What does 10/11 mean in betting?

You win £10 for every £11 staked. £11 returns £21. It is decimal 1.91, American -110 and an implied probability of 52.4%.

You win £5 for every £2 staked. £10 returns £35 (£25 profit). It is decimal 3.50 and implies 28.6%.

Evens is 1/1: you win the same as you stake. Decimal 2.00, American +100, 50% implied probability.

How do I convert fractional odds to decimal?

Divide the first number by the second and add 1. 7/4 = 1.75 + 1 = 2.75.

Fractional odds explained: what 5/2 and 10/11 mean

By ProbaPredict Data Desk · Last reviewed Fri, 2 Oct 2026

Fractional odds show how much profit you win relative to your stake. 5/2 means you win £5 for every £2 staked, plus your stake back, so £10 returns £35. 10/11 means you win £10 for every £11 staked. When the first number is smaller, the price is odds-on; evens (1/1) doubles your money.

How do you read fractional odds?

Read the fraction as "win this much for staking that much". The first number is the profit, the second is the stake. At 5/2, a £2 bet wins £5 profit; at 1/4, a £4 bet wins £1 profit. You always get your stake back as well, so total return = stake × (first ÷ second) + stake.

What do common fractional odds mean?

1/2: win £1 per £2. Decimal 1.50, 66.7%.
4/6: win £4 per £6. Decimal 1.67, 60.0%.
10/11: win £10 per £11. Decimal 1.91, 52.4%.
Evens (1/1): decimal 2.00, 50%.
6/4: win £6 per £4. Decimal 2.50, 40%.
5/2: decimal 3.50, 28.6%.
4/1: decimal 5.00, 20%.

Why do bookmakers use odd-looking fractions like 10/11 and 4/6?

Fractional odds use a fixed ladder of traditional prices. Bookmakers pick the nearest step on that ladder. 10/11 exists because it sits just under evens, which is typical for a two-way market with a margin built in: if both sides are 10/11, each implies 52.4% and the total is 104.8%. That's why our odds converter shows the nearest common bookmaker fraction when a decimal price has no simple fraction.

How do you convert fractional odds?

To decimal: (first ÷ second) + 1. 5/2 → 3.50.
To implied probability: second ÷ (first + second). 5/2 → 2 ÷ 7 = 28.6%.
To American: if first ≥ second, +(first ÷ second × 100): 5/2 → +250. Otherwise −(second ÷ first × 100): 4/6 → -150.

Worked example: an Over 2.5 bet

A bookmaker offers Over 2.5 goals at 4/5 and Under 2.5 at evens. A £10 bet on Over returns £10 × 4 ÷ 5 + £10 = £18. Implied probabilities: Over 5 ÷ 9 = 55.6%, Under 1 ÷ 2 = 50.0%. Total 105.6%, so the margin is 5.6%. Removing it proportionally gives fair chances of 52.6% and 47.4%.

Our model might say Over 2.5 has a 54% chance, fair odds 100 ÷ 54 = 1.85 (about 17/20). The bookmaker's 4/5 is decimal 1.80, a little below our fair price, so it implies a slightly higher chance than we do.

How big is the margin in UK closing odds?

Here is the average margin in market closing odds in the leagues we cover. The Premier League has the lowest, at 4.4%.

Average bookmaker margin in closing odds, by league

League	Matches	1X2 margin	Over/Under 2.5 margin
Premier League	1,950	4.4%	4.9%
Bundesliga	1,566	4.8%	5.2%
La Liga	1,969	4.8%	5.2%
Serie A	1,950	4.9%	5.2%
Ligue 1	1,723	5.0%	5.3%
Championship	2,855	5.5%	5.6%
Eredivisie	1,593	5.7%	6.1%
Primeira Liga	1,592	6.2%	6.0%
Brasileirão Série A	2,177	6.3%	not in source

Source: ProbaPredict analysis of 17,375 matches, updated Fri, 2 Oct 2026. Market-average closing odds from football-data.co.uk. Margin = sum of implied probabilities − 100%.

UK and US terminology

UK and Ireland: fractional odds, "odds-on", "odds-against", "evens", "returns". US: American odds, "favorite", "underdog", "even money", "payout". 10/11 in the UK is -110 in the US.

Common mistakes with fractional odds

Forgetting the stake comes back. 2/1 returns three times your stake, not two.
Reading the fraction backwards. 1/4 (odds-on) is very different from 4/1.
Struggling to compare fractions. Is 8/13 shorter than 4/6? Convert both to decimal: 1.62 vs 1.67.
Multiplying fractions for an acca. Convert each leg to decimal first; our acca calculator does it for you.

Why do some bookmakers still use fractional odds?

Fractional odds grew up in British and Irish horse racing, where on-course bookmakers chalked prices on boards and bettors thought in terms of 'so much to one'. The format stuck for football in the UK and Ireland, and most bookmakers there still show fractions by default while letting you switch to decimal in your account settings. Many experienced bettors prefer decimal odds because the arithmetic is simpler, particularly for accumulators and for comparing prices; if you use fractions, the odds converter and acca calculator handle the conversions for you.

How do you work out returns on odds-on fractions?

The same formula applies: profit = stake × first ÷ second. At 4/9, a £9 stake wins £4 and returns £13. At 2/7, a £7 stake wins £2 and returns £9. For awkward stakes, it's easiest to convert to decimal first: 4/9 = 1.444, so £25 returns £36.11.

Odds-on fractions are common for big favourites and for markets like Over 1.5 goals. Converting them to implied probability is useful: 4/9 implies 9 ÷ 13 = 69.2%, and 2/7 implies 7 ÷ 9 = 77.8%. Compare that with our published probability on the match page to see whether the price implies more or less than our model does.

Frequently asked questions

What does 10/11 mean in betting?: You win £10 for every £11 staked. £11 returns £21. It is decimal 1.91, American -110 and an implied probability of 52.4%.
What does 5/2 mean?: You win £5 for every £2 staked. £10 returns £35 (£25 profit). It is decimal 3.50 and implies 28.6%.
What is evens?: Evens is 1/1: you win the same as you stake. Decimal 2.00, American +100, 50% implied probability.
How do I convert fractional odds to decimal?: Divide the first number by the second and add 1. 7/4 = 1.75 + 1 = 2.75.

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