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By The Guv'nor · Last updated October 2026
Horse racing odds explained in one go: a price tells you what you'll win and how likely the bookmaker thinks your horse is to win. Fractional odds of 5/2 mean £5 profit for every £2 you stake, so a £10 bet returns £35: £25 profit plus your tenner back. In decimal that's 3.50, stake included.
That's the whole trick. I'm essentially a statistics/maths geek, so below you get the full chart, a real race's margin and a season of data on how often each price wins. Brand new to this? My beginner's guide to betting on horse racing is the place to start.
Fractional odds explained: how horse racing odds work, with £10 and €10
The left number is your profit and the right number is your stake. So 4/1 is £4 profit for every £1 staked, and 4/6 is £4 profit for every £6.
For any stake the sum is the same: profit = stake × left number ÷ right number. Add your stake back on and you've got your return.
- £10 at 5/2: £10 × 5 ÷ 2 = £25 profit, £35 back.
- €10 at 6/4: €10 × 6 ÷ 4 = €15 profit, €25 back.
- €10 at 4/6: €10 × 4 ÷ 6 = €6.67 profit, €16.67 back.
Left number bigger than the right (5/2) and you win more than you staked; smaller (4/6) and you win less.
What does 5/2 mean in horse racing?
5/2 (said "five to two") means you win £5 for every £2 you put on. It's the same as 2.5/1, or 3.50 in decimal odds. At 5/2 the bookmaker is pricing the horse as roughly a 28.6% chance, a bit better than one race in four.
Fractional odds to decimal, and back again
Decimal odds, as used on the Betfair exchange, show the total return for every £1 or €1 staked.
- Fraction to decimal: divide the left number by the right, then add 1. 5/2 is 2.5 + 1 = 3.50. 4/6 is 0.67 + 1 = 1.67.
- Decimal to fraction: take 1 off, then turn what's left into a fraction. 3.75 minus 1 is 2.75, which is 11/4. 1.50 minus 1 is 0.5, which is 1/2.
Decimal makes comparing prices easier at a glance. Is 15/8 bigger than 9/5? In decimal it's 2.88 against 2.80, so yes.
Horse racing odds chart: fraction, decimal, implied chance and return
Every common UK price from 1/10 to 100/1. Swap the £ for € and every figure stays the same.
| Fractional | Decimal | Implied chance | Profit on £10 | Total return on £10 |
|---|---|---|---|---|
| 1/10 | 1.10 | 90.9% | £1 | £11 |
| 1/8 | 1.13 | 88.9% | £1.25 | £11.25 |
| 1/6 | 1.17 | 85.7% | £1.67 | £11.67 |
| 1/5 | 1.20 | 83.3% | £2 | £12 |
| 2/9 | 1.22 | 81.8% | £2.22 | £12.22 |
| 1/4 | 1.25 | 80.0% | £2.50 | £12.50 |
| 2/7 | 1.29 | 77.8% | £2.86 | £12.86 |
| 1/3 | 1.33 | 75.0% | £3.33 | £13.33 |
| 4/11 | 1.36 | 73.3% | £3.64 | £13.64 |
| 2/5 | 1.40 | 71.4% | £4 | £14 |
| 4/9 | 1.44 | 69.2% | £4.44 | £14.44 |
| 1/2 | 1.50 | 66.7% | £5 | £15 |
| 8/15 | 1.53 | 65.2% | £5.33 | £15.33 |
| 4/7 | 1.57 | 63.6% | £5.71 | £15.71 |
| 8/13 | 1.62 | 61.9% | £6.15 | £16.15 |
| 4/6 | 1.67 | 60.0% | £6.67 | £16.67 |
| 8/11 | 1.73 | 57.9% | £7.27 | £17.27 |
