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Last checked 21 October 2026 by Tom Perkins. Calculations checked by us against the rules cited below.
An accumulator (acca) is one bet on several selections in which every leg must win. The return from each leg rolls onto the next, so the odds multiply. A double has two legs and a treble three; four or more is usually called a four-fold, five-fold and so on.
How the odds multiply
Multiply the decimal odds of each leg, then by the stake. A £10 double on a 2/1 winner (3.0) and a 7/1 winner (8.0) returns £10 × 3 × 8 = £240.
Worked example (illustration only)
£5 treble on 2/1 (3.0), evens (2.0) and 6/4 (2.5): 3 × 2 × 2.5 = 15, so it returns £75. If any leg loses, the whole bet loses.
What happens if a leg is void
A void leg (a non-runner, a postponed match not played within the bookmaker’s time limit, or a void market) is normally removed and the bet is settled on the remaining legs. In the treble above, if the evens leg is void, it becomes a double: 3 × 2.5 = 7.5, returning £37.50. Bookmakers set their own void and postponement rules, so check them.
Dead heats in a double
Under Tattersalls Rule 10(a), if one selection in a double dead heats, the stake on it is halved at full odds and that becomes the stake on the next selection. £10 double on 2/1 and 3/1, where the first dead heats for a two-way tie: £5 × 3 = £15 runs on at 3/1, so it returns £60. See dead heat rules.
System bets
A system bet covers some or all combinations of your selections at a given size. “2 from 4” is all 6 doubles from 4 selections; “3 from 5” is all 10 trebles from 5. Full-cover bets such as the Yankee and Heinz are named systems. See the full-cover bets hub and use the bet calculator there.
Each-way accas
An each-way acca is two accas: one at win odds and one at place odds. The place acca can pay if every leg at least places, even if the win acca loses.
Acca offers
Acca insurance and acca boosts are bookmaker promotions with minimum legs, minimum odds and maximum refunds that vary by operator. Our acca insurance guide explains what to check. A bet builder is different: it combines markets from the same match.
Can you use a free bet on an accumulator?
Sometimes. It depends on the token: some welcome offers include free bets that can only be used on accas, while others limit them to singles. Examples we checked on the bookmakers’ own pages on 21 October 2026:
- Midnite (code BETGET30): part of the £30 in free bets is a £5 pre-match acca free bet for 4+ selections at odds of 4/1 or more.
- Stakemate: each of the 4 × £5 free bets needs 3+ selections at total odds of 3.0 or more.
- Sky Bet: the 3 × £10 welcome free bets can be used on singles and each-way bets, not accas.
18+. New customers only. These are the significant terms as published by each bookmaker on 21 October 2026; the full terms are on the bookmaker’s site and can change, so read them before you opt in. BeGambleAware.org
A free bet stake isn’t returned with winnings, and an acca token’s minimum number of legs makes it less likely to win than a single. Our guide to how free bets work shows what a token is really worth.
Why accas are hard to win
The probabilities multiply as well as the odds. Four selections that each have a 50% chance, all winning, is 0.5⁴ = 6.25%. Each leg also carries the bookmaker’s margin, so the margin compounds. Read implied probability explained for more.
Current sports offers
The offers below are for new customers aged 18+ at UKGC-licensed bookmakers. Each one has its own terms, minimum odds and expiry, so read them before you opt in. Our free bets page explains how tokens work.
New customers. Min £5 deposit. First bet only: min 5p single/each-way at odds 1/1+ within 30 days of registration. 3 x £10 Free Bets (singles/each-way, excl. virtuals), expire after 30 days. Free Bet stakes not returned. Neteller and Skrill deposits excluded. No wagering on Free Bet winnings stated.
Promo code:
AB5G30· Low qualifying stake (5p) and Free Bets usable on singles and each-way.Full T&Cs
New Sky Betting and Gaming customers 18+ only (previous Sky Bet, Vegas, Casino, Bingo or Poker account holders excluded). Register, add card details and make a minimum £5 deposit. Your first bet must be a single or each-way bet of at least £0.05 on any Sky Bet market at odds of 1/1 or greater; accumulated smaller stakes do not count and only your first bet counts. Staking requirement must be met within 30 days of registration. Rewards: three £10 Free Bet tokens, usable on any single or each-way market excluding virtuals, not with any other offer. Free Bets expire 30 days after crediting, are non-withdrawable and stakes are not included in returns. One claim per customer. Customers depositing with Neteller or Skrill do not qualify. Offer may differ if you arrive via another link. Sky Bet General Promotion Terms apply.
