Favorite vs Underdog

In any betting market with two or more possible outcomes, the favorite is the selection that oddsmakers consider most likely to win. It carries lower odds (also called a shorter price), meaning you receive less profit relative to your stake. The underdog is the selection considered less likely to win. It carries higher odds (a longer price), meaning a successful bet returns a larger profit relative to the amount risked.

The designation of favorite and underdog is determined entirely by the odds. In American format, the favorite is identified by a negative number (such as -180) and the underdog by a positive number (such as +160). In decimal format, the favorite has the lower value (for example, 1.56) and the underdog the higher value (for example, 2.60). Fractional odds follow the same logic — a shorter fraction like 4/7 represents the favorite, while a longer fraction like 8/5 represents the underdog.

It is important to recognize that favorites do not always win. Upsets are a regular part of sports, and the odds merely reflect probabilities — not certainties. Skilled bettors look for situations where the market has overvalued a favorite or undervalued an underdog, because those mispricings are where long-term profit is found.

Example

In an upcoming boxing match, Fighter A is listed at -250 and Fighter B at +200. Fighter A is the favorite: you would 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 believe Fighter B has a better chance than the 33.3% implied by the +200 odds — say, you estimate a 40% chance — then betting the underdog may offer positive expected value despite Fighter B being the less likely winner.

Key Points

• Favorites have lower payouts, underdogs have higher payouts: This reflects the probability assessment. More likely outcomes pay less; less likely outcomes pay more.
• The gap between the two indicates the expected competitiveness: A narrow spread between favorite and underdog odds suggests a closely matched contest, while a wide gap signals a lopsided matchup.
• Favorites do not always win: Betting exclusively on favorites is not a winning long-term strategy because the reduced payouts mean you need a very high win rate to overcome the juice.
• Value can exist on either side: The key question is not which side is the favorite but whether the odds accurately reflect the true probability. Mispriced favorites and underdogs both present opportunities.
• Lines can shift: A team that opens as a slight underdog may become the favorite by game time as betting action and new information (injuries, weather, lineup changes) move the odds.