General rules
- Odds are decimal. Fractions are read as a ÷ b + 1, American odds as X ÷ 100 + 1 (plus) or 100 ÷ X + 1 (minus).
- Precision: we calculate with full precision and round only the figures you see, to two decimal places.
- Void selections count at odds of 1.00. Lost selections make every bet that contains them return nothing.
- Bookmaker rules such as payout caps, dead heats and special bonuses are not included, because they differ between bookmakers.
Returns, accas and systems
| Calculator | Formula |
|---|---|
| Single | Return = stake × odds |
| Accumulator | Return = stake × product of all odds; bonus = profit × bonus % |
| System and full-cover | Every combination of the chosen sizes is one bet; return = sum over winning combinations of unit stake × product of their odds |
| Total stake mode | Unit stake = total stake ÷ number of bets |
Odds and probability
| Calculator | Formula |
|---|---|
| Implied chance | 100 ÷ decimal odds |
| Margin (overround) | Sum of 1 ÷ odds minus 100%; payout = 100% ÷ sum |
| Fair odds | Odds × sum of 1 ÷ odds |
| Expected value | EV% = chance × odds minus 1 |
| Kelly | Share = (chance × odds minus 1) ÷ (odds minus 1), times the chosen fraction |
Bonuses and trading
| Calculator | Formula |
|---|---|
| Free bet SNR | Return = amount × (odds minus 1) |
| Free bet SR | Return = amount × odds |
| Rollover | Wagering = multiple × base; cost = wagering × (1 minus (1 minus edge) to the power of legs) |
| Lay | Liability = lay stake × (odds minus 1) |
| Matched, qualifying | Lay stake = back stake × back odds ÷ (lay odds minus commission) |
| Matched, free bet SNR | Lay stake = amount × (back odds minus 1) ÷ (lay odds minus commission) |
| Hedge | Hedge stake = stake × original odds ÷ hedge odds |
| Cash out fair value | Stake × original odds ÷ current odds |
| Arbitrage and dutching | Stake on an outcome = total × (1 ÷ its odds) ÷ sum of 1 ÷ odds |
| Asian handicap | Quarter lines split the stake between the two neighbouring lines |
What we test
Each calculator is checked against hand-worked examples, the same ones you see on its page, before the site goes live. If you find a case where a result looks wrong, send us the inputs on the contact page.
Questions
Do you use live odds?
No. You type the odds. We never show live prices or fill them in for you.
Why might my bookmaker pay a little less?
Rounding, payout caps or a settlement rule such as a dead heat.