What is Rule 4?
Rule 4 is the industry-wide rule that adjusts your bet's price when a horse you didn't back is withdrawn after the market opens. The deduction reflects how much shorter the field has become, because removing a fancied non-runner makes every other horse more likely to win, the bookmaker takes some of your potential winnings as a Rule 4 deduction. The amount is set by the non-runner's SP at the time of withdrawal: 5p per pound at very short prices, up to 90p+ for last-minute favourite withdrawals.
Your bet, before Rule 4
What price you took. Type fractional (5/1), decimal (6.00) or American (+500).
= 6.00 decimal
Add a stake to see the cash difference, or leave blank to compare just the new odds.
Rule 4 deduction
The pence-per-pound the bookmaker deducts from your winnings because a non-runner was withdrawn after you placed the bet. The amount is set by industry rules based on the non-runner's SP: common values are 5p, 10p, 25p and 40p.
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What is Rule 4 in horse racing?
Rule 4 (sometimes "Tattersalls Rule 4") is an industry-wide rule that reduces the odds on your bet when a horse is withdrawn from the race after the market opens but before the off. The deduction reflects the fact that the field is now smaller: every remaining runner has a higher chance of winning, so the bookmaker recovers some of the price they originally offered.
When does Rule 4 apply?
Whenever a horse you didn't back is officially withdrawn from the race after you placed your bet. If you backed the non-runner, your bet is voided and your stake refunded: Rule 4 doesn't apply. If your horse wins, the original price is reduced by the Rule 4 deduction in pence per pound of profit.
How is the Rule 4 deduction calculated?
The deduction is set by the price of the withdrawn horse at the time of withdrawal, on the Tattersalls Rule 4 sliding scale: 1/9 or shorter = 90p in the pound; 1/4 to 1/5 = 80p; 2/5 to 1/3 = 70p; 8/13 to 4/7 = 60p; 20/21 to 5/6 = 50p; evens to 6/5 = 45p; 5/4 to 6/4 = 40p; 13/8 to 7/4 = 35p; 15/8 to 9/4 = 30p; 5/2 to 3/1 = 25p; 10/3 to 4/1 = 20p; 9/2 to 11/2 = 15p; 6/1 to 9/1 = 10p; 10/1 to 14/1 = 5p; over 14/1 = no deduction.
Does Rule 4 affect place returns on each-way bets?
Yes. The deduction is applied to both the win and place parts of an each-way bet. The reduced win-part odds also reduce the place-part odds (which are typically 1/4 or 1/5 of the win odds). Use the each-way calculator alongside this Rule 4 calculator to see the full settlement.
What are typical Rule 4 deduction amounts?
Most punters see the smaller deductions: 5p (when a 10/1 to 14/1 horse is withdrawn), 10p (6/1 to 9/1), 15p (9/2 to 11/2), 20p (10/3 to 4/1) or 25p (5/2 to 3/1). Heavier deductions need a shorter-priced withdrawal: 40p means a 5/4 to 6/4 horse came out, and anything above 40p requires a withdrawn horse priced around 6/5 or shorter, which usually means a market-leading favourite came out very late.
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