| 4/5 | 1.80 | 55.6% | £8 | £18 |
| 5/6 | 1.83 | 54.5% | £8.33 | £18.33 |
| 10/11 | 1.91 | 52.4% | £9.09 | £19.09 |
| Evens (1/1) | 2.00 | 50.0% | £10 | £20 |
| 11/10 | 2.10 | 47.6% | £11 | £21 |
| 6/5 | 2.20 | 45.5% | £12 | £22 |
| 5/4 | 2.25 | 44.4% | £12.50 | £22.50 |
| 11/8 | 2.38 | 42.1% | £13.75 | £23.75 |
| 6/4 | 2.50 | 40.0% | £15 | £25 |
| 13/8 | 2.63 | 38.1% | £16.25 | £26.25 |
| 7/4 | 2.75 | 36.4% | £17.50 | £27.50 |
| 15/8 | 2.88 | 34.8% | £18.75 | £28.75 |
| 2/1 | 3.00 | 33.3% | £20 | £30 |
| 85/40 | 3.13 | 32.0% | £21.25 | £31.25 |
| 9/4 | 3.25 | 30.8% | £22.50 | £32.50 |
| 5/2 | 3.50 | 28.6% | £25 | £35 |
| 11/4 | 3.75 | 26.7% | £27.50 | £37.50 |
| 3/1 | 4.00 | 25.0% | £30 | £40 |
| 10/3 | 4.33 | 23.1% | £33.33 | £43.33 |
| 7/2 | 4.50 | 22.2% | £35 | £45 |
| 4/1 | 5.00 | 20.0% | £40 | £50 |
| 9/2 | 5.50 | 18.2% | £45 | £55 |
| 5/1 | 6.00 | 16.7% | £50 | £60 |
| 11/2 | 6.50 | 15.4% | £55 | £65 |
| 6/1 | 7.00 | 14.3% | £60 | £70 |
| 13/2 | 7.50 | 13.3% | £65 | £75 |
| 7/1 | 8.00 | 12.5% | £70 | £80 |
| 15/2 | 8.50 | 11.8% | £75 | £85 |
| 8/1 | 9.00 | 11.1% | £80 | £90 |
| 17/2 | 9.50 | 10.5% | £85 | £95 |
| 9/1 | 10.00 | 10.0% | £90 | £100 |
| 10/1 | 11.00 | 9.1% | £100 | £110 |
| 11/1 | 12.00 | 8.3% | £110 | £120 |
| 12/1 | 13.00 | 7.7% | £120 | £130 |
| 14/1 | 15.00 | 6.7% | £140 | £150 |
| 16/1 | 17.00 | 5.9% | £160 | £170 |
| 18/1 | 19.00 | 5.3% | £180 | £190 |
| 20/1 | 21.00 | 4.8% | £200 | £210 |
| 22/1 | 23.00 | 4.3% | £220 | £230 |
| 25/1 | 26.00 | 3.8% | £250 | £260 |
| 28/1 | 29.00 | 3.4% | £280 | £290 |
| 33/1 | 34.00 | 2.9% | £330 | £340 |
| 40/1 | 41.00 | 2.4% | £400 | £410 |
| 50/1 | 51.00 | 2.0% | £500 | £510 |
| 66/1 | 67.00 | 1.5% | £660 | £670 |
| 80/1 | 81.00 | 1.2% | £800 | £810 |
| 100/1 | 101.00 | 1.0% | £1,000 | £1,010 |
A few things jump out of that chart. Evens is the dividing line at 50%. Everything shorter than evens (10/11, 4/6, 1/2) is odds-on and needs to win more often than it loses just for you to break even. And the gaps between prices are much tighter at the short end: 6/4 to 13/8 is under two points of chance, while 50/1 to 100/1 halves it.
Odds-on, evens and the rest of the jargon
The price words you'll hear most:
- Odds-against: any price bigger than evens, like 2/1 or 11/4. You win more than you stake.
- Evens (1/1, or 2.00): you win the same as you stake. £10 on, £10 profit, £20 back.
- Odds-on: any price shorter than evens. In the Jockey Club's jargon guide it's the price of a strong favourite, where you make under £1 profit for every £1 staked. You'll sometimes hear 1/2 called "2/1 on", which is just the fraction said the other way round.
- Short price and long price: short means the market fancies the horse, so it pays relatively little; long (an outsider) means it doesn't, and a winner pays a multiple of your stake.
- Favourite and joint-favourite: the shortest-priced horse in the race. When two share it, the result shows JF.
