This calculator is an educational tool to understand how accumulator maths works. Gambling carries significant financial risk. The house always has a mathematical edge. Only gamble with money you can afford to lose. If gambling is affecting you or someone you know, contact GamCare: 0808 8020 133 or visit BeGambleAware.org. 18+ only.
Enter up to 8 selections with their odds to calculate potential accumulator returns, combined probability of winning, and expected value. Supports decimal, fractional, and American odds formats.
A football accumulator (often called an acca) is a single bet that combines two or more individual selections into one wager. Every selection must win for the bet to pay out. If even one selection loses, the entire accumulator loses.
The appeal of accumulators lies in the compounding of odds — each selection's odds multiply together, meaning a relatively modest set of individual prices can produce a large combined return. A four-team accumulator of four 2/1 shots (3.0 decimal each) would pay 3.0 × 3.0 × 3.0 × 3.0 = 81 times the stake.
Step-by-step example:
| Selection | Fractional Odds | Decimal Odds |
|---|---|---|
| Team A to win | 1/1 (Evens) | 2.00 |
| Team B to win | 1/2 | 1.50 |
| Team C to win | 6/4 | 2.50 |
| Team D to win | 4/5 | 1.80 |
Combined decimal odds = 2.0 × 1.5 × 2.5 × 1.8 = 13.50
With a £10 stake: Total Return = 13.50 × £10 = £135.00 (Profit: £125.00)
| Fractional | Decimal | Implied Probability |
|---|---|---|
| 1/10 | 1.10 | 90.9% |
| 1/4 | 1.25 | 80.0% |
| 1/2 | 1.50 | 66.7% |
| 4/5 | 1.80 | 55.6% |
| Evens (1/1) | 2.00 | 50.0% |
| 6/4 | 2.50 | 40.0% |
| 2/1 | 3.00 | 33.3% |
| 5/1 | 6.00 | 16.7% |
| 10/1 | 11.00 | 9.1% |
Formula: Decimal Odds = (Numerator ÷ Denominator) + 1. So 5/1 = (5 ÷ 1) + 1 = 6.0, and 1/2 = (1 ÷ 2) + 1 = 1.5.
The probability of winning an accumulator is the product of the individual win probabilities. Implied probability from bookmaker odds = 1 ÷ Decimal Odds.
For our 4-selection example (2.00, 1.50, 2.50, 1.80):
However, implied probability from bookmaker odds always overstates the true probability because bookmakers include a margin (overround). Each set of odds has roughly 5–10% margin built in. On a 4-fold, these margins compound, making the true chance of winning even lower than the implied probability suggests.
In a simple single bet, a bookmaker might take a 5% margin. The true odds on a coin flip are 2.00, but they might offer 1.90. In an accumulator, every leg compounds that margin:
| Legs | Single Leg Margin | Approximate Combined Bookmaker Edge |
|---|---|---|
| 1 (single) | 5% | ~5% |
| 2 (double) | 5% per leg | ~10% |
| 4 (four-fold) | 5% per leg | ~19% |
| 6 (six-fold) | 5% per leg | ~26% |
| 8 (eight-fold) | 5% per leg | ~34% |
This means the expected value of an 8-fold accumulator is approximately −34p for every £1 staked — more than six times worse than a single bet. Accumulators are mathematically among the worst-value bets available.
4 singles + 6 doubles + 4 trebles + 1 four-fold = 15 bets. At least one winner returns. Cost: 15 × unit stake.
6 doubles + 4 trebles + 1 four-fold = 11 bets. Need 2+ winners. No singles. Cost: 11 × unit stake.
5 singles + 10 doubles + 10 trebles + 5 four-folds + 1 five-fold = 31 bets. Cost: 31 × unit stake.
21 doubles + 35 trebles + 35 four-folds + 21 five-folds + 7 six-folds + 1 seven-fold = 120 bets. Cost: 120 × unit stake.
Expected Value (EV) is the mathematically correct measure of whether a bet is profitable in the long run. The formula is:
For an accumulator with a 7.41% implied win chance, returning £125 profit on a £10 stake:
EV = (0.0741 × £125) − (0.9259 × £10) = £9.26 − £9.26 = £0.00 (theoretical breakeven at exact fair odds)
In practice, because bookmakers build in a margin, the actual EV is negative. Accumulators should be understood as entertainment, not an investment strategy.
You can also set deposit limits, loss limits, and session time limits directly with any UKGC-licensed bookmaker. These tools are free and can be activated immediately in your account settings.
A football accumulator (acca) is a single bet that combines multiple individual selections into one wager. All selections must win for the bet to pay out. Returns are calculated by multiplying all the decimal odds together, then multiplying by the stake. The more selections, the higher the potential return — but the lower the probability of winning.
Multiply all decimal odds together, then multiply the result by your stake. Example: 4 selections at 2.0, 1.5, 2.5, 1.8. Combined odds = 2.0 × 1.5 × 2.5 × 1.8 = 13.5. With a £10 stake: returns = 13.5 × £10 = £135 (profit £125). To convert fractional odds to decimal: Decimal = (numerator ÷ denominator) + 1. So 5/1 = 6.0, evens = 2.0, 1/2 = 1.5.
If each of 4 selections is at even money (2.0 decimal, 50% implied probability), the 4-fold has a win probability of 0.5 × 0.5 × 0.5 × 0.5 = 6.25%. With bookmaker margin factored in, the true probability is even lower. Longer accumulators have very small win probabilities — a 10-fold of 50% selections would win only 0.098% of the time (roughly 1 in 1,024).
A Lucky 15 is a full coverage bet on 4 selections comprising 15 separate bets: 4 singles, 6 doubles, 4 trebles, and 1 four-fold accumulator. At least one selection must win to get a return. Unlike a simple 4-fold where you need all 4 to win, the Lucky 15 provides returns even if only one or two selections win, but it costs 15 times your unit stake.
A Yankee is a bet on 4 selections comprising 11 bets: 6 doubles, 4 trebles, and 1 four-fold accumulator. There are no singles, so at least 2 selections must win to get a return. It costs 11 times your unit stake. A Yankee provides partial coverage compared to a simple 4-fold accumulator, at less cost than a Lucky 15.
Bookmakers build a margin (overround) into every set of odds — typically 5–10% per event. In an accumulator, this margin is applied to every leg and compounds across the bet. A 5% margin per leg in a 5-fold accumulator results in approximately 23% total edge for the bookmaker, compared to just 5% on a single. Accumulators are mathematically far worse value for the bettor despite their appeal.
UK support services include: GamCare (gamcare.org.uk, helpline 0808 8020 133), BeGambleAware (begambleaware.org), Gamblers Anonymous (gamblersanonymous.org.uk), and GamStop (gamstop.co.uk) for self-exclusion from all UKGC-licensed online gambling. The National Gambling Helpline is free and available 24/7 on 0808 8020 133. Gambling should always be treated as entertainment, with strictly defined budgets.