Every matchup has a favorite and an underdog. The favorite is the side the market expects to win, and the underdog is the side expected to lose. But "expected" is doing a lot of work in that sentence. Understanding what the odds really say about each side helps you make better decisions, and avoid the most common beginner habits.
How to spot each side
American odds:
- Favorite has a minus sign: -180
- Underdog has a plus sign: +155
Decimal odds:
- Favorite is below 2.00: 1.56
- Underdog is above 2.00: 2.55
Point spread:
- Favorite gives points: -5.5
- Underdog gets points: +5.5
When two teams are very close, both may show small minus prices, like -110 and -110. That is a pick'em or near-coin-flip game.
What the prices mean
Turn the prices into implied probability (see implied probability).
Example:
- Favorite -180 → 180 ÷ 280 = 64.3%
- Underdog +155 → 100 ÷ 255 = 39.2%
After removing the margin, the market sees roughly a 62/38 split. That does not mean the underdog has "no chance". It means they win about 38 times out of 100 in games like this.
Payout comparison
Worked example with a 100 stake:
| Pick | Odds | Win probability (fair) | Profit if win | |---|---|---|---| | Favorite | -180 | ~62% | 55.56 | | Underdog | +155 | ~38% | 155 |
Over 100 identical games at those fair probabilities:
- Favorite: 62 × 55.56 − 38 × 100 = 3,444 − 3,800 = -356
- Underdog: 38 × 155 − 62 × 100 = 5,890 − 6,200 = -310
Both lose a little, because both prices include the house margin. Neither side is automatically better. The question is always whether your probability estimate beats the price.
The favorite trap
Beginners often love favorites. They win more often, and winning feels good. But:
- Favorites pay less, so each loss hurts more.
- Heavy favorites (like -300 or shorter) need to win 75% or more just to break even.
- Popular favorites can be slightly overpriced because so many casual fans pick them.
A team at -400 that loses one game in five is a bad pick in the long run, even though it wins most of the time.
The underdog trap
Others love underdogs for the big payouts. But:
- Underdogs lose more often, which means longer losing runs.
- Long shots at +500 or bigger tend to carry a larger built-in margin than you might expect. This tendency is known as the favorite-longshot bias, observed in many betting markets: very long odds are often priced slightly worse than their true chances.
- Big payouts are memorable, so people overestimate how often they come in.
Why underdogs win more than people think
Sports are full of randomness. A bounce of the ball, a missed call, a hot shooting night. Upsets happen in every league, every week. In lower-scoring sports like soccer and hockey, even big favorites lose surprisingly often because one goal can decide a game. See why upsets happen.
How sport affects the gap
- NFL: Single games, big variance. Underdogs win plenty.
- NBA: Many possessions per game, so the better team wins more consistently. Big favorites rarely lose.
- MLB: Even the best teams lose a lot of games, so moneylines rarely go beyond -250 or so, except in special pitching matchups.
- NHL: Lots of parity and randomness, with moneylines often clustered close to even.
- Soccer: Draws matter. A favorite at 1.60 might only win 55% to 60% of the time, with the draw taking a big share.
How to think about it
Instead of asking "who will win?", ask:
- What does the price imply?
- What do I honestly think the chances are?
- Is the gap big enough to matter?
If you think a +155 underdog wins 45% of the time, that is a strong opinion against the market. Be honest about whether you have a real reason, like injury news the market has not priced in, or just a feeling. See value betting.
Practice both sides
A useful exercise on MockSport: for a week, make free play-money picks and note whether each was a favorite or underdog. At the end, compare your results. Many people find they win more often on favorites but end up with a better token balance on well-chosen underdogs, or the opposite. Either way, you learn something about your own tendencies. Start on the odds page.
FAQ
Is it better to pick favorites or underdogs?
Neither is better in general. What matters is whether the price is better than the real chance of winning. Both sides include a margin for the house.
What is a heavy favorite?
Usually a team priced at -300 or shorter (decimal 1.33 or lower), implying around a 75% chance or more of winning.
Why do underdogs pay more?
Because they are less likely to win. The bigger payout compensates for the lower probability.