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Rule 4 (deductions) calculator

When a horse is withdrawn before a race, bookmakers apply a Rule 4 deduction to winnings on bets already struck. Enter your odds, stake and the withdrawn runner's price to see the deduction, your adjusted odds and your adjusted return.

Your odds (decimal or fractional) Stake (£) Withdrawn horse's odds (decimal or fractional)

Why Rule 4 exists

If a runner is withdrawn after the market forms but before you can be given a fresh price, the remaining horses become more likely to win — so the odds you took are now too generous. Rule 4 (of the Tattersalls Committee) corrects this by deducting an amount from your net winnings (not your stake) based on how likely the withdrawn horse was to win: the shorter its price, the bigger the deduction.

The deduction is quoted in pence per £1 of winnings. Example: back a horse at 5.0 (4/1) with £10, and a 2.0 (evens) runner is withdrawn → 45p in the £ is deducted from the £40 winnings (−£18), so you'd win £22 plus your £10 stake back. Your stake is never touched — only winnings. This is a returns calculator, not a prediction.

Full Tattersalls Rule 4 deduction scale

Withdrawn horse's odds	Deduction (per £ of winnings)
3/10 or shorter	75p
2/5 – 1/3	70p
8/15 – 4/9	65p
8/13 – 4/7	60p
4/5 – 4/6	55p
20/21 – 5/6	50p
Evens – 6/5	45p
5/4 – 6/4	40p
13/8 – 7/4	35p
15/8 – 9/4	30p
5/2 – 3/1	25p
10/3 – 4/1	20p
9/2 – 11/2	15p
6/1 – 9/1	10p
10/1 – 14/1	5p
Over 14/1	No deduction

Deductions apply to net winnings only. Where more than one horse is withdrawn the deductions are combined (capped at 90p in the £). Some bookmakers publish minor variations — always check the settlement rules of your bookmaker.