How to Read Betting Odds (Decimal, Fractional & American)

Odds look like jargon, but they're really just a probability with a price attached. Once you can convert any odds format into an implied percentage, the whole game gets clearer — and you can start spotting when a price is too generous.

Decimal odds (the easiest)

Used across Europe and by sharp books. Decimal odds = your total return per unit staked. Odds of 2.00 return €2 for every €1 (your €1 stake plus €1 profit). 1.50 returns €1.50; 4.00 returns €4. To get the implied probability, just divide 1 by the odds: 1 / 2.00 = 50%, 1 / 4.00 = 25%.

Fractional odds (UK)

Common in Britain and horse racing. 5/1 ("five to one") means €5 profit per €1 staked — equivalent to decimal 6.00. The conversion: decimal = (numerator ÷ denominator) + 1. So 5/1 → 6.00, 6/4 → 2.50, 1/2 → 1.50. Implied probability = denominator ÷ (numerator + denominator): 5/1 → 1/6 ≈ 16.7%.

American odds (moneyline)

Used in the US. Positive numbers show profit on a 100 stake (+150 = €150 profit per €100, decimal 2.50). Negative numbers show how much you must stake to win 100 (−200 = stake €200 to win €100, decimal 1.50). Fiddly — which is why a converter helps. Our free odds converter handles all three formats and the probability instantly.

Why the percentages add up to more than 100%

Add the implied probabilities of every outcome in a market and you'll get more than 100% — that excess is the bookmaker's built-in margin (the "vig"). It's why the displayed odds slightly understate the true chances, and why beating them takes a genuine edge. We unpack that fully in how bookmakers set their odds.

From reading odds to beating them

Reading odds is step one. The next step is comparing the implied probability to a more accurate one — what value betting is all about. When your estimated probability beats the odds' implied probability, you've found value.