What Rule 4 does to a winning racing bet
A £10 win single at 4/1, a withdrawn favourite, and the deduction scale worked through.
You back a horse at 4/1 with £10, then another runner is withdrawn.
You stake £10 to win on a horse at 4/1 in a race with six runners. Before the race starts, one of the other runners is withdrawn. Your own horse is still running, so your bet stands. What changes is the chance that every remaining horse wins, which went up the moment a rival dropped out, and Rule 4 is how bookmakers adjust for that.
The withdrawn horse was 7/4, so the scale takes 35p in every pound.
The deduction depends on the withdrawn horse’s price when it came out. The favourite here was 7/4, which sits in the band that deducts 35p from every pound of winnings. The scale used on this page is the one published by Racing Post; bookmakers publish their own tables and the edges of the bands can differ, so the operator’s terms decide a real bet.
Your £40 of winnings lose 35p in the pound and become £26.
At 4/1 your £10 stake would win £40. Rule 4 takes 35p off every pound of that, which is £14, so the winnings become £26. The deduction applies to win bets and to each-way and place bets alike, according to William Hill’s terms, and it only touches the winnings.
The stake is safe: £36 comes back instead of £50.
Your original stake is never reduced. The £10 comes back in full, added to the £26 of reduced winnings, so £36 returns where £50 would have without the deduction. The bet still wins and still pays, only at a smaller price than the one you took. Sporting Life makes the same point: the full stake is returned whatever the level of reduction.
A long-priced withdrawal costs little: at 10/1 the deduction is 5p.
If the withdrawn horse was a 10/1 outsider, the deduction is only 5p in the pound. Your £40 of winnings fall by £2 to £38, and with the stake £48 comes back. A horse that was never likely to win barely changes the odds for everyone else, which is why the scale gives it the smallest cut.
A very short-priced one costs most: 90p in the pound at 1/9.
At the other end, a withdrawn horse priced 1/9 or shorter was almost certain to win, and the deduction is the largest on the scale: 90p in the pound. Your £40 of winnings fall to £4, and £14 comes back with the stake. The race changed completely when that horse came out, and the scale reflects it.
Two withdrawals add up, but the total stops at 90p in the pound.
When two horses are withdrawn, their deductions are added together, so a 1/4 horse (80p) and a 2/5 horse (70p) would come to 150p. Most published rules cap the total at 90p in the pound, as At The Races’ guide states. Coral’s shop rules give a different cap, 95p, so the operator’s own terms are the final word.
Without it, 4/1 would pay as if the 7/4 horse were still running.
A price of 7/4 stands for a chance of about 36 per cent, as the market priced the race. When that horse leaves, that share of the race is gone, yet the 4/1 on your bet was set with it still in. Without Rule 4 you would be paid for a race that no longer exists. The deduction is a rough, standard way of closing that gap.
Checked across all 18 bands: the deduction never rises as the price lengthens.
To check the scale’s logic, the page walks through all 18 price bands of the Racing Post table, from 1/9 and shorter at 90p to the longest prices at 5p. Going down the list, the withdrawn horse’s price gets longer and the deduction never rises: it rose zero times. That is the shape the rule is meant to have, a bigger cut the more the withdrawn horse mattered.
Sources: Racing Post bet calculator: Rule 4 deduction table · Racing Post: Rule 4 explained for occasional punters · William Hill help centre: Rule 4 Deduction Explained · Sporting Life: What is Rule 4? · At The Races: bet calculator and Rule 4 guide
Next: work out a Rule 4 deduction for your own bet with the Rule 4 calculator