KEY TAKEAWAYS

• A favorite is the side a sportsbook expects to win a matchup; an underdog is the side expected to lose.
• Sportsbooks signal this through the sign of the odds: a minus sign marks the favorite, a plus sign marks the underdog.
• The label reflects relative likelihood, not certainty — underdogs win regularly.
• Because favorites are judged more likely to win, a winning favorite bet pays less profit per dollar risked than a winning underdog bet.
• The same team can be a favorite in one game and an underdog in the next — the label applies to the matchup, not the team permanently.
• This article covers what the labels mean and why they matter; the full math of converting odds to probability lives in a separate guide.

In sports betting, a favorite is the team or player a sportsbook expects to win a given matchup, and an underdog is the side expected to lose. These aren’t official designations handed down by a league — they’re a sportsbook’s shorthand for relative likelihood, and it expresses that likelihood through the sign of the odds it posts: a minus sign for the favorite, a plus sign for the underdog. Understanding this distinction matters early, because it isn’t just descriptive. The favorite/underdog label also determines how a wager is priced: a winning bet on the favorite returns less profit per dollar risked than a winning bet on the underdog, because the favorite is judged more likely to actually happen. This article explains what the two terms mean, how a sportsbook assigns them, what a realistic example looks like, and the common ways bettors misread the labels — without walking through the full odds-to-probability math, which has its own dedicated guide.

What “Favorite” and “Underdog” Actually Mean

A favorite is the side of a matchup that a sportsbook’s odds imply is more likely to win. An underdog is the side the odds imply is less likely to win. Bettors sometimes use informal slang for the same idea — “chalk” for the favorite, “the dog” for the underdog — but the underlying concept is identical: one side is favored, the other is not. Neither label is a guarantee of anything — it is an expression of relative probability based on the information a sportsbook has at the time it sets the odds, not a statement about what will actually happen on the field, court, or ice.

The distinction is also always relative to a specific matchup, not a fixed property of a team. A team can be a heavy favorite against a weaker opponent one week and a clear underdog against a stronger opponent the next. There is no separate “favorites list” or “underdogs list” a team belongs to — the label is generated fresh for every game based on how the two sides compare for that particular matchup. This is a core piece of sports betting terminology because nearly every wager type — moneyline, point spread, and totals alike — is built around identifying which side is favored and by how much.

How Sportsbooks Assign the Labels

A sportsbook does not flip a coin to decide who is favored. Oddsmakers build an initial line using team and player data, matchup history, injuries, home-field or home-court advantage, and statistical models, then express the result as odds. In American odds format, the sign of the number is what signals the label — not the size of the number by itself. A negative number (such as -150) marks the favorite; a positive number (such as +130) marks the underdog. The number itself reflects how strong the favorite is judged to be or how big of an underdog the other side is, but it’s the sign that tells a bettor which side is which.

Once a line is posted, it rarely stays completely fixed. Sportsbooks adjust odds in response to where bettors are placing money and new information such as a late injury report or a lineup change. If enough money comes in on the underdog, a sportsbook may shorten that side’s odds (move it closer to even) and lengthen the favorite’s, though this is about balancing the book’s own risk, not a signal that the underdog has suddenly become more likely to win. The favorite/underdog labels can also appear alongside a point spread, where the favorite is assigned a negative number of points it must overcome and the underdog is given a positive number of points as a cushion — the same directional idea (negative signals favorite, positive signals underdog) carries over from the moneyline into that market.

It’s worth noting explicitly: this labeling mechanism is the sign convention itself, not the full conversion of odds into an implied probability percentage or a payout calculation. That conversion — the actual math behind the number — is covered in this blog’s dedicated guide to reading American odds, since it deserves its own full treatment.

A Favorite vs. Underdog Example

Suppose a sportsbook lists a hypothetical matchup between Team A and Team B. Team A is priced at -150 (the favorite) and Team B is priced at +130 (the underdog). The negative sign on Team A and positive sign on Team B are what identify each side’s role — Team A is expected to win more often than Team B in the sportsbook’s assessment.

