Singles, Doubles, Trebles & Accumulators
From a straightforward single bet to a multi-leg accumulator that turns a small stake into a large potential return — this guide covers every type of multiple bet, how each one works, how returns are calculated, and when each makes sense to use.
Singles
A single is one bet on one outcome. If it wins, you collect. If it loses, the bet is over. It's the most straightforward bet type in existence — and the one that offers the clearest measure of your betting performance over time.
A single bet has one selection and one result. You stake a fixed amount, the event takes place, and either you win or you lose. There are no moving parts — the return is simply your stake multiplied by the odds.
Single — Example
Selection: Arsenal to Win
Odds: 2.40
Stake: £20
Return if wins: £20 × 2.40 = £48
Profit if wins: £28
Why Singles Make Sense
Singles give you a clean measure of your edge. Every bet stands on its own merits. There's no compound risk — one selection going wrong doesn't wipe out the entire bet. For serious bettors, singles are the standard.
Singles are the building block of all other bet types. Every leg of a double, treble or accumulator is effectively a single — the difference is in how the returns from each leg are treated.
Doubles
A double combines two selections into a single bet. Both selections must win for the bet to pay out. The return from the first selection rolls automatically onto the second — you don't receive the winnings in between, they compound.
Total return = Stake × Odds₁ × Odds₂
The combined odds are simply the two decimal odds multiplied together.
Double — Worked Example
Leg 1: Man City Win
Odds: 1.80
Leg 2: Liverpool Win
Odds: 2.10
1.80 × 2.10 = 3.78
This is the effective odds of the double.
£10 × 3.78 = £37.80
✅ Profit: £27.80 if both winThe entire bet loses. Winning Leg 1 only does not return anything — both must win for any payout.
❌ One loss = full stake lostCompared to placing two separate singles of £5 each, a £10 double produces a much higher return if both win — but loses everything if either fails. The double is a higher-risk, higher-reward version of two singles.
Trebles
A treble works exactly like a double but with three selections. All three must win. The winnings from the first roll into the second, and the winnings from the second roll into the third — compounding with each leg.
Total return = Stake × Odds₁ × Odds₂ × Odds₃
Treble — Worked Example
Leg 1: Chelsea Win
Odds: 2.00
Leg 2: Bayern Win
Odds: 1.75
Leg 3: PSG Win
Odds: 2.20
2.00 × 1.75 × 2.20 = 7.70
£10 × 7.70 = £77.00
✅ Profit: £67.00 if all three winThe whole bet loses, regardless of which leg it was. All three selections must win.
❌ One loss = full stake lostNotice how the combined odds of 7.70 are significantly higher than any individual selection. This is the power of compounding — and also the danger. Add a fourth leg and the odds grow further, but the probability of all four winning drops sharply.
Accumulators — 4-Fold and Beyond
An accumulator (or acca) is any multiple bet with four or more selections. The naming convention is simple: four selections is a 4-fold, five is a 5-fold, and so on up to whatever the bookmaker allows — typically 20 legs or more.
Double
2 selections
Both must win
Treble
3 selections
All must win
4-Fold Acca
4 selections
All must win
5-Fold Acca
5 selections
All must win
6 to 10-Fold
6–10 selections
All must win
11-Fold and Beyond
11+ selections
All must win
4-Fold Accumulator — Worked Example
Leg 1: Real Madrid Win — 1.60
Leg 2: Juventus Win — 2.00
Leg 3: Celtic Win — 1.90
Leg 4: Ajax Win — 2.30
1.60 × 2.00 × 1.90 × 2.30 = 13.98
£10 × 13.98 = £139.80
✅ Profit: £129.80 if all four win
Each leg's implied probability:
1÷1.60 = 62.5%, 1÷2.00 = 50%, 1÷1.90 = 52.6%, 1÷2.30 = 43.5%
Combined: 0.625 × 0.50 × 0.526 × 0.435 = 7.2% chance
Use our free Accumulator Calculator to calculate the combined odds, potential return and win probability for any acca instantly.
How Accumulator Returns Are Calculated
The mechanics of how an accumulator pays out are worth understanding clearly — particularly what happens when one leg is a void or a non-runner.
Total return = Stake × (Odds₁ × Odds₂ × Odds₃ × ...)
Each leg's decimal odds are multiplied together to get the combined
odds. Multiply by stake for the total return. Subtract stake for profit.
What Happens if a Leg is Void?
If one leg of your accumulator is voided — for example a horse race is abandoned, or a match is postponed — that leg is removed from the bet and the accumulator continues with the remaining legs. The void leg effectively becomes odds of 1.00 (no effect on the calculation).
Becomes a Treble
A 4-fold accumulator with one void leg automatically becomes a treble. The remaining three selections must all win. Your return is calculated on the three remaining sets of odds only.
Becomes a Single
A double with one void leg becomes a single on the remaining selection. If it wins you receive your return based on those odds alone. The full stake is still active on the remaining leg.
What Happens if a Leg is Pushed / Drawn?
In some bet types — particularly in American sports where draws are common — a push (a draw result in a spread or total bet) is treated like a void, with that leg removed and the acca continuing. In standard football or racing accas, a draw on a "to win" selection is a losing bet — the leg loses and the whole acca loses with it.
The Catch — Why Accumulators Are Hard to Win
The appeal of an accumulator is obvious: a small stake, a large potential return. But the odds are stacked against you in a way that's easy to underestimate.
