Two ways to show the same price
Decimal and fractional odds are different ways of displaying a betting price. Both tell you how much a winning bet would pay, but they present that information differently.
Decimal odds show your total return, including your stake. Fractional odds show your profit relative to your stake.
Understanding that difference makes it easier to compare prices and avoid confusing a payout with a profit. Neither format makes a bet more likely to win.
What are decimal odds?
Decimal odds are written as numbers such as 1.50, 2.00 or 3.75. To calculate the total return on a winning bet, multiply your stake by the odds:
Total return = stake × decimal odds
Then subtract your original stake to find the profit:
Profit = total return − stake
For example, suppose you place £10 on a team to win at decimal odds of 2.50:
- Total return: £10 × 2.50 = £25
- Original stake: £10
- Profit: £25 − £10 = £15
If the bet loses, you lose the £10 stake. The £25 return applies only if it wins.
Lower decimal odds mean a smaller potential return for the same stake. They also represent a higher implied probability, which we will explain below.
What are fractional odds?
Fractional odds are written as 1/2, 1/1 or 3/1. They are common in UK betting coverage.
The first number tells you the potential profit for every amount staked shown by the second number.
At 3/1, you make £3 profit for every £1 staked if your bet wins. At 1/2, you make £1 profit for every £2 staked.
The calculation is:
Profit = stake × (first number ÷ second number)
For a £10 winning bet at 3/2:
- Profit: £10 × (3 ÷ 2) = £15
- Total return: £15 + £10 stake = £25
That is exactly the same payout as decimal odds of 2.50. Only the display has changed.
Fractional odds of 1/1, also called “evens”, are equivalent to decimal odds of 2.00.
How to convert fractional odds to decimal
Divide the first number by the second, then add one:
Decimal odds = (first number ÷ second number) + 1
The extra one represents the return of your original stake.
For example, to convert 7/4:
- Divide 7 by 4 to get 1.75.
- Add 1 to get 2.75.
Here are a few useful equivalents:
| Fractional odds | Decimal odds | |---|---:| | 1/2 | 1.50 | | 4/5 | 1.80 | | 1/1 | 2.00 | | 3/2 | 2.50 | | 7/4 | 2.75 | | 3/1 | 4.00 |
How to convert decimal odds to fractional
Subtract one from the decimal odds, then express the result as a fraction in its simplest form:
Fractional odds = decimal odds − 1
For example, with decimal odds of 3.25:
- Subtract 1: 3.25 − 1 = 2.25.
- Write 2.25 as a fraction: 225/100.
- Simplify it to 9/4.
Some decimal prices produce less familiar fractions. Decimal odds of 1.91, for instance, convert exactly to 91/100. A betting interface may use a rounded equivalent, so check the actual price when comparing returns.
What is implied probability?
Implied probability translates an odds price into a percentage. It shows the probability suggested by that price, not a guaranteed or independently measured chance of winning.
For decimal odds:
Implied probability = (1 ÷ decimal odds) × 100
At 2.50, the calculation is:
(1 ÷ 2.50) × 100 = 40%
For fractional odds written as a/b, use:
Implied probability = b ÷ (a + b) × 100
At 3/2, that becomes:
2 ÷ (3 + 2) × 100 = 40%
For a straightforward win-or-lose bet, that percentage is also the break-even win rate at those odds, before any fees or taxes. It does not mean the team’s true chance is 40%. The price alone cannot establish that.
Why bookmaker margin matters
In a market covering every possible outcome, with no overlap, fair probabilities would add up to 100%. Bookmakers generally offer prices whose implied probabilities total more than 100%.
The excess is called the overround, a common way to describe the margin built into the prices.
Consider this hypothetical football match market for the result after normal time:
| Outcome | Decimal odds | Implied probability | |---|---:|---:| | Home win | 2.00 | 50.00% | | Draw | 3.50 | 28.57% | | Away win | 4.00 | 25.00% | | Total | | 103.57% |
The overround is 3.57 percentage points above 100%.
This is why you should not treat each displayed implied probability as a fair estimate. The prices collectively include a bookmaker cushion. Overround is not the bookmaker’s guaranteed profit rate: actual results depend on the stakes taken and which outcomes occur.
You can divide each implied probability by the total to make them sum to 100%. That provides a simple margin-adjusted estimate, but assumes the margin is spread proportionally. It does not reveal the true probabilities.
What to remember when comparing odds
For the same selection and settlement rules, higher decimal odds mean a larger return if the bet wins. Always check whether a football market covers normal time only or includes extra time and penalties.
Use odds to understand the price, not as proof that a prediction is correct. Even a market with a small margin can offer a poor price on a particular outcome.
Responsible gambling: Betting involves the risk of losing money. Only stake what you can afford to lose, set limits, and never chase losses. If gambling causes stress or financial pressure, stop and seek support.