How to Calculate Returns on a Horse Racing Accumulator

What it means

For an accumulator, multiply all decimal odds together and then multiply by the stake.

An accumulator multiplies the decimal prices of winning legs; every live leg must succeed for the standard accumulator to win.

A worked example

A £5 double at decimal 2.0 and 3.0 returns £5 × 2 × 3 = £30 if both win.

Three winners at decimal 2.0, 3.0 and 4.0 give combined odds 24.0. A £5 stake returns £120 including stake.

How to check the numbers

Convert every quote into decimal odds and an implied probability before comparing prices. Use the price available when the bet could actually be placed, not a later historical quote.

Common mistakes and limitations

If any leg loses, the entire accumulator loses unless special rules apply.

A mathematical edge depends on the quality of the probability estimate; small errors in estimated chance can reverse an apparent advantage.

Three-leg accumulator example

Suppose three selections have decimal odds 2.0, 2.5 and 3.0. The combined price is 2 × 2.5 × 3 = 15.0 decimal, equivalent to 14/1. A £10 accumulator returns £150 including stake if all three win, and normally loses the £10 if any leg loses.

Practical checks and limitations

If a selection is a non-runner, the treatment of that leg depends on the market and operator rules. A higher combined price also means all required outcomes must occur.