Accumulator calculator

Worked example

What does a 10 4-fold at 1.80, 2.10, 1.50, 1.95 pay, and how likely is it?

The prices say all four land about 9% of the time, and with each leg's margin compounded the true chance is lower still.

The arithmetic

An accumulator pays the product of its legs: the return from the first selection is staked in full on the second, and so on. Converting each leg to a decimal price and multiplying gives the combined price, and the stake times that price is the return. Void legs (a postponed match, a non-runner) are settled at 1.00 and drop out of the multiplication.

Why the price looks big

The combined price is large because the combined chance is small, and the two are not quite inverses: the bookmaker’s margin is in every leg, so the implied probability of the accumulator overstates the true one by the compounded margin. At a 5% margin per leg the book keeps around 10% of a double, 16% of a treble and 22% of a four-fold — before any question of whether the selections are good ones.

That is why value bettors stake singles. A selection with a genuine edge keeps that edge as a single; put it in an accumulator with three selections that have none, and the whole bet is negative expectation.

Questions

How are accumulator odds calculated?

Multiply the decimal price of every leg. Four legs at 1.80, 2.10, 1.50 and 1.95 give 1.8 × 2.1 × 1.5 × 1.95 = 11.06, so a 10 stake returns 110.57.

What is the chance of an accumulator winning?

The product of the chances of every leg. Four selections that each land 60% of the time land together 0.6⁴ = 13% of the time. The calculator shows the chance the prices imply, which includes the margin and is therefore higher than the true chance.

Why are accumulators poor value?

Because every leg carries the bookmaker’s margin and the margins multiply. Four legs at a 5% margin each give the book a 21.6% edge on the whole bet, against about 5% on a single. The bigger the accumulator, the larger the share of the return that is margin.

What are a double, a treble and a four-fold?

Names for the number of legs: a double has two selections, a treble three, and from four upwards the bet is a four-fold, five-fold and so on. The arithmetic is the same at every size — multiply the decimal prices — and this calculator takes up to ten legs.

Can I work out an each-way accumulator?

Yes: choose “Each way” and the place terms. Half the stake goes on the win part at the win prices and half on the place part at each leg’s place fraction (a quarter of 6/4 is 6/16, so 1.375 in decimal). If every selection wins, both parts pay; if every selection places but not all win, only the place part does.

What happens if one leg is void?

A postponed match or a non-runner settles at 1.00 and drops out of the multiplication: a four-fold with one void leg pays as a treble on the other three. Leave that leg out, or enter 1.00, to see the adjusted return.

Does this site advise accumulators?

No. Every selection is published as a single and settled as a single. Combining selections multiplies the margin and the model error alike.

The same numbers on real fixtures

• This week’s advised singles
• The margin on each leg
• Whether one leg is worth backing on its own

The model’s probability for every fixture, by market: over 2.5 goals · under 2.5 goals · both teams to score · home wins · all of tomorrow’s matches.

The model does this arithmetic on every price it captures. Members see every pick it publishes, with the price, the stake and the reasoning, from the moment it is published. See what members get →