Underdog

In sportsbetting the underdog is the side of a betting market that has a smaller perceived chance of winning. Often abbreviated dog, the underdog carries a positive point spread and yields a plus money return on the moneyline. The other side of the same market with a greater perceived chance of winning is known as the favorite.

Underdog moneyline

As underdogs are perceived as having a lower chance of winning relative to the favorite their moneyline yields a larger return. American odds format displays underdog moneylines with positive numbers. A team with +200 odds of winning carries a 33.3% implied probability and yields a $200 profit on a $100 initial risk (for a total return of $300).

In the example below the Baltimore Ravens are the underdog. They have +160 moneyline odds which carry a 38.5% implied probability. A $100 initial risk would yield a $160 profit for a total return of $260.

Team		Spread	Total	Moneyline
	New England Patriots	-3.5 (-110)	Over 44.5 (-110)	-180
	Baltimore Ravens	+3.5 (-110)	Under 44.5 (-110)	+160

Underdog spread

In order to balance the perceived skill discrepancies between competing teams a point spread is used. The underdog being viewed as the weaker team is given a positive spread. The points they are given are applied to the final score in order to determine if the bet wins. A bet on an underdog's point spread will win if they either win outright or lose by a margin smaller than the spread.

Using the same example as before the Baltimore Ravens have a +3.5 point spread with -110 odds. A bet on the Ravens spread would win if they either win the game outright or lose by 1-3 points. Because the point spread is being used to balance the perceived ability of both teams the betting odds are normally equal around -110. This means a $110 risk would yield $100 profit for a total return of $210.

Team		Spread	Total	Moneyline
	New England Patriots	-3.5 (-110)	Over 44.5 (-110)	-180
	Baltimore Ravens	+3.5 (-110)	Under 44.5 (-110)	+160