An accumulator is one bet on several selections. Every one has to win. The odds multiply, which is why accas pay so well and why they lose so often.
How the odds multiply
Multiply the decimal odds of each leg together. Five selections at evens (2.0) gives 2 × 2 × 2 × 2 × 2 = 32.0, or 31/1. So £1 returns £32.
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Your real chance of winning
The chances multiply too. If each of those five legs is a genuine 50% shot, the chance of all five winning is 0.5 × 0.5 × 0.5 × 0.5 × 0.5. That's about 3.1%, or roughly one acca in 32.
| Legs | Chance all win |
|---|---|
| 2 | 25% |
| 3 | 12.5% |
| 4 | 6.3% |
| 5 | 3.1% |
| 8 | 0.4% |
| 10 | 0.1% |
Why the bookmaker loves accas
Every price has a margin built in. In an acca the margins multiply along with the odds. If each leg is priced at 95% of its fair value, a five leg acca pays about 77% of what it should. That's a much bigger cut than on a single bet.
Accas are fine as a fun, small stake bet. But the maths works against you more than it does on a single.
Check your acca returns with the acca calculator.Acca calculator →Questions people ask
What is an accumulator?
An accumulator, or acca, is a single bet that links four or more selections. Every selection has to win for the bet to pay. Two selections is a double and three is a treble.
What happens if a leg is postponed?
It's usually made void and the acca carries on with one fewer leg. Check your bookmaker's rules on how long they wait.
What is acca insurance?
A promotion where the bookmaker refunds your stake, often as a free bet, if one leg lets you down. Terms vary, so read them before you rely on it.