Fractional and decimal odds: the UK defaults
British betting traditionally uses fractional odds. A price of 5/2 means £5 profit for every £2 staked. Decimal odds show the total return instead: 5/2 becomes 3.50, meaning a £1 stake returns £3.50 if the bet wins.
| Fractional | Decimal | Profit on £10 | Total return |
|---|---|---|---|
| Evens / 1/1 | 2.00 | £10 | £20 |
| 6/4 | 2.50 | £15 | £25 |
| 5/2 | 3.50 | £25 | £35 |
| 4/1 | 5.00 | £40 | £50 |
| 10/11 | 1.91 | £9.09 | £19.09 |
How to convert fractional odds to decimal
Divide the numerator by the denominator, then add 1 for the returned stake.
Example: 7/2 → 7 ÷ 2 = 3.5 → add 1 = 4.50 decimal.
Implied probability
Odds can be converted into a break-even probability. With decimal odds, the formula is simple:
A price of 2.00 implies 50%. A price of 4.00 implies 25%. This is not a guarantee that the outcome will happen at that frequency; it is the probability embedded in the price before you account for the bookmaker margin.
The bookmaker margin / overround
In a two-outcome market, fair prices would add to 100% implied probability. Bookmaker prices typically add to more than 100%; the excess is commonly called the overround or margin.
If both sides of a market are priced at 10/11 (about 1.91 decimal), each implies roughly 52.4%. Together they total about 104.8%, so the excess over 100% is the basic market overround.
How each-way odds work
An each-way bet is really two bets of equal stake: one on the selection to win and one on it to place under the operator's published place terms. If you stake £5 each way, your total outlay is £10.
Place fractions and the number of paid places vary by race and promotion. Always read the market's place terms before confirming the bet rather than assuming the same fraction applies everywhere.
Why comparing odds matters
Small price differences compound over repeated betting. A selection at 5/2 returns more than the same selection at 12/5. Comparing several licensed operators before placing a bet is one of the few decisions entirely within the bettor's control.
For sports-specific examples, see our football betting guide and horse racing guide.
In-play prices and delays
In-play betting is legal in Great Britain. UKGC guidance notes that live pictures and data can involve latency, and operators may apply short bet-processing delays while prices update. A price shown on screen is therefore not always guaranteed until the wager is accepted.
Fast-moving live markets can encourage rapid repeat decisions. Set a stake budget before kick-off or race time rather than trying to recover losses during the event.
Odds FAQ
Are fractional odds better than decimal odds?
No. They represent the same price. Decimal odds are usually faster for calculating total return; fractional odds remain familiar in UK racing and football.
What does “evens” mean?
Evens means 1/1, equivalent to 2.00 decimal. A £10 winning stake returns £20 in total.
Do odds include the bookmaker's margin?
Usually yes. You can estimate it by converting every outcome into implied probability and adding the percentages.