What Is Rule 4 In Horse Racing?

One of the most common questions that comes around mainly during horse racing bets is, ‘Why has my bet not returned as much as I expected?’ The most common reason for this will be the implementation of Rule 4, which applies when another horse withdraws and, therefore, reduces the price of the horse you backed. Here at OddsMonkey, we will look at what the rule is, why it is needed, and how to use the tools available to you here at OddsMonkey in the event of Rule 4 being applied.

What Is Rule 4 in Horse Racing

As previously mentioned, Rule 4 applies when a horse in a race withdraws and will not compete. This will inevitably affect the race, as there is one less horse in the race, therefore affecting the odds of the race.  Brought in to compensate for a withdrawal of a horse, Rule 4 will reduce the odds of other horses to then match the race that will happen as the horses now running will have an overall better chance of winning. 

For example, if players back a horse at odds of 6.0 and the favourite horse is priced at 2.0 if the favourite pulls out of the race, there will be a reduction in price due to the probability of the horse winning increasing. How much it is reduced by is the Rule 4 deduction. To learn more about the sport, check out our separate horse racing betting guide and our horse racing matched betting guide.

Why Is Rule 4 Needed?

Rule 4 is needed in horse racing to ensure the odds and returns are kept fair, even if unfortunate circumstances arise, such as horses withdrawing from the race. Different-priced horses will result in different reductions. If a horse with low odds withdraws, then your horse’s price will be reduced by a greater amount compared to a horse with high odds.

Whilst the rule does compensate for withdrawn horses, there is an exception to this rule. Reserves are most common in Irish horse racing but can be seen in certain UK races. Most bookmakers will not apply the Rule 4 deduction when a reserve withdraws, as they are not official runners. However, some bookmakers, such as Coral and Ladbrokes, do use the rule in these circumstances, so make sure to be careful when placing your bet with certain bookmakers. 

When Might Rule 4 Be Triggered?

There are plenty of reasons why the Rule 4 might be activated, with most of them being completely random and unable to be predicted. Here are some of the most common reasons for the Rule 4 to be triggered:

• Non-Runners – If a horse is pulled out on the day of the race, the Rule 4 is likely to be declared, and this is the most common reason for the Rule 4 to be used.

• Weather Conditions – Some horses are not suited to run in specific conditions, so some horses are withdrawn from the event in some adverse weather, such as heavy rainfall. This is usually done to protect the horse.
• Vet Intervention – It’s possible that a vet may recommend that a horse be withdrawn from a race after the betting market has opened. 
• Jockey Issues – A Rule 4 can be invoked if a horse is declared a non-runner because a jockey has been injured in a previous race.

Rule 4 Example

Let’s look at a real example of how the Rule 4 deduction can affect your horse racing bets. For example, you place a £10 bet on a horse at odds of 4/1, and just before the race starts, a different horse is withdrawn at the odds of 7/1. Let’s look at a step by step by step guide of how the Rule 4 deduction would affect the bet:

• Potential Winnings: £40
• Rule 4 Deduction for a 7/1 non-runner: 10 pence per pound
• Amount Deducted: £40 x 0.10 = £4
• Adjusted Return: £40 – £4 = £36
• Total Returns = £36 + £10 stake = £46

Understanding how much the Rule 4 will deduct can be quite confusing, which is why we have a table you can refer to when this rule is enforced:

Rule 4 Deduction Table

The Rule 4 Calculator

In typical OddsMonkey fashion, we have a calculator available for players to use in the event of Rule 4 being applied. Use our Rule 4 calculator to help work out the odds of your horse after a Rule 4 deduction. There is a formula for players to work out the deduction themselves, yet using the calculator is recommended due to the complicated mathematical formula used. 

(Decimal Odds – 1) X (1-Decimal Reduction Factor) +1

This is the formula used for the Rule 4 calculator; however, the calculator makes it much simpler as players only need to input the back and lay odds, then the Rule 4 deduction and the reduction factor to then create the new odds the player would need.

If we use the previous example of a horse with the back odds of 6.0, the new odds will be 3.75 with this formula. There are two other important factors to take into account:

1. If the horse is priced at odds of 15.0 or over, the price of your horse will not be reduced
2. Rule 4 only applies to bookmakers’ odds; there is a different way to calculate the exchange change in price.

Rule 4 At Exchanges

Betting exchanges work in a different way than bookmakers when a rule 4 comes into the picture, as each horse is given a ‘Reduction Factor’ based on a forecast price and shown as a percentage. Once a horse is withdrawn, the reduction percentage will then apply to all the other horses in the race. 

If you have matched bets on the horses, the amount that the horses reduce by is usually around the same, with the difference being minimal, meaning over time it will be likely to even out. 

How To Be Prepared For Rule 4 Deductions

The Rule 4 deduction can happen after bets have been placed, meaning it can be quite hard to avoid them, as they can happen in any race at any point. It is important that you plan for this deduction by keeping these tips in mind.

✅Keep an eye on shifting odds – If there is a big change in odds, then it could indicate that one of the runners is about to be withdrawn.

✅Consider the deduction before placing the bet – Before placing the bet, take into account the possibility of the deduction taking place, ensuring that you are aware of all the possibilities from the bet.

✅Look out for announcements – As you are placing bets, make sure to look out for any announcements that have been made on the race, as these will inform you if any horses have pulled out.

Learn More About Matched Betting At OddsMonkey

Rule 4 can slightly change how matched betting works and influence the amount of profit made. As odds change in a race, it is important to ensure that the prices and odds of the tour horses remain matched even after a Rule 4 has been applied. If this is not the case, your back and lay bets are not matched correctly and could potentially result in losses as opposed to locked-in profits. This is just one of the many components that can affect matched betting; we have a dedicated matched betting blog that can be handy for players who are interested in learning more!

Rule 4 FAQs

As the Rule 4 deduction can be confusing, there are some frequently asked questions surrounding the topic, which we will go through here.

What happens if there are multiple horses withdrawn from a race?

There can be more than one Rule 4 deduction; however, the total of a Rule 4 deduction cannot exceed 90%.

Does the Rule 4 deduction affect the betting stake?

No, the Rule 4 deduction only impacts the profits from a successful bet. If your horse does win, you will get your original stake back with the returns.

Do all bookmakers use the Rule 4?

All bookmakers use the Rule 4 deduction as it is an industry-standard regulation.