Favorite vs Underdog

In any betting market with two or more possible outcomes, the favorite is the pick that oddsmakers think is most likely to win. It comes with lower odds (also called a shorter price), which means a smaller profit relative to your stake. The underdog is the pick seen as less likely to win. It comes with higher odds (a longer price), so a winning bet returns a bigger profit relative to what you risked.

Which side is the favorite and which is the underdog is decided entirely by the odds. In American format, the favorite shows a negative number (like -180) and the underdog a positive number (like +160). In decimal format, the favorite carries the lower value (1.56, for example) and the underdog the higher one (such as 2.60). Fractional odds work the same way: a shorter fraction like 4/7 marks the favorite, while a longer fraction like 8/5 marks the underdog.

It’s worth remembering that favorites don’t always come through. Upsets are a normal part of sports, and the odds only reflect probabilities, not guarantees. Sharp bettors look for spots where the market has overrated a favorite or underrated an underdog, because those mispricings are exactly where long-term profit comes from.

Example

In an upcoming boxing match, Fighter A is listed at -250 and Fighter B at +200. Fighter A is the favorite: you’d need to wager $250 to win $100 in profit. Fighter B is the underdog: a $100 bet returns $200 in profit if Fighter B wins.

If you think Fighter B has a better shot than the 33.3% implied by the +200 odds — say you put it at 40% — then backing the underdog might offer positive expected value even though Fighter B is the less likely winner.

Key Points

• Favorites have lower payouts, underdogs have higher payouts: This mirrors the probability assessment. More likely outcomes pay less; less likely outcomes pay more.
• The gap between the two indicates the expected competitiveness: A narrow gap between favorite and underdog odds points to a closely matched contest, while a wide gap signals a lopsided one.
• Favorites do not always win: Betting only on favorites isn’t a winning long-term plan, because the smaller payouts mean you need a very high win rate just to clear the juice.
• Value can exist on either side: The real question isn’t which side is the favorite but whether the odds fairly reflect the true probability. Mispriced favorites and underdogs both offer opportunities.
• Lines can shift: A team that opens as a slight underdog may turn into the favorite by game time as betting action and fresh news (injuries, weather, lineup changes) move the odds.