The Mathematics
Convert every fractional quote separately before multiplying. For 3/1 and 2/1, the decimal calculation is 4.00 × 3.00 = 12. Combined decimal odds already include the returned stake, so the equivalent combined fractional price is 11/1. Multiplying the raw fractional profit odds would omit stake rollover and understate the payout. A double is equivalent arithmetically to rolling the entire return from one successful leg into the next, not rolling only the first leg's profit.
Each decimal price = fractional numerator ÷ denominator + 1
Combined decimal odds = product of every leg's decimal price
All-win return = cash stake × combined decimal odds
Profit = return − original cash stake
If any leg loses: return = £0
Worked Example
Worked double example: 3/1 and 2/1, with a £10 total stake. Decimal multiplication is 4.00 × 3.00 = 12. If all 2 selections win, return is £10 × 12 = £120; profit is £120 − £10 = £110. If any selection loses, return is £0 and the loss is £10. No deductions, dead heats, free-bet conditions or bonuses are assumed.
How do I enter the double inputs?
The form has Selection 1 Odds, Selection 2 Odds and Stake. Enter fractional prices with a slash in both odds rows, then enter the whole cash amount risked on this one double. There is no unit-stake multiplication across two bets: a £10 double costs £10.
Use the accepted price for every leg and check that the completed row list matches the slip. Do not enter a quoted combined price into an individual selection row as well as entering the other legs, because that would multiply some prices twice. The calculator does not retrieve starting prices, approve combinations, place bets or know the final results. Its all-win total is a conditional illustration. To compare with a settled ticket, first identify losses, voids and any adjustments to individual prices.
How does a double compare with separate or covered bets?
Two £5 singles at 3/1 and 2/1 cost £10 and return £35 if both win. If only the 3/1 horse wins, they return £20 and make £10 profit overall. The £10 double instead returns £120 when both win but nothing when either loses. Compare those patterns at equal total outlay, not a £10 double against two £10 singles.
A double is the smallest multiple. A treble adds a third required winner; a Trixie uses three selections but covers three doubles and a treble as four separately staked lines. Adding a third horse to a double is not the same as buying cover for a losing leg.
What happens when a double leg loses or is void?
If the 3/1 leg wins and the 2/1 leg loses, the double returns £0. There is no separately payable £40 single on the first horse. If the second leg is void under ordinary non-runner terms instead, the double usually reduces to a £10 single at 3/1, returning £40 if that remaining horse wins.
The ordinary void-leg arithmetic treats the removed leg as decimal 1.00, leaving the original stake running through the remaining legs. If all legs are void, the usual cash outcome is a stake refund. Ante-post and special-market rules may differ. This form does not provide a void selector; it is better to recalculate the valid remaining combination and confirm the operator's settlement than to input a fictitious winning result.
Which double adjustments need separate checking?
Rule 4 reduces the profit odds of the affected race leg rather than simply cutting the final ticket return by a guessed percentage. For a leg at 4/1 with a 25p deduction, use adjusted decimal odds of 1 + 4 × 0.75 = 4.00, then multiply by the other decimal legs. A dead heat also reduces the return attributable to that leg under the relevant rules. This calculator has no integrated controls for either adjustment.
Each way doubles are normally two linked lines, win-to-win and place-to-place, not every possible mixed finishing pattern. They cost twice the unit stake and need each race's place terms. Exchange commission, stake-not-returned free bets, promotional insurance, maximum payouts and best odds guaranteed are also outside this form. The reciprocal of the combined odds is only a market-implied percentage. It is not the actual chance of success, and multiplying genuine probabilities would require an independence assumption or a suitable joint model.
Popular questions about this calculator
What is a double bet?
A double is one bet on two selections, both of which must win. It is not two separately staked singles. The stake is placed once on the linked line. Successful early legs do not produce payable singles if a later leg loses; the whole combination must satisfy its winning conditions.
How do I calculate double odds?
Convert each fractional price to decimal, then multiply all decimal prices. For 3/1 and 2/1, 4.00 × 3.00 gives decimal 12, equivalent to fractional 11/1. Do not multiply fractional numerators alone, because the stake must roll through each leg.
What does the example £10 double return?
At 3/1 and 2/1, all 2 winners return £120 including the original £10 stake. Profit is £110. If any ordinary leg loses the return is £0. This assumes cash staking and no settlement deductions or promotional conditions.
Does a double pay if one selection loses?
No, not under ordinary all-win terms. If the 3/1 leg wins and the 2/1 leg loses, the double returns £0. There is no separately payable £40 single on the first horse. If the second leg is void under ordinary non-runner terms instead, the double usually reduces to a £10 single at 3/1, returning £40 if that remaining horse wins. Any insurance or refund promotion is separate from the base bet and needs its own qualifying rules; the calculator does not apply those offers.
What happens to a double with a non-runner?
Under ordinary non-runner rules a void leg is removed and the same stake continues on the smaller multiple. It is not treated as a losing leg. Ante-post and special-market conditions can differ. The widget does not automatically detect withdrawals or provide a void-result switch.
Can I use this double calculator for each way bets?
No. This form calculates a win-only linked line. Each way uses separate win and place multiples, normally settled win-to-win and place-to-place. You need every selection's place fraction and eligibility, and twice the unit stake, rather than the win-only figure shown here.
Can two horses in the same race form a win double?
Ordinary outright win doubles are normally made from different events. Two horses in the same race cannot both be sole winners, and related-contingency restrictions can also apply. This calculator only multiplies entered prices; it does not validate whether the bookmaker will accept that combination.
Do the double odds show the true chance of winning?
No. Odds supply a conditional payout and a market-implied percentage. They are not calibrated probabilities. Even when genuine single-selection chances are available, simply multiplying them is justified only for independent outcomes; related events require a joint assessment rather than this payout calculator.
Does the double calculator include Rule 4 and dead heats?
No. Those changes must be assessed for the affected leg under the operator's rules. Reducing the final ticket profit with one blanket percentage can be wrong. Use the separate settlement tools for simple single-leg checks, and confirm the complete multiple settlement with the bookmaker.
How much should I stake on a double?
There is no universal safe stake produced by a returns calculator. Decide an affordable total spending limit first, then compare conditional returns without increasing the limit to chase a payout. The full stake can be lost when one required selection fails, even after earlier legs have won.
Official rules and further reading
These operator references explain bet structures and settlement rules. They are not endorsements, and the terms attached to your accepted bet take precedence. Worked amounts on this page are illustrative arithmetic, not live odds or promised outcomes. Only gamble money you can afford to lose; a returns tool does not make a bet safe.