- 100/30 and 10/3: the same price (4.33 in decimal), written two ways. You'll see both on results.
- SP: the Starting Price, the official odds at the off, and the price your bet is settled at if you didn't take a fixed price. Starting price explained covers SP against early prices, Best Odds Guaranteed and Betfair SP (BSP).
The rest of the slang, from jolly to steamer, is in my horse racing betting terms A to Z.
Implied probability and the overround in a real race
Every price is a percentage in disguise. The implied probability is the chance a price says the horse has of winning:
- From decimal odds: 1 ÷ decimal. 3.50 is 1 ÷ 3.5 = 28.6%.
- From fractional odds: right number ÷ (left + right). 5/2 is 2 ÷ 7 = 28.6%.
It's also your break-even line: a 5/2 shot has to win more than 28.6% of the time for the bet to make money over the long run.
Add up the implied chances of every runner in a race and a fair book would come to exactly 100%, because one of them has to win. A bookmaker's book always comes to more. The extra is the overround, and it's the bookie's margin baked into the prices.
Case study: the 2026 Cheltenham Gold Cup (past race)
Here's a real race from 13 March 2026. Ten ran (Spillane's Tower was a non-runner, so it's in neither book). I've set the official SPs, as published in the race result, against the Betfair SP for the same horses, taken from Betfair's own BSP price files.
| Horse (finish) | SP | SP implied chance | BSP | BSP implied chance |
|---|---|---|---|---|
| Gaelic Warrior (1st) | 11/4 JF | 26.7% | 4.10 | 24.4% |
| Jango Baie (2nd) | 11/4 JF | 26.7% | 3.95 | 25.3% |
| Inothewayurthinkin (3rd) | 11/1 | 8.3% | 13.60 | 7.4% |
| Grey Dawning (4th) | 16/1 | 5.9% | 21.00 | 4.8% |
| L'Homme Presse (5th) | 40/1 | 2.4% | 55.00 | 1.8% |
| Firefox (6th) | 25/1 | 3.8% | 25.36 | 3.9% |
| Gold Tweet (7th) | 100/1 | 1.0% | 172.72 | 0.6% |
| The Jukebox Man (8th) | 7/2 | 22.2% | 5.80 | 17.2% |
| Envoi Allen (9th) | 33/1 | 2.9% | 36.00 | 2.8% |
| Haiti Couleurs (pulled up) | 6/1 | 14.3% | 8.14 | 12.3% |
| Book total | 114.3% | 100.5% |
The SP book adds up to 114.3%, so roughly 14 points of margin are spread across ten horses. The Betfair book comes to 100.5%, close to fair, because the exchange takes its cut as commission on winnings instead of building it into the price.
In your pocket, with hindsight: £10 on the winner at SP returned £37.50, and at BSP £41.00 before commission. It isn't one-way traffic (Firefox's BSP of 25.36 was a touch shorter than its 25/1 SP), but across the race the exchange book was nearly 14 points tighter.
How to use the overround to spot overpriced horses is in my guide to value betting in horse racing.
How often horses at each price actually win
Does a horse win as often as its price says? I took one full season of UK and Irish racing, 12,991 races and 119,341 runners from 1 October 2025 to 30 September 2026, grouped every runner by its Betfair SP and compared how often each group was expected to win with how often it actually did.