New customers. Opt in at sign-up. Deposit £10+ and place a £10+ bet at odds 1/1+ within 7 days (excl. virtuals, esports, non-UK/IE racing). 4 x £10 Free Bets: 2 for football accas (4+ legs), 2 for sports multiples (2+ legs), valid 7 days. Free Bet stake not returned.
Rewards credited on settlement of one £10 qualifying bet, win or lose.
Full T&Cs
New BetMGM customers 18+. Select the Sports Welcome Offer at sign-up. Deposit at least £10 and place at least £10 on a qualifying bet within 7 days of registration: min odds Evens 1/1 (2.0); each-way bets need £10 each way (£20 total); Bet Builder total odds must be 1/1+. Excludes virtual sports, esports and non-UK/IE horse racing. Free Bets, Profit Boosts, Odds Boosts, void, cashed-out, partially cashed-out and system bets do not qualify. Not with other offers. On settlement you get 4 x £10 Free Bets: 2 x £10 on football accas (4+ selections) and 2 x £10 on sports multiples (2+ selections), selected via the betslip checkbox. Free Bets expire after 7 days; stake not included in winnings. Once per household/computer/IP. Operated by LeoVegas Gaming plc (UKGC 39198). General and promotional T&Cs apply.
New customers. Opt in at sign-up. Deposit £10+ and place a £10+ bet at odds 1/1+ within 7 days (excl. virtuals, esports, non-UK/IE racing). 4 x £10 Free Bets: 2 for football accas (4+ legs), 2 for sports multiples (2+ legs), valid 7 days. Free Bet stake not returned.
Same LeoVegas offer structure as BetMGM, with UK/IE racing allowed for the qualifier.
Full T&Cs
New BetUK.com customers 18+. Opt in by selecting the Sports Welcome Offer at sign-up. Deposit at least £10 and place at least £10 on a qualifying bet within 7 days of registration: min odds Evens 1/1 (2.0); each-way needs £10 each way; Bet Builder total odds 1/1+. Excludes virtual sports, esports and non-UK/IE horse racing. Free Bets, Profit/Odds Boosts, void, cashed-out, partially cashed-out and system bets do not qualify. Once only; not with other offers. On settlement: 2 x £10 Free Bets on football accas (4+ selections) and 2 x £10 on sports multiples (2+ selections). Unused Free Bets expire after 7 days; stake not included in winnings. Operated by LeoVegas Gaming plc (UKGC 39198). General Promotional and General T&Cs apply.
Frequently asked questions
How many selections can an acca have? It depends on the bookmaker; limits vary.
What is the difference between a double and an acca? A double is a 2-leg acca. “Acca” usually means four or more legs.
Can I cash out an acca? Some bookmakers offer cash out on some accas. It is optional, its value is set by the bookmaker, and it may be unavailable.
What happens if a match in my acca is postponed? If it isn’t played within the bookmaker’s stated time, that leg is usually void and the acca runs on the rest.
What is a system bet? A set of multiples covering combinations of your selections, such as all doubles from four selections.
Can I use a free bet on an acca? Only if the token allows it. Some welcome offers include acca free bets with a minimum number of legs and minimum odds, while others, such as Sky Bet’s, are for singles and each-way bets only.
We post new guides and checked offers on Telegram (18+ only):
Staying in control
Set a deposit limit before your first deposit, decide your budget in advance and never chase losses. Calculators show what a bet could return; they do not make any outcome more likely. You can self-exclude from all online gambling sites licensed in Great Britain for free with GamStop, and many banks let you block gambling payments. The National Gambling Helpline (0808 8020 133) is free, confidential and open 24 hours a day. See our responsible gambling page.
Sources checked
- Tattersalls Committee Rules on Betting (Rule 10a)
- Leicester Racecourse – Betting Terms (double example)
Affiliate disclosure: onlinebetfree.co.uk may receive a commission if you open an account through links on this page. This does not affect the offers we list or how we describe them, and it never changes the terms an operator gives you.
18+ only. Please gamble responsibly. For free, confidential support visit BeGambleAware.org or call the National Gambling Helpline on 0808 8020 133.