Enter each leg's odds and your stake to see the total odds, payout, profit and the chance every leg wins. Free, no sign-up.
OddsFantasy's accumulator builder combines value bets, prices above Pinnacle's no-vig odds, into accumulators (parlays) of 2 to 7 legs at one bookmaker, and shows each slip's total odds and combined expected value. The free calculator above works out the total odds, payout and win chance of any accumulator.
An accumulator is a single bet that combines two or more selections, called legs. Every leg must win for the bet to pay, and the odds of the legs multiply, so the payout grows quickly with each leg you add.
The same bet has different names: an accumulator or acca in the UK, a parlay in the US, a multi in Australia and a combo bet in much of Europe and Africa. A bet builder, or same game parlay, is a different product: it combines selections from one match.
Convert each leg to decimal odds and multiply them. The calculator above applies these formulas:
Total odds = odds of leg 1 × odds of leg 2 × … × odds of leg n
Payout = stake × total odds
Profit = payout − stake
Chance all legs win (implied) = 1 ÷ total oddsAmerican odds convert to decimal first: +150 is 2.50 and −110 is 1.909. Three −110 legs give 1.909 × 1.909 × 1.909 = 6.958, a +596 parlay.
Take three legs at 1.80, 1.95 and 2.10 with a $10 stake:
| Leg | Decimal odds | Running total odds |
|---|---|---|
| Leg 1 | 1.80 | 1.80 |
| Leg 2 | 1.95 | 3.51 |
| Leg 3 | 2.10 | 7.371 |
The total odds are 7.371 (+637). A $10 stake pays $73.71, a profit of $63.71, and the odds imply all three legs win 13.57% of the time.
Because the bookmaker's margin compounds with every leg. A −110 price on a fair 50% outcome carries −4.55% expected value (EV). Five such legs in one accumulator carry −20.8% EV.
| Legs | EV of each leg | EV of the accumulator |
|---|---|---|
| 1 | −4.55% | −4.55% |
| 2 | −4.55% | −8.9% |
| 3 | −4.55% | −13.0% |
| 4 | −4.55% | −17.0% |
| 5 | −4.55% | −20.8% |
The same rule works in your favour when every leg has positive EV, which is how the accumulator builder picks its legs.
The builder starts from OddsFantasy's live value bets: pre-match prices at bookmakers and Polymarket that beat Pinnacle's no-vig odds. You choose:
Each slip takes one leg per match and shows its combined EV, total odds and every leg's event, market, selection, odds and a link to the bookmaker. You can add a slip to the bet tracker. The builder is included in the Classic plan; the calculator on this page is free.
For independent legs, the EV of an accumulator is the product of one plus each leg's EV, minus one. The builder uses this formula:
Accumulator EV = (1 + EV of leg 1) × (1 + EV of leg 2) × … × (1 + EV of leg n) − 1Three legs at +2% EV give 1.02 × 1.02 × 1.02 − 1 = +6.12% EV, and seven give +14.87%. Legs from the same match are not independent, so the builder never combines them.
A value accumulator compounds the edge and the variance. Three legs at 1.80 with +2% EV each make a +6.12% EV accumulator that wins about 18.2% of the time, against about 56.7% for each single. Stake accumulators smaller than singles to ride out the longer losing runs; the Kelly calculator shows how edge and odds set a stake.
Convert every leg to decimal odds and multiply them. Three legs at 1.80, 1.95 and 2.10 give total odds of 7.371, so a $10 parlay pays $73.71. The calculator on this page does it for decimal and American odds.
An acca builder puts accumulator bets together for you. OddsFantasy's accumulator builder only uses value bets, prices above Pinnacle's no-vig odds, and combines 2 to 7 of them from different matches at one bookmaker, showing each slip's total odds and combined EV.
Yes, when every leg has positive expected value and the legs are independent. The accumulator's EV is then (1 + EV1) × (1 + EV2) × … − 1, so three +2% legs make a +6.12% accumulator.
More legs compound the edge or the margin faster and make a win rarer. Three +2% legs at 1.80 win about 18% of the time, and each extra leg at 1.80 multiplies that chance by about 0.57. The builder lets you choose 2 to 7 legs.
An accumulator combines selections from different matches. A bet builder, or same game parlay, combines selections from one match; they are linked, so bookmakers price the combination with their own margin. The accumulator builder uses one leg per match.
The accumulator and parlay calculator on this page is free. The +EV accumulator builder, which builds slips from live value bets, is included in OddsFantasy's Classic plan.