LEARNODDS & PROBABILITY

How to Read American Betting Odds

−110, +150, and the arithmetic underneath American odds — how a price becomes a break-even rate.

2 MIN READ · BETTORWISE RESEARCH · EXAMPLES MARKED AS ILLUSTRATIVE

American odds answer one question: what does a winning bet pay? A negative number is a favorite: −110 means risk 110 to win 100. A positive number is an underdog: +150 means risk 100 to win 150. That’s the whole notation.

Every price is a break-even rate

−110 implies 52.4% — you must win more than 52.4 bets per 100 just to tread water. +150 implies 40.0%. Converting odds to implied probability is the first move in every serious comparison.

−110 → 110 / (110 + 100) = 52.4% · +150 → 100 / (150 + 100) = 40.0%

Why both sides can’t be fair

Price the same event at −110 on both sides and the implied probabilities sum to 104.8%. The extra is the bookmaker’s margin — the vig. Neither side, alone, is the market’s real opinion.

RELATED READING

01How Implied Probability Works

A price is a probability in disguise. Implied probability is the break-even rate hidden in the odds — the common language for comparing books, models and markets.

ODDS & PROBABILITY · 2 MIN02What Does No-Vig Mean?

Both sides of a market include a bookmaker’s margin. Remove it — de-vig the line — and the market’s real opinion appears.

ODDS & PROBABILITY · 2 MIN03Why −110 at One Sportsbook Is Not the Same as −120

Two almost-identical prices demand clearly different win rates. The pick is the same; the bet is not.

ODDS & PROBABILITY · 2 MIN

Compare the market yourself.

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