Every leg you add to an accumulator doesn't just multiply the payout — it also multiplies the bookmaker's margin. A 5% margin per leg becomes roughly a 25% combined margin across a 5-fold. This is why accumulators are the most profitable product bookmakers offer.
To illustrate how dramatically win probability drops as legs are added, consider five selections each at evens (2.00 — a 50% chance each):
Double (2 legs)
Win probability:
50% × 50% = 25.0%
Combined odds: 4.00
Treble (3 legs)
Win probability:
50% × 50% × 50% = 12.5%
Combined odds: 8.00
4-Fold (4 legs)
Win probability:
50%⁴ = 6.25%
Combined odds: 16.00
5-Fold (5 legs)
Win probability:
50%⁵ = 3.125%
Combined odds: 32.00
A five-leg acca of evens shots has just a 3.125% chance of winning — less than 1 in 30. And because the bookmaker has built their margin into every leg, the true odds are even longer than the advertised combined price suggests. Accumulators are fun — but they are, statistically speaking, a significant negative-expectation bet for the bettor.
Singles vs Multiples — When to Use Each
The choice between singles and multiples isn't purely mathematical — it also depends on your goals, bankroll and approach to betting.
You Want to Measure Your Edge
Singles give you the clearest picture of whether you have a genuine betting edge. Each bet is evaluated independently. Your ROI over time tells you exactly how well you're performing. Serious and professional bettors overwhelmingly use singles.
You Want Big Returns From a Small Stake
If you have strong conviction across several selections and want to maximise the potential return from a small outlay, multiples make sense. They're also appropriate for casual, recreational betting where the entertainment value of a big potential win is part of the appeal.
Every multiple compounds the bookmaker's margin. A value bettor who finds edges on individual selections will realise that edge more efficiently through singles than through accumulators, where each additional leg dilutes the overall expected value.
✅ More legs = more margin against youIf your bankroll is limited and you're looking for a life-changing return from a small bet, an accumulator is the vehicle. A £5 acca at combined odds of 500.00 pays £2,500 — the kind of return that would take years to generate through singles on the same stake. The trade-off is a very low win probability.
📊 Higher variance, higher potential rewardIn horse racing, each way accumulators give you two parallel bets — one on all selections to win, one on all to place. If several selections place but don't win, the place acca can still return a significant profit. See our guide on Each Way Betting Explained for how this works.
Acca Insurance and Bonuses
Most major bookmakers offer some form of acca promotion — typically insurance on a losing leg or an odds boost. Understanding what these actually offer helps you decide whether they represent genuine value.
Acca Insurance
If one leg of your accumulator loses, the bookmaker refunds your stake as a free bet (up to a maximum amount). Usually requires a minimum number of legs (typically 5+) and minimum odds per leg. The refund is a free bet token, not cash — which affects the true value.
Acca Boost
The bookmaker increases your payout by a percentage based on the number of legs — e.g. 5% extra for a 5-fold, 10% for a 6-fold. These boosts are applied to the profit, not the total return. They partially offset the bookmaker's margin on multiples.
Free Bet Accas
Some promotions award a free bet for use on an accumulator. Free bets on accas can be highly valuable because the compounded odds amplify the stake equivalent of the free bet significantly. A £5 free bet on a 10.00 acca returns £50 in profit — the free bet "value" is magnified by the odds.
Read the Terms
Acca bonuses almost always come with minimum odds per leg, minimum number of legs, and payout caps. The refund on acca insurance is typically a free bet with wagering attached — not withdrawable cash. Always read the full terms before relying on these promotions.
Common Questions
Nothing — they're the same thing with different names. Accumulator is the standard British term; parlay is the American equivalent. Both describe a single bet that combines multiple selections where all must win and winnings roll over from leg to leg. You may also hear the term "multi" used in Australia. The mechanics are identical regardless of what it's called.
Yes — you can use the same selection in as many separate accumulators as you like, as long as they're independent bets. What you generally can't do is include the same selection twice within a single accumulator — bookmakers prohibit "correlated" selections (where the result of one directly affects the result of another) and will void or reject bets that contain the same event twice.
Yes — every bookmaker has maximum payout limits that apply to all bets including accumulators. These limits vary significantly: some bookmakers cap football acca payouts at £500,000, others at £1,000,000. For very long-odds accumulators on smaller markets, the limit may be much lower. The maximum payout is always listed in the bookmaker's terms and conditions — worth checking before placing a high-stake acca.
From a pure expected value perspective, multiple singles on the same selections almost always offer better value than a single accumulator — because each additional leg in an acca adds another layer of the bookmaker's margin. However, if your goal is a large return from a small stake, the acca is the only practical vehicle. The question is really about your objectives: consistent long-term returns (singles) vs high-variance, high-reward entertainment (accumulators).
It varies by bookmaker and sport. Most major UK bookmakers allow accumulators of up to 20 legs on football. Some allow more for horse racing or other sports. In practice, the combined odds on a 20-fold acca can reach into the millions — at which point the bookmaker's maximum payout cap becomes the binding constraint rather than the number of legs. Always check the individual bookmaker's rules for the sport you're betting on.
Ready to calculate your accumulator? Our free Accumulator Calculator shows your combined odds, potential return and win probability for any number of selections — in decimal, fractional or American odds.
Try the Accumulator Calculator →