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When a horse is withdrawn from a race after your bet has been placed, bookmakers apply a Rule 4 deduction that reduces your winnings. This calculator works out your adjusted profit and adjusted return instantly — enter your stake, the decimal odds you took, and the deduction in pence per pound.
What Is Rule 4 in Horse Racing?
Rule 4 is a horse racing betting rule that gives bookmakers the right to reduce winnings when a horse is officially withdrawn from a race after bets have already been placed. The name refers to Rule 4(c) of Tattersall’s Rules, which governs betting settlement standards in British horse racing.
When a horse is removed from a race, the remaining runners become statistically more likely to win. Market prices shorten to reflect the smaller field, but if your bet was struck before the withdrawal was announced, you would be receiving odds that no longer fairly represent the race. The Rule 4 deduction bridges this gap, compensating for the change in probability by reducing the profit on any winning bet.
The deduction is expressed as pence in the pound. A 20p Rule 4 means 20 pence is removed from every pound of profit earned. A 75p deduction — reserved for cases where a very short-priced favourite withdraws — takes 75p from every pound of winnings, reflecting the much greater impact that horse’s removal has on the market.
When Does Rule 4 Apply?
A Rule 4 deduction is triggered when a horse is declared a non-runner after bets have been accepted on that race. If the horse is removed before markets open, no deduction applies because odds will already reflect the reduced field. The timing of the declaration and the price of the withdrawn horse both determine the level of deduction applied.
Most bookmakers do not apply Rule 4 to reserve horses, as these are not considered official runners. The rule applies to winning bets only — if your selection loses, the deduction has no effect and your stake is settled in the usual way.
At betting exchanges, the approach is different. Exchanges typically void bets on non-runners and return stakes rather than applying a deduction, though the exact treatment depends on the exchange’s rulebook and when the non-runner is declared.
The Rule 4 Formula
The calculation follows four steps, all working from the profit rather than the total stake. Here is the formula the calculator uses:
Worked Rule 4 Calculation Example
A £10 bet is placed at decimal odds of 6.00. Before the race, a short-priced runner is declared a non-runner and a 20p Rule 4 deduction is applied. Here is the full calculation:
| Step | Calculation | Result |
|---|---|---|
| Original profit | £10 × (6.00 − 1) | £50.00 |
| Deduction amount (20%) | £50.00 × 20% | −£10.00 |
| Adjusted profit | £50.00 − £10.00 | £40.00 |
| Adjusted return (stake included) | £40.00 + £10.00 | £50.00 |
Rule 4 Deduction Scale
The size of the deduction is directly linked to the odds of the withdrawn horse at the time of removal. The shorter the non-runner’s price, the bigger the deduction — because a heavily fancied horse being taken out of the race has a much greater effect on the remaining market than a 25/1 shot being removed.
The table below is based on the standard Tattersall’s Rule 4(c) deduction schedule used as the benchmark across UK racing. Individual bookmakers may apply slightly different bands — always verify with your bookmaker’s terms.
| Non-runner’s starting price (fractional) | Rule 4 deduction (pence in £) |
|---|---|
| 1/10 or shorter | 75p |
| 2/11 to 1/5 | 70p |
| 2/9 to 1/4 | 65p |
| 3/10 to 3/8 | 60p |
| 2/5 to 4/9 | 55p |
| 1/2 to 8/15 | 50p |
| 8/13 to 4/5 | 45p |
| 5/6 to evens | 40p |
| 11/10 to 6/4 | 35p |
| 13/8 to 2/1 | 25p |
| 85/40 to 3/1 | 20p |
| 10/3 to 4/1 | 15p |
| 9/2 to 11/2 | 10p |
| 6/1 to 9/1 | 5p |
| 10/1 or longer | No deduction |
Rule 4 and Matched Betting
For matched bettors, a Rule 4 deduction creates an imbalance between the back bet settled at a bookmaker and the lay bet placed at a betting exchange. Because bookmakers reduce the winning back bet by the deduction percentage while exchanges typically void lay bets on non-runners and return the stake, the lay stake calculated before the withdrawal may no longer offset the back bet correctly.
