Doubles, trebles and accumulator bets explained

How do accumulator odds multiply leg by leg?

Convert each price to decimal and multiply them together. A treble at 2/1, 3/1 and evens is 3.0 times 4.0 times 2.0, which is 24.0, so £10 returns £240.

Think of it as a chain. The £10 stake goes on the first horse. If it wins at 2/1, the whole £30 return rides on the second horse. If that wins at 3/1, £120 rides on the third. An evens winner doubles it to £240. If any link breaks, the chain ends and the stake is lost, however well the other legs ran.

Decimal odds make the maths easy because they already include the stake. A fractional price converts by dividing and adding one: 5/2 is 3.5, 11/4 is 3.75 and 4/6 is about 1.67.

What are doubles, trebles and fourfolds?

A double links two selections, a treble three and a fourfold four. All are accumulators, or accas, in which the return from each leg rides on the next and every leg must win.

The legs must be in different races, since two horses in one race cannot both win. They can be spread across meetings and days, and the bet stays open until the last leg is run. Multiples such as the Trixie, Yankee and Lucky 15 are simply bundles of these doubles, trebles and fourfolds placed together on one slip.

What happens to an accumulator when one horse is a non-runner?

The non-running leg is made void and the bet continues on the remaining selections. A fourfold with one non-runner becomes a treble, and a double becomes a single.

The stake is not refunded, it simply rides on fewer legs. If a Rule 4 deduction applies to another leg because a runner was withdrawn from its race, that leg's winnings are reduced before the return rolls on to the next leg. Dead heats work the same way: the stake carried into that leg is divided by the number of horses sharing the place, and the reduced amount is paid at full odds.

How does an each way accumulator pay?

An each way accumulator is a win accumulator plus a place accumulator. If any leg only places, the win part loses, while the place part pays when every leg has at least placed.

The place accumulator multiplies each leg's place odds. A leg at 8/1 with one fifth place terms counts at 2.6 in decimal, and a leg at 4/1 at one quarter counts at 2.0. A £5 each way double on those two horses, both placed but neither winning, returns 5 x 2.6 x 2.0, which is £26 against a £10 stake.

Each way terms for each leg follow that race's field size and type, so check them for every leg rather than assuming they match. If one leg wins and another only places, the win accumulator is lost but the winner still counts at its place odds in the place accumulator.

How does the bookmaker margin compound through an accumulator?

Each leg carries its own margin, and multiplying the legs multiplies the margins too. A four leg accumulator carries far more margin than any single bet within it.

Suppose every race is priced with a book adding up to 110 on a scale where 100 is fair. A single carries that 10 point margin. A double multiplies two such books, 1.10 times 1.10, which is 1.21. A fourfold reaches about 1.46 and a sixfold about 1.77. The price on the slip looks generous because the legs multiply, but so does the edge built into them.

Real books vary by race and bookmaker. The live figures on this page show the average overround across the bookmakers RaceWatch tracks over the last 30 days, which is the starting point for any leg.

How can accumulators be kept within a betting budget?

Treat the stake as the full amount at risk, since one losing leg ends the bet. Setting a fixed budget before racing keeps accumulator stakes in proportion.

Accumulators are appealing because a small stake can produce a large return, and most of the time that is not what happens. Keep a record of every multiple placed, including the ones that fail on the last leg, and compare the total staked with the total returned over a few months. That record is the most honest measure of whether the bets fit your budget.

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