Accumulator betting explained

An accumulator (often shortened to "acca") combines two or more separate selections into a single bet, where the winnings from each selection roll onto the stake for the next one. Every selection has to win for the bet to pay out at all — a single losing leg loses the whole bet, however well the other legs did.

Key facts

• All selections must win — there's no partial credit. Unlike an each-way bet's separate win/place parts, an accumulator either pays out in full or not at all, based on every leg.
• Odds compound multiplicatively, not additively. Combining several moderate-odds selections can produce a large headline price, because each leg's odds multiply the running total rather than simply adding to it.
• A two-selection accumulator is specifically called a "double." Longer accumulators (treble, four-fold, and so on) follow the same winnings-roll-forward principle with more legs.
• A voided or postponed leg is normally just removed from the bet, with the remaining legs settled as if that selection had never been included — see our void bets guide for when this applies.

Worked example

You place a £10 four-selection accumulator at decimal odds of 2.0, 1.5, 3.0 and 2.5. If all four win, the payout is calculated by multiplying the odds together (2.0 x 1.5 x 3.0 x 2.5 = 22.5) and applying that to your stake: £10 x 22.5 = £225 total return, including your original stake. If any one of the four selections loses, the whole bet loses — there's no partial return for the three legs that won.

How dead heats and Rule 4 interact with an accumulator

If one selection in an accumulator dead-heats rather than winning outright, that leg's stake is halved and full odds applied to the reduced amount — the resulting figure then becomes the stake carried into the next selection, per Tattersalls Committee's own Rules on Betting. If a horse-racing leg is affected by a Rule 4 non-runner deduction, that reduction is applied to the winnings from that leg specifically, in the same way it would be on a single bet — see our dead heat and Rule 4 guides for the mechanics of each on their own.

Why accumulators appeal — and why the risk is real

The multiplicative effect is exactly what makes accumulators attractive: a handful of modest, individually plausible selections can combine into a large potential return from a small stake. It's also exactly why they're higher-risk than single bets — the probability of every leg winning is the product of each individual leg's probability, which falls quickly as legs are added, even when each individual selection looks like reasonable value on its own.

Common misconceptions

• "A good accumulator just needs mostly-winning legs." There's no partial win — every single leg has to come in for the bet to pay out at all.
• "Bigger accumulators are proportionally more likely to include a winner." Adding legs increases the potential payout, but it reduces the overall probability of the whole bet winning, since every additional leg is another chance to lose the entire bet.
• "Cash out isn't available on accumulators." Many bookmakers do offer full or partial cash out on multi-selection bets, though availability is commonly more limited than on single bets — see our cash out guide for how that's priced.

Related content

See our guides to betting odds explained for the underlying odds mechanics, each-way betting for a different multi-part bet structure, and cash out explained for settling an accumulator early.