How to Read Betting Odds
Betting odds tell you two things at once: how likely an outcome is, and how much you'd win if it happens. Once you can read them, the rest of betting gets a lot clearer. There are three common formats — American, decimal, and fractional — and they all describe the same thing in different ways.
American odds (+150 / −110)
Used mainly in the United States, American odds are built around a $100 baseline and use a plus or minus sign.
- Minus (−) means the favorite. The number is how much you must stake to win $100. At −150, you bet $150 to win $100.
- Plus (+) means the underdog. The number is how much you win on a $100 stake. At +150, a $100 bet wins $150.
So the bigger a minus number, the heavier the favorite; the bigger a plus number, the longer the underdog. A line of −110 — extremely common on point spreads — means you risk $110 to win $100. That extra $10 is the sportsbook's cut, often called the "juice" or "vig."
Decimal odds (2.50)
Popular in Europe, Australia, and Canada, decimal odds are the simplest to calculate. The number is your total return per $1 staked, including your stake back.
- 2.50 means a $10 bet returns $25 total ($15 profit + your $10 back).
- Anything above 2.00 is an underdog; below 2.00 is a favorite; 2.00 is an even-money bet.
Fractional odds (3/2)
Traditional in the UK and Ireland, fractional odds show profit relative to stake. 3/2 means you win $3 for every $2 staked (plus your stake back). 1/2 means you win $1 for every $2 staked — a favorite.
The same odds, three ways
| American | Decimal | Fractional | Implied probability |
|---|---|---|---|
| −200 | 1.50 | 1/2 | 66.7% |
| −110 | 1.91 | 10/11 | 52.4% |
| +150 | 2.50 | 3/2 | 40.0% |
| +300 | 4.00 | 3/1 | 25.0% |
Implied probability — the most useful part
Every set of odds contains an implied probability: the chance the outcome happens according to the price. For decimal odds, it's simply 1 ÷ decimal odds. Decimal 2.50 → 1 ÷ 2.50 = 40%. If you think the real chance is higher than the implied probability, the bet has value; if lower, it doesn't. That comparison is the whole game.
You'll notice the implied probabilities in a matchup add up to more than 100% — that overage is the sportsbook's built-in margin (the vig again).
Switch formats freely on LineScout
If a format feels unnatural, you don't have to do the math in your head. LineScout lets you flip every price between US (American), EU (decimal), and UK (fractional) with one click, so you can read odds the way you're used to. See live odds →