Guide
How football odds work
A decimal price is a probability with a profit margin added. Divide one by the price to get the probability the bookmaker is charging you for; the three 1X2 prices deliberately add up to more than 100%, and the excess is the margin.
Published 2026-09-01 · Last reviewed 2026-09-01 · BetBuddy editorial
Reading a decimal price
Decimal odds state the total return per unit staked, stake included. A €10 bet at 2.50 returns €25.00: €15.00 profit plus the €10 back. Below 2.00 is odds-on, above 2.00 is odds-against.
total return = stake × odds profit = stake × (odds − 1)
Converting to other formats
Fractional and American odds describe the same thing in different units. Decimals are used throughout this site because every staking formula takes them directly, with no conversion rounding.
- Fractional → decimal: 5/2 becomes (5 ÷ 2) + 1 = 3.50
- Decimal → fractional: 3.50 becomes 3.50 − 1 = 2.5, i.e. 5/2
- Decimal → American, price above 2.00: (odds − 1) × 100, so 3.50 → +250
- Decimal → American, price below 2.00: −100 ÷ (odds − 1), so 1.80 → −125
Implied probability and break-even
The implied probability is the strike rate at which a price breaks even. Bet 1.80 repeatedly and you need to win 55.6% of the time simply to stand still.
implied probability = break-even probability = 1 / odds
| Decimal odds | Implied / break-even probability | Profit per €10 win |
|---|---|---|
| 1.50 | 66.7% | €5.00 |
| 1.80 | 55.6% | €8.00 |
| 2.00 | 50.0% | €10.00 |
| 2.50 | 40.0% | €15.00 |
| 3.50 | 28.6% | €25.00 |
The overround, and how to strip it out
Take a 1X2 market priced 2.10 / 3.40 / 3.60. The implied probabilities are 47.6%, 29.4% and 27.8% — 104.8% in total. That 4.8% excess is the overround: the bookmaker's built-in margin.
Comparing a model against raw implied probability therefore understates the edge on every selection. Dividing each implied probability by the book total gives the fair, margin-free probability: the home win becomes 47.6 ÷ 104.8 = 45.4%.
fair probability = implied probability / Σ implied probabilities
Common football markets
Most volume sits in a handful of markets, and they are the ones with the tightest margins and the most reliable prices.
- 1X2: home win, draw, away win over 90 minutes plus stoppage time.
- Over/Under total goals: the 2.5 line is the most traded; the half-goal prevents a tie.
- Both teams to score: settles on each side scoring at least once.
- Double chance and draw no bet: the same 1X2 probabilities repackaged at shorter prices.
Odds are not forecasts
A price is a market's aggregated opinion plus a margin plus whatever the bookmaker's own liability position demands. It is usually the best single estimate available, which is why beating it consistently is hard — but it is an estimate, not a measurement.
Prices also move. How and why they move is covered in the odds-movement guide.