Using a hypothetical $100 stake on each side: a $100 bet on Team A (-150) would return a profit of about $66.67 if it wins, for a total payout of $166.67 — profit is smaller because the favorite is more likely to win. A $100 bet on Team B (+130) would return a profit of $130 if it wins, for a total payout of $230 — a larger profit because the underdog is less likely to win. Either side can still lose; the odds describe likelihood, not a certainty. These numbers are illustrative examples only, not a real posted line.

Common Mistakes About Favorites and Underdogs

A frequent misconception is treating “favorite” as a synonym for “certain winner.” Being favored only means a sportsbook’s odds imply a higher likelihood of winning than the opponent — underdogs win often enough that upsets are a normal, expected part of every sport, not a rare fluke.

Another common error is confusing payout with profit. The payout on a winning bet always includes the original stake returned to the bettor; the profit is only the amount won on top of that stake. Describing a $166.67 payout as “$166.67 in winnings” overstates the actual profit by the size of the stake.

A third mistake is assuming underdog status says something permanent about a team’s overall quality. Because the label is generated per matchup, a strong team can still be an underdog against an even stronger opponent, and a weaker team can be a favorite in a more favorable matchup.

Where the Favorite/Underdog Label Matters at the Sportsbook

Every pre-game moneyline, point spread, and total a sportsbook posts is built around an implicit favorite/underdog designation, so recognizing the sign of the number is one of the first practical skills a new bettor needs before placing a wager. On a typical sportsbook board or bet slip, the favorite’s price is shown with a minus sign and the underdog’s with a plus sign, side by side for the same matchup, which makes the comparison easy to scan once a bettor knows what the signs mean.

This distinction directly shapes how a bettor should think about potential reward relative to risk: backing a favorite generally means risking more to win less, in exchange for a higher likelihood of winning, while backing an underdog means risking less to win more, in exchange for a lower likelihood of winning. Neither approach is inherently “better” — a favorite bet and an underdog bet are simply different trade-offs between likelihood and payout size, and the right choice depends on how a bettor actually assesses the matchup, not on a rule that one side is always the smarter play.

It’s also worth remembering that a sportsbook’s favorite/underdog assessment is a model, not a guarantee, and it can be wrong. Line movement, injury news, and public betting patterns can all shift the number after it’s first posted, which is exactly why treating any line — favorite or underdog — as a certainty rather than an estimate is a mistake worth avoiding from the very first bet a new bettor places.

Favorite and underdog labeling shows up most directly inside the moneyline — the simplest bet built entirely around picking a side to win outright. Bettors who are completely new to how a sportsbook prices a game can start with what a sportsbook is and how it sets odds, and the natural next step from here is learning to convert the odds themselves into implied probability and payout figures.

Frequently Asked Questions

Is it better to bet favorites or underdogs?

Neither is inherently better — they’re different trade-offs. Favorites offer a higher likelihood of winning but a smaller profit per dollar risked; underdogs offer a lower likelihood of winning but a larger profit if they do. Which fits a given bettor depends on how they assess the specific matchup, not a fixed rule favoring one side.

What happens if you bet on a favorite?

If the favorite wins, the bet pays out the stake plus a profit that’s smaller relative to the stake than an underdog bet would pay, because the favorite was judged more likely to win. If the favorite loses, the stake is lost, regardless of how strongly it was favored beforehand.

What do the plus and minus signs mean in betting odds?

In American odds, a minus sign marks the favorite and a plus sign marks the underdog. The sign identifies which side is which; the number after it indicates how strong that favorite or underdog status is, which is a separate calculation covered in this blog’s guide to reading American odds.

What does a +200 underdog mean?

The plus sign means that side is the underdog. On a hypothetical $100 stake, a +200 underdog that wins would return $200 in profit plus the original $100 stake, for a $300 total payout — reflecting that the sportsbook views this side as less likely to win than its opponent.

Can a team be a favorite in one game and an underdog in the next?

Yes. The favorite/underdog label is assigned fresh for every matchup based on how the two specific sides compare, not as a permanent status. A team can be a large favorite against a weaker opponent one week and a clear underdog against a stronger one the next.

Does being the underdog mean a team is worse overall?

Not necessarily. Underdog status reflects the sportsbook’s assessment for one specific matchup, which can be shaped by injuries, matchup style, or venue as much as overall team quality. A generally strong team can still be an underdog against a particular opponent it matches up poorly against.