This is why a Rule 4 calculator is a practical tool in the matched betting workflow. After entering the adjusted figures, you can see whether the qualifying loss or free-bet profit has moved enough to require action. When a well-fancied horse is withdrawn and a large deduction applies, the difference can be meaningful. When a 10/1 shot is removed with no deduction, the position remains unchanged.
Most matched betting calculators include a Rule 4 field for exactly this scenario. The back odds are adjusted downward by the deduction percentage before the lay stake is recalculated, keeping the overall position as close as possible to the intended outcome.
Rule 4 vs No-Runner Money-Back Promotions
Some bookmakers run no-runner money-back promotions on selected races or markets, where stakes are refunded as a free bet if a non-runner is declared. In these cases, the Rule 4 deduction may not apply in the usual sense — instead, bets are voided or refunded. Always read the promotion terms carefully, as the standard Rule 4 settlement and a promotional no-runner refund are separate things governed by different terms.
Rule 4 Calculator – Frequently Asked Questions
Does Rule 4 apply to losing bets?
No. Rule 4 deductions only affect winning bets. If your selection loses its race, the deduction is irrelevant — there are no winnings to reduce, and the bet is settled as a normal loss.
Is the Rule 4 deduction taken from the stake or the winnings?
The deduction is always taken from the profit (winnings) only, not from the original stake. Your stake is returned in full if your selection wins. For example, a 20p Rule 4 on a £10 bet at 6.00 removes 20% from the £50 profit — a £10 deduction — leaving £40 adjusted profit plus the £10 stake returned, for a total of £50.
How do I convert a fractional Rule 4 deduction to a percentage?
The pence-in-the-pound figure converts directly to a percentage. A 20p deduction is 20%, a 35p deduction is 35%, and a 75p deduction is 75%. Simply divide the pence figure by 100 and multiply by your original profit to find the amount deducted.
Can more than one Rule 4 deduction apply to the same race?
Yes. If multiple horses are withdrawn from the same race, deductions from each non-runner are combined. Most bookmakers cap the total combined deduction at 75p in the pound regardless of how many horses are removed, but this varies — always check your bookmaker’s terms on multiple non-runners.
Does Rule 4 apply to each-way bets?
Yes. Rule 4 applies to both the win part and the place part of an each-way bet separately. Each portion is treated as its own bet, and the same deduction percentage is applied to the profit on each. It is also worth noting that the number of places offered may be reduced if enough horses are withdrawn, so check the revised place terms with your bookmaker.
Does Rule 4 apply to betting exchange wagers?
Not typically in the same way. Betting exchanges usually void bets on declared non-runners and return stakes to both sides rather than applying a profit deduction. The exact treatment depends on the exchange’s rules and whether the non-runner is declared before or after in-running betting begins. Always check the specific exchange’s terms.
How does Rule 4 affect free bets?
If a winning free bet is subject to a Rule 4 deduction, the same deduction percentage is applied to the profit portion. Because most bookmakers issue free bets on a stake-not-returned (SNR) basis, the stake element is not included in the settlement, so only the adjusted profit is paid out. Always confirm how your bookmaker handles free bet settlements under Rule 4 within its terms.
What is the maximum Rule 4 deduction possible?
The maximum deduction under standard Tattersall’s guidelines is 75p in the pound, applied when the withdrawn horse was priced at 1/10 or shorter. Even when multiple non-runners are declared, most bookmakers cap the combined deduction at this 75p ceiling, meaning you always receive at least 25% of your original profit if your bet wins.
This calculator is for informational purposes only. Actual Rule 4 settlement is determined by your bookmaker’s terms and conditions and may differ from the figures shown.
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