Favorite vs Underdog

In any market with two or more possible outcomes, the favorite is the selection oddsmakers rate most likely to win. It carries lower odds (a shorter price), meaning you collect less profit relative to your stake. The underdog is the selection rated less likely to win. It carries higher odds (a longer price), meaning a winning bet returns more profit relative to the amount risked.

The favorite and underdog labels are fixed entirely by the odds. In American format, the favorite is marked by a negative number (such as -180) and the underdog by a positive number (such as +160). In decimal format, the favorite holds the lower value (for example, 1.56) and the underdog the higher value (for example, 2.60). Fractional odds obey the same logic: a shorter fraction like 4/7 denotes the favorite, while a longer fraction like 8/5 denotes the underdog.

It is worth stressing that favorites do not always win. Upsets are a routine feature of sport, and the odds merely encode probabilities, not certainties. Skilled bettors hunt for spots where the market has overvalued a favorite or undervalued an underdog, because those mispricings are where long-term profit lives.

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 stake $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’s chances exceed the 33.3% implied by the +200 odds, say you estimate 40%, then backing the underdog may carry positive expected value despite Fighter B being 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 spread 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 exclusively on favorites is not a winning long-term strategy, because the reduced payouts demand a very high win rate just 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 turn into the favorite by game time as betting action and fresh information (injuries, weather, lineup changes) move the odds.