Odds tell you two things at once: how much a bet pays, and how likely the bookmaker thinks it is. Once you can read both, you can compare prices, spot the margin and judge whether a bet is worth it.

Decimal Odds

The format used across Europe and by many crypto sportsbooks. The number is the total return per unit staked, including your stake.

  • 2.00: a $10 bet returns $20 (your $10 + $10 profit).
  • 1.50: a $10 bet returns $15 ($5 profit).
  • 4.00: a $10 bet returns $40 ($30 profit).

Fractional Odds

Traditional in the UK. The fraction is profit over stake.

  • 1/1 (evens): win $10 on a $10 bet. Same as 2.00 decimal.
  • 5/2: win $25 on a $10 bet. Same as 3.50 decimal.
  • 1/2: win $5 on a $10 bet. Same as 1.50 decimal.

To convert to decimal: divide the fraction and add 1. 5/2 = 2.5, plus 1 = 3.50.

American Odds

Common in the US, written with a plus or minus sign.

  • Positive (+150): the profit on a $100 bet. +150 means $150 profit, or 2.50 decimal.
  • Negative (-200): the stake needed to win $100. -200 means you bet $200 to win $100, or 1.50 decimal.

Implied Probability

Every price hides a probability. For decimal odds:

Implied probability = 1 / decimal odds

  • 2.00 implies 50%.
  • 4.00 implies 25%.
  • 1.25 implies 80%.

The Bookmaker's Margin

Add up the implied probabilities of every outcome of a match and you get more than 100%. The extra is the bookmaker's margin.

Example. A football match priced 2.10 home, 3.40 draw, 3.60 away:

  • 1/2.10 = 47.6%
  • 1/3.40 = 29.4%
  • 1/3.60 = 27.8%
  • Total: 104.8%, so the margin is 4.8%.

The lower the margin, the fairer the price. Our Stake odds page shows the margin on every Champions League and tennis match.

When Is a Price Good Value?

A bet has value when your own estimate of the chance is higher than the implied probability. If you think a team wins 55% of the time and the odds imply 45%, the price is in your favour. That depends entirely on your estimate being better than the bookmaker's, which is hard to do consistently.

Odds Move

Prices change as news arrives and money comes in. Odds you see now may be different when you place the bet, so always check the price on the slip before confirming.

Whatever the format, decide your stake first and keep it within your budget: see bankroll management.