This Rule 4 calculator works out how much a non-runner takes off your winnings. You backed a horse at 7/2 for £10, and the 3/1 second favourite is withdrawn at the start. The deduction is 25p in the pound, so your £35 of winnings becomes £26.25 and you get £36.25 back, not £45.
Your stake is never touched. Only the winnings come down. The free calculator above uses the standard Tattersalls table and handles a second withdrawal too.
Rule 4 calculator: the deductions table
The deduction depends on the withdrawn horse’s price at the time it came out:
| Withdrawn horse’s price | Deduction |
|---|---|
| 1/9 or shorter | 90p |
| 2/17 to 2/11 | 85p |
| 1/5 to 1/4 | 80p |
| 2/7 to 3/10 | 75p |
| 1/3 to 2/5 | 70p |
| 4/9 to 8/15 | 65p |
| 4/7 to 8/13 | 60p |
| 4/6 to 4/5 | 55p |
| 5/6 to 10/11 | 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 |
| Longer than 14/1 | No deduction |
Why Rule 4 exists
With a strong horse gone, everything left in the race has a better chance. Your 7/2 was priced against a field that included the 3/1 shot. Without it, the horse might be 5/2. Rule 4 brings your winnings roughly into line with the new market, and the “Your odds after the deduction” line shows that: 7/2 minus 25p is about 21/8.
If you took the starting price, Rule 4 doesn’t apply. The SP is formed after the withdrawal, so it already reflects the smaller field. Bets placed after a new market is formed aren’t affected either.
Two non-runners
When more than one horse is withdrawn, the deduction comes from their combined price, and it’s capped at 90p. A 3/1 and an 8/1 together are about a 36% chance, close to 7/4, so the deduction is 30p, not 25p plus 10p. Tick “A second horse was withdrawn” to see it. On the example bet, that leaves £24.50 of winnings.
Each-way bets lose the same pence on both parts. For settling whole multiples with a Rule 4 on one leg, use the horse racing bet calculator; for ties at the finish, the dead heat calculator.
Non-runners happen in most race meetings. Check the deduction before you count the winnings. BeGambleAware.org is free and confidential if it stops being fun.