Every price on every board says two things: how likely the book thinks it is, and what you get paid if you are right. Here is how to read both.
Every price on a betting board does two jobs at once. It tells you what you get paid if you are right, and it tells you how likely the sportsbook thinks you are to be right. Those are the same number written one way, and once you can read it, the rest of betting stops looking like code.
There are three formats in common use. American odds dominate in the United States, decimal odds nearly everywhere else, and fractional odds survive in the UK and in horse racing. They say identical things.
An American price is a number with a sign, and the sign tells you which side of $100 you are on.
The minus side is the favorite: cheaper to be right about, so it pays less. The plus side is the underdog: less likely, so it pays more. +100 is even money — the two sides are level.
You do not have to bet $100. The price is a ratio, not an instruction. A $25 bet at -150 risks $25 to win $16.67, because the ratio is the same all the way down.
Decimal odds are the total return per $1 staked, stake included. That last part is where people trip up: 2.50 returns $2.50 for every dollar, which is $1.50 of profit and your dollar back.
All three describe a bet that turns $100 into $250. Nothing about the bet changed.
Decimal is the easiest format to do arithmetic in, which is why every calculator in this section converts to it internally. Payout is just stake × decimal.
A fraction is profit over stake. 3/2 — read "three to two" — pays $3 profit for every $2 risked. 10/11 pays $10 for every $11, which is the fractional way of writing -110.
Anything where the first number is bigger than the second is an underdog. 1/4 is a heavy favourite; 20/1 is a longshot.
| American | Decimal | Fractional | $100 returns |
|---|---|---|---|
| -200 | 1.50 | 1/2 | $150.00 |
| -150 | 1.67 | 2/3 | $166.67 |
| -110 | 1.91 | 10/11 | $190.91 |
| +100 | 2.00 | 1/1 | $200.00 |
| +150 | 2.50 | 3/2 | $250.00 |
| +300 | 4.00 | 3/1 | $400.00 |
You will rarely need to do this by hand — but the conversion is worth seeing once, because everything in the next lesson is built on it.
-400 implies about an 80% chance. That is not a certainty — it is a bet that loses one time in five, and one time in five is not rare. A run of three of them in a month is completely ordinary.
The price is the market's opinion, expressed as a number. Whether that opinion is right — and whether the price you are being offered is fair for it — is the subject of the next several lessons.
Every price in this lesson, live across a dozen sportsbooks at once. Open the Odds Board.