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Français Odds are prices, not predictions
A betting price does two jobs at once: it tells you how much a winning bet returns, and it hints at how likely the bookmaker thinks the outcome is. Neither job is a promise. Odds of 1.50 do not mean a team will win — they mean the bookmaker is charging you a price that corresponds to roughly a 67% chance, minus its own commission.
Once you see odds as prices in a marketplace, a lot of betting logic clicks into place. Prices vary between bookmakers, they move as money and news arrive, and — like any market — some prices are simply wrong. Finding those is the whole game for serious bettors.
Decimal odds
Decimal odds are the default across Europe, Africa and most betting sites worldwide, and they are the easiest format to work with. The number is your total return per unit staked, stake included. Odds of 2.75 mean a winning €10 bet returns €27.50 — your €10 back plus €17.50 profit.
Two useful reflexes: anything below 2.00 is odds-on (the outcome is considered more likely than not), and the implied probability is simply 1 divided by the odds. 1 ÷ 2.75 ≈ 36.4%.
Fractional odds
Fractional odds (5/2, 11/10, 4/6) are the traditional UK and Ireland format. The fraction is profit relative to stake: 5/2 means €5 profit for every €2 staked, so a €10 bet at 5/2 returns €35 in total (€25 profit plus your stake).
To convert to decimal, divide the fraction and add 1: 5/2 → 2.5 + 1 = 3.50. Fractions below 1 (like 4/6) are odds-on favourites.
American odds
American odds come as positive or negative numbers anchored to a $100 stake. Negative (−150) shows how much you must stake to win $100: risk $150 to make $100 profit. Positive (+220) shows the profit on a $100 stake: risk $100 to make $220.
Conversion to decimal: for negative odds, 100 ÷ 150 + 1 = 1.67; for positive odds, 220 ÷ 100 + 1 = 3.20. If you mostly bet in decimal markets, converting American prices before comparing is worth the ten seconds it takes — our converter below does it instantly.
From odds to implied probability
Implied probability is the chance at which a price would be perfectly fair. For decimal odds the formula is 1 ÷ odds × 100. Odds of 1.50 imply 66.7%, odds of 3.00 imply 33.3%, odds of 10.0 imply 10%.
Add up the implied probabilities of every outcome in a market and you will get more than 100% — typically 103–108% in football. That extra slice is the bookmaker's margin, and it is why comparing prices across bookmakers matters: the same goal, priced at 1.90 in one shop and 2.02 in another, is a different bet.
Manchester City are 1.44 to beat Fulham, the draw is 4.80, Fulham are 7.50. Implied probabilities: 69.4% + 20.8% + 13.3% = 103.5%. The 3.5 points above 100 are the margin. If your own estimate of City's chances is higher than 69.4%, the 1.44 might be value; if lower, the price is against you no matter how likely a City win feels.
- Decimal odds = total return per unit staked; 1 ÷ odds = implied probability.
- Fractional odds show profit relative to stake; American odds anchor to a $100 stake.
- Every market's implied probabilities sum to more than 100% — the excess is the bookmaker's margin.
- The same outcome at different prices is a different bet: compare before you place.
Frequently asked questions
Which odds format should I use?
Whichever your market uses day to day — but learn to convert to decimal, because implied probability (1 ÷ odds) is easiest to compute there. Most sites let you switch formats in settings.
Do low odds mean a safe bet?
No. Odds of 1.20 imply about an 83% chance, which still loses roughly one time in six. Short-priced favourites lose often enough that no single bet is safe, and stacking them in accumulators compounds the risk.
Why do different bookmakers show different odds?
Each sets its own prices from its own model, liabilities and margin. Differences of 5–10% on the same outcome are common, which is why line shopping across several bookmakers is one of the few free improvements available to every bettor.