| BSP band (fractional guide) | Runners (N) | Implied chance | Actual win rate | Likely range |
|---|---|---|---|---|
| 1.01 to under 2.00 (odds-on) | 2,113 | 61.8% | 60.3% | 58.2% to 62.4% |
| 2.00 to under 3.00 (evens to 2/1) | 4,584 | 40.0% | 39.7% | 38.3% to 41.1% |
| 3.00 to under 5.00 (2/1 to 4/1) | 12,350 | 25.4% | 25.6% | 24.9% to 26.4% |
| 5.00 to under 8.00 (4/1 to 7/1) | 17,754 | 15.9% | 16.0% | 15.5% to 16.6% |
| 8.00 to under 13.00 (7/1 to 12/1) | 18,977 | 10.0% | 9.8% | 9.3% to 10.2% |
| 13.00 to under 21.00 (12/1 to 20/1) | 17,238 | 6.2% | 6.3% | 5.9% to 6.6% |
| 21.00 to under 34.00 (20/1 to 33/1) | 13,649 | 3.9% | 4.0% | 3.7% to 4.3% |
| 34.00 to under 51.00 (33/1 to 50/1) | 9,011 | 2.4% | 2.6% | 2.3% to 3.0% |
| 51.00 to under 101.00 (50/1 to 100/1) | 9,511 | 1.4% | 1.4% | 1.2% to 1.7% |
| 101.00 and bigger (bigger than 100/1) | 14,154 | 0.42% | 0.39% | 0.30% to 0.51% |
The prices are scarily good. Odds-on shots won 60.3% of the time against an implied 61.8%. Runners between 2/1 and 4/1 won 25.6% against 25.4%. In all ten bands the implied chance sits inside the likely range, so none of the gaps is bigger than you'd expect from chance alone. Even beyond 100/1, where only 55 of 14,154 runners won, the price called it almost exactly.
Two caveats. This is Betfair SP, a near-fair market; bookmaker SPs carry the extra margin you saw in the Gold Cup, so their implied chances run a bit higher than reality. And it's one season, so the bands with few winners are noisy.
The lesson: the market is a very good judge on average, so you need a real reason to think it's wrong about a particular horse. That's why any AI horse racing prediction has to beat these prices, not just pick winners. For the favourite's side of the story, see how often favourites win.
Method, briefly: data from Betfair's free daily BSP files (UK and Irish win markets only; the two "to be placed" markets that turn up inside the UK win files are left out). Every runner counts, including those at Betfair's 1,000 price cap, and every race had a winner. Each band runs from its lower price up to, but not including, the next one. The 16 dead heats count as wins for both horses. "Implied chance" is the average of 1 ÷ BSP across the band.
Why I think in percentages, not fractions
Look, I used to be a Quantitative Researcher at a Tier 1 investment bank, so I'll admit I don't really see 11/4 when I look at a price. I see 26.7%. Then the only question that matters is whether I think the horse's chance is bigger than that.
Fractions hide how much a short price asks of a horse. 4/6 sounds safe as houses, but it has to win 60% of the time just for you to break even. That's why I focus on profit month to month, not win rate. Anyone can talk about high win rates when they tip odds-on horses all day, but what are you actually winning profit-wise? I'd much rather find an outsider whose real chance is bigger than its price, and with each-way value, even when they place we make more profit than an odds-on shot winning.
Percentages also keep you honest about losers: a 25% shot loses three times in four, however good the bet. Understanding that losers are a thing is the key to being a winner longer term. So I stake in points (1pt can be £5 on a £100 bank), I don't chase, and I never go all in because I've got a feeling. Trust the process.
In doubles and trebles the decimal prices simply multiply, which is where Lucky 15 explained picks up. My ten rules for doing all this properly are in my horse racing betting strategy guide.
- The Guv'nor
Odds questions punters ask
What does 11/4 mean in horse racing?
You win £11 for every £4 staked. £10 at 11/4 returns £37.50 (£27.50 profit plus your stake). In decimal it's 3.75, and it implies a 26.7% chance.
What does 10/11 mean?
It's a shade odds-on: £10 profit for every £11 staked, or 1.91 in decimal. It implies a 52.4% chance, and £10 at 10/11 returns £19.09.
More in this guide
- How to bet on horse racing: the beginner's guide
- Starting price (SP) explained, with BOG and Betfair SP
- Each-way betting explained, with place terms and the maths
- Rule 4 deductions: the full table
- Horse racing betting terms A to Z
I run Bolts Up Daily. I was a Quantitative Researcher at a Tier 1 Investment Bank (essentially a statistics and maths geek), and I now use those skills to analyse UK and Irish racing, profitably enough that most of your favourite bookies won't take a bet from me. Every horse I tip, I'm betting on myself, and every bet comes with a stake in points. I own racehorses too. Look, I can't guarantee every tip is going to win (anyone that can is a fraudster), but I care about profit, not strike rate.
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