parlay of two bets you already liked (each at 55% true win probability) is mathematically better than the two single bets because the edges multiply.
The key word is "genuinely." If you're picking legs because they feel right or because you're hyped about the game, you're not actually finding edges. You're just stringing together bets you like and paying the book extra vig for the privilege.
If you're making a $5 parlay on Sunday games so you have something to cheer for all day, that's a valid use of entertainment dollars. It's a bad bet mathematically but it's a fun bet. Just recognize it as entertainment, not strategy.
Many sportsbooks offer free bet credits that can only be used on parlays (with specific minimum leg counts). In those cases, the free bet changes the math significantly because you don't lose your stake if the parlay fails. Using free bets on big parlays is often the right play because the downside is just losing the "free" credit.
Most casual parlays combine bets that don't have independent outcomes. Betting the favorite to win AND the over in the same game is a classic example. If the favorite is blowing out the opponent, scoring is high and the over hits. But if the favorite is struggling, the over might miss. The outcomes are correlated, and standard parlay prices don't account for this.
Until recently, sportsbooks typically rejected these correlated parlays. Now, books have sophisticated tools that let them recalculate parlay prices for correlated legs. The problem for bettors is those recalculated prices are almost always shaded heavily in the book's favor.
As noted, each leg adds its own vig to the overall hold. A 5-leg parlay isn't priced with one 4.5% vig. It's priced with 4.5% vig applied five times, compounding. That's structural loss.
Casual bettors often focus on the parlays that "just barely" missed. "I was one leg away from a $1,000 payout." That framing is wrong. A 5-leg parlay is supposed to miss most of the time. Being "one leg away" is the most common outcome of a losing 5-leg parlay, not a unique stroke of bad luck.
Same-game parlays are parlays where all the legs come from a single game. You might combine the Lakers moneyline with Luka Doncic over 27.5 points and the over on the game total. Every leg must hit for the parlay to pay.
Because the legs are correlated (a Lakers win often correlates with Doncic scoring more points and the game going over), the books recalculate the parlay price using their own correlation models. The resulting prices include significant extra vig beyond standard parlay pricing.
Industry data consistently shows SGP hold is the highest of any common bet type at most sportsbooks, often 15-25%. The payouts look big, but the true expected value is worse than almost any other bet structure.
If you have a very strong narrative for a specific game (you think a team blows out their opponent and their star scores heavily), an SGP lets you express that belief concisely. But the vig penalty is severe, and even if your read is correct, you're paying a lot for the privilege of expressing it this way.
A better approach is often to bet one or two individual pieces of the thesis at straight prices (the moneyline and the over, separately) rather than combining everything into a single SGP.
Sportsbooks offer "boosted" parlays with enhanced odds. A 4-leg parlay that would normally pay +1100 might be boosted to +1500.
Boosts are one of the few places where parlays can genuinely be good value. If the boost is large enough to more than offset the hold, the expected value flips positive.
Say a parlay has a true (fair) price of +1300 and the book normally offers +1100 (keeping some vig). A boost to +1500 gives you better than fair odds, which means positive expected value for the bettor.
The catch: book's boosts are usually on parlays of popular bets that are shaded on individual legs. The "fair" price of the parlay might not actually be +1300 if each leg is priced off the sharp market. Still, big boosts on popular Sunday parlays are often reasonable plays, particularly when limited in frequency.
A teaser is a parlay where you're allowed to adjust the point spread or total on each leg in your favor by a set amount (usually 6 points in football, 4 in basketball). The payout is reduced accordingly.
The most famous teaser structure. You move each leg by 6 points toward the side you're taking. A -7 favorite becomes -1. A +3 underdog becomes +9. The payout on a 2-team teaser is typically around -120 or so.
The Wong teaser (named after Stanford Wong) involves teasing NFL lines through both key numbers, 3 and 7. Moving +1 to +7 crosses both numbers, dramatically increasing the hit rate. Historical data shows these teasers have been profitable bets for decades when used selectively.
The catch: modern sportsbooks have wised up. Prices on teaser structures through key numbers have been adjusted to reduce the historical edge. The math isn't as good as it used to be, but selective Wong teasers can still be reasonable value.
4-point teasers on NBA spreads move each leg by 4 points. Because basketball doesn't have strong key numbers, the per-leg hit rate improvement is much smaller than in the NFL. NBA teasers are generally not good value and should be avoided.
Parlays are fun. They can be a valid part of a bettor's toolkit, particularly in promotional situations or when you have real edges on individual legs that multiply into strong compound value. They are not the shortcut to profit that the big payout numbers suggest.
Most of the parlays casual bettors place are negative expected value, and the more legs you add, the worse the math gets. If you want to win long-term, your main bets should be straight singles where you've found real edges. Parlays can live in your betting menu as entertainment or for specific promotional plays, but don't let the sportsbook's marketing convince you they're a strategy.
This guide is for informational purposes only. Compare n' Bet does not offer gambling advice or predictions. Please gamble responsibly.