Betting calculator
Rule 4 Calculator
Use this Rule 4 calculator to estimate how a deduction affects your horse racing winnings, adjusted return and adjusted profit.
Enter stake, odds and deduction
The calculator applies the deduction to the winnings and then adds the original stake back to show adjusted return.
A £10.00 winning bet at odds of 6.00 has £50.00 profit before deduction. A 20p Rule 4 deduction removes £10.00 from the winnings, leaving £40.00 adjusted profit.
What is Rule 4?
Rule 4 is a horse racing deduction applied when a horse is withdrawn after bets have already been placed. The deduction reduces winnings to reflect the changed market after the non-runner is removed.
The deduction is usually expressed as pence in the pound. For example, a 20p Rule 4 deduction means 20% is deducted from the winnings.
Rule 4 formula
Original profit = stake × (decimal odds − 1)
Deduction amount = original profit × deduction percentage
Adjusted profit = original profit − deduction amount
Adjusted return = adjusted profit + stake
Rule 4 example
Suppose you place £10 at decimal odds of 6.00. The original profit would be £50. If a 20p Rule 4 deduction applies, 20% of the profit is deducted.
| Calculation | Amount |
|---|---|
| Original profit | £50.00 |
| 20% deduction | £10.00 |
| Adjusted profit | £40.00 |
| Adjusted return including stake | £50.00 |
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Betting Maths calculators are designed to show the arithmetic behind the inputs you provide. A calculated return, probability, liability or expected value is not a prediction that an event will happen.
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Real settlement can also depend on bookmaker or exchange rules, non-runners, voids, liquidity, price movement and promotional terms.