Understanding football odds

The Three Main Odds Formats

Football odds come in three main formats: decimal, fractional, and American. All three represent the same underlying probability; they just express it differently.

Decimal Odds

Decimal odds are the most straightforward. They show your total return per unit staked. If the odds are 2.50 and you bet 10, your total return is 10 x 2.50 = 25 (15 profit + 10 stake). Decimal odds are used across Europe and increasingly worldwide.

To calculate implied probability from decimal odds: probability = 1 / odds. So 2.50 implies a 40% probability (1/2.50 = 0.40).

Fractional Odds

Fractional odds are traditional in the UK. They show profit relative to stake. Odds of 3/1 (pronounced "three to one") mean you win 3 for every 1 staked. Odds of 1/2 ("two to one on") mean you win 1 for every 2 staked.

To convert fractional to decimal: divide the fraction and add 1. So 3/1 = (3/1) + 1 = 4.00 decimal. And 1/2 = (1/2) + 1 = 1.50 decimal.

American Odds

American odds use positive and negative numbers. Positive odds (e.g. +150) show how much profit you make on a 100 stake. Negative odds (e.g. -200) show how much you need to stake to win 100.

To convert to decimal: if positive, divide by 100 and add 1 (+150 = 2.50). If negative, divide 100 by the absolute value and add 1 (-200 = 1.50).

Understanding Implied Probability

Every set of odds implies a probability. This is the bookmaker's assessment of how likely each outcome is, with their margin built in. If you believe the true probability is higher than the implied probability, you have found a value bet.

Use our Odds Converter to switch between formats and see implied probabilities instantly.

Odds in Accumulators

In an accumulator, decimal odds multiply together. This is the simplest way to understand combined odds. Three legs at 1.80, 2.00, and 1.50 give combined odds of 1.80 x 2.00 x 1.50 = 5.40. This is why decimal is the preferred format for acca calculations.