What this guide covers
An accumulator, called an acca in the UK and a parlay in the US, is one bet made of several picks from different events. This guide shows the math behind it, explains what happens when a leg is voided or ends in a dead heat, and compares it with singles. For picks from one match, see bet builder instead.
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How it works
You add picks from different matches to your slip and choose the accumulator option. The slip multiplies the odds of each leg to give one combined price. Every leg must win for the bet to pay. If one loses, the whole bet loses.
A double has two legs, a treble three, and anything bigger is usually just called a four-fold, five-fold and so on. Some books also offer system bets, which bundle several smaller multiples together so one loser doesn't sink everything. Those cost more, because they're several bets in one.
The math
Three picks at 2.00 multiply to 8.00. That looks generous until you see the chance: if each is actually 50%, all three win only 12.5% of the time. Add the bookmaker's margin on every leg and the cost grows.
Legs and chance
| Legs at 50% each | Chance all win |
|---|---|
| 2 | 25% |
| 3 | 12.5% |
| 5 | About 3% |
The table uses fair coin-flips. Real prices include a margin. If each leg is priced at 1.91 instead of 2.00, a single leg gives back about 95.5% of its fair value. Three legs give back 95.5% times 95.5% times 95.5%, about 87%. Five legs, about 79%. The more legs, the bigger the share the book keeps. That's why accumulators usually cost more than singles, even though the headline price looks better.
Why people still like them
Accumulators turn a small stake into a large possible return, and they make a weekend of games feel connected. That's the appeal, and it's fine as long as you see them for what they are: a long shot with a bigger margin. A sensible way to treat an acca is as a small, fun bet, not as your main way of betting.
Voids and dead heats
A postponed match often becomes a void leg, and the accumulator continues with fewer legs.
When a leg is voided, it's usually treated as if it had odds of 1.00. Your four-fold becomes a treble at a lower price. The bet usually doesn't lose because of the void. If a match is postponed and replayed within the time Stake's rules allow, the leg may stand instead.
Dead heats happen when two selections tie, for example two players finishing level as top scorer. Under dead-heat rules, the stake on that leg is split, which reduces the price used for that leg. Your acca can still win, but it pays less than you expected. Stake's sports rules set how voids and dead heats are handled.
What happens when a leg changes
| Leg outcome | Usual effect on the accumulator |
|---|---|
| Wins | The acca continues |
| Loses | The whole acca loses |
| Void | Leg usually drops out, price falls |
| Dead heat | Leg usually pays at a reduced price |
Accumulators and cash out
With one or two legs left, cash-out offers on an acca can look large next to the stake. The offer is based on the live value of your remaining legs, minus a margin. Whether to take it is a question of how much risk you want, not a hidden trick. Our cash out guide explains the sum.
Boosts and promotions
Sportsbooks sometimes run accumulator boosts that add a percentage to winning accas. If Stake offers one, the rules on minimum legs, minimum odds and eligible markets will be in the promotion's terms. Read them on Stake, and our bonus page explains how to judge a promotion. A boost lowers the margin a little. It doesn't change the leg math.
A worked example
Made-up weekend: four football picks at 1.70, 1.90, 2.10 and 1.55. Multiplied, that's about 10.51, so a 5 stake returns about 52.57 if all four win. Now say the third match is postponed and the leg is voided. The bet becomes a treble at 1.70 times 1.90 times 1.55, about 5.01. If the other three win, you get about 25.03 back. Had the first leg lost, nothing else would have mattered.
Related
See bet builder, odds explained and cash out.
Singles versus one accumulator
Say you like four picks. You could place four singles of 5 each, or one four-fold of 20. The singles can each win or lose on their own, so a single bad result costs you 5. The four-fold needs all four, and one bad result costs you all 20. Over many weekends, the singles also pay less margin. The four-fold has the bigger headline return and a much lower chance of paying at all. Neither is wrong, but they're different bets, and the accumulator is the riskier one.
Keeping it in proportion
A big acca price is easy to dream about and rarely lands. Keep accumulator stakes small and occasional. Treat every bet as money you can lose, and if you're chasing losses, stop and read our responsible gambling page.
FAQ
Are accumulators good value?
They combine margins, so they're usually worse value than singles.
Is there an accumulator boost?
Check current promotions.
Can I cash out an accumulator?
Often.
What happens if one match in my acca is postponed?
That leg is usually voided and the rest stand at a lower price, unless the match is played within the time Stake's rules allow.