Horse racing odds explained: what the prices mean

What does 5/2 mean in horse racing?

5/2 means you win £5 for every £2 you stake, plus your stake back, so a £10 bet at 5/2 returns £35: £25 profit and the £10 stake.

Fractional odds put profit on the left and stake on the right. At 5/1 you win £5 for every £1, at 7/2 you win £7 for every £2, and at 100/30 you win £100 for every £30. The same price in decimal form includes the stake, so 5/2 is 3.5: multiply your stake by 3.5 to get the total return.

Commentators read prices aloud in a set way: 5/2 is five to two, 11/4 is eleven to four and 100/30 is one hundred to thirty. Evens, written Evs or 1/1, means a winning bet doubles your money.

What is the difference between odds-on, evens and odds-against?

Odds-on means the profit is smaller than the stake, as at 4/6; evens means profit equals the stake; and odds-against means the profit is bigger than the stake, as at 5/2 or 10/1.

A horse at 4/6 is expected to win more often than not, and £6 staked wins £4 profit. Short-priced favourites are often odds-on in small fields. Odds-against covers almost every other runner, from a 6/4 favourite in a competitive race to a 100/1 outsider. When a bookmaker says odds-on, the horse's implied chance is above one in two.

How do you work out winnings from fractional odds?

Divide the stake by the right-hand number, multiply by the left-hand number to get the profit, then add the stake back to get the total return.

For £10 at 11/4: £10 divided by 4 is £2.50, times 11 is £27.50 profit, plus the £10 stake gives £37.50. For £20 at 4/6: £20 divided by 6 is £3.33, times 4 is £13.33 profit, returning £33.33. With decimal odds it is quicker: multiply the stake by the decimal price, so £10 at 3.75 returns £37.50.

Each way bets, Rule 4 deductions and dead heats change the calculation. An each way bet is two bets, a Rule 4 reduces the winnings when a horse is withdrawn late, and a two-way dead heat halves the stake at the full price, so a bet calculator is useful for anything beyond a single win bet.

Why do racing odds use fractions like 100/30 and 13/8?

Racing odds follow a traditional ladder of prices built up by bookmakers over centuries, so between 6/4 and 2/1 you find 13/8, 7/4 and 15/8 rather than neat decimals, and 100/30 sits between 3/1 and 7/2.

The ladder gives bookmakers small steps to shorten or lengthen a horse's price as money comes in. 100/30 is simply ten to three written with bigger numbers, and prices such as 85/40 fill the gap between 2/1 and 9/4. Once you know the ladder, a move from 7/2 to 3/1 to 11/4 is easy to read as a horse being backed, and the reverse as a drifter.

What chance of winning does a horse racing price imply?

Every price implies a chance: divide 1 by the decimal odds, so 5/2 implies about 28.6 per cent, evens 50 per cent and 10/1 about 9.1 per cent, before allowing for the bookmaker's margin.

Add up the implied chances of every runner in a race and the total is more than 100 per cent. The excess is the bookmaker's margin, known as the overround, and it means the implied chance of each horse is slightly higher than its fair chance. Knowing the implied chance lets you compare the market's view with your own reading of the form.

How often do horses at each starting price actually win?

Across ten seasons of British and Irish racing, runners starting at 5/1 won 14% of 37,169 runs, close to but below the implied chance of about 16.7 per cent, and 10/1 shots won 7.2%.

The table on this page shows the same comparison for every common price on the Flat, and the ten-season figures draw on 1,201,143 Flat and jumps runs. Horses at most prices win slightly less often than their implied chance, which is the bookmaker's margin at work. The actual versus expected figure

Do horse racing odds change before the race starts?

Yes. Prices move from the first show in the morning to the off as money arrives, non-runners are announced and the market reacts to going changes, so the starting price is often different from the early price.

A horse whose price shortens is a steamer and one whose price lengthens is a drifter. If you take a fixed price, you are paid at that price whatever happens later, unless the bookmaker offers a best odds concession that pays the bigger starting price. Watching the market move across bookmakers is one of the clearest ways to see where money is going.

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