One of the most common questions that arises mainly during horse racing betting is “Why is the return on my bet not what I expected?” The most common reason is the implementation of Rule 4, which applies when another horse withdraws and therefore reduces the price of the horse you are backing. In OddsMonkey, we will look at what a rule is, why it is needed, and how to use the tools provided by OddsMonkey when applying rule 4.

What are horse racing rules 4

As stated previously, Rule 4 applies if a horse in a race withdraws and does not compete. This will certainly affect the race as there will be one less horse in the race, thus affecting the odds of the race. Rule 4 was introduced to compensate for the withdrawal of a horse, it will reduce the odds of other horses running in upcoming races as horses now running will have a better chance of winning overall.

For example, if a player bets on a horse at odds of 6.0 and the favorite is priced at 2.0, if the favorite withdraws from the race, the price will decrease as the horse’s probability of winning increases. The amount reduced is the deduction under Rule 4. To find out more about the sport, check out our separate horse racing betting guides and horse racing matched betting guides.

Why is Rule 4 needed?

Horse racing requires Rule 4 to ensure that odds and rewards remain fair, even if unfortunate circumstances arise, such as a horse withdrawing from a race. Horses at different prices will result in different discounts. If a low-odds horse quits, your horse’s price will drop more than a high-odds horse.

While the rule does compensate horses for withdrawing, there is an exception to the rule. Reserve racing is most common in Irish horse racing, but can also be seen in some British races. Most bookmakers will not apply the Rule 4 deduction when a reserve is withdrawn as they are not an official entrant. However, some bookmakers (such as Coral and Ladbrokes) do use this rule in these situations, so please be careful when placing bets with certain bookmakers.

When can Rule 4 be triggered?

Rule 4 can be activated for many reasons, most of which are completely random and unpredictable. Here are some of the most common reasons for triggering Rule 4:

• Non-Runner – If a horse withdraws on race day, a Rule 4 will most likely be declared, which is the most common reason for using a Rule 4.

• Weather Conditions – Some horses are not suited to running in certain conditions, so some horses will withdraw from the race in certain adverse weather conditions, such as heavy rain. This is usually done to protect the horse.
• Veterinary Intervention – A veterinarian may recommend withdrawing the horse from racing once the betting market opens.
• Jockey Issues – If a horse is declared unfit because the jockey was injured in a previous race, Rule 4 may be invoked.

Rule 4 Example

Let’s look at a real-life example of how the Rule 4 deduction affects your horse racing bets. For example, you place a £10 bet on a horse at odds of 4/1 and just before the race begins, the other horse is withdrawn at odds of 7/1. Let’s take a step-by-step look at how Rule 4 deductions will affect betting:

• Potential bonus: £40
• Rule 4 7/1 Deduction for non-runners: 10p per pound
• Deduction amount: £40 x 0.10 = £4
• Adjusted return: £40 – £4 = £36
• Total return = £36 + £10 shares = £46

Rule 4 Calculator

In typical OddsMonkey fashion, we have a calculator for players to use when applying Rule 4. Use our Rule 4 Calculator to help work out your horse’s odds after Rule 4 deductions. There are formulas for players to calculate by themselves, but due to the complexity of the mathematical formulas, it is recommended to use a calculator.

(Decimal odds – 1) X (1 – Decimal reduction factor) + 1

This is the formula used by the Rule 4 calculator; however, the calculator makes things much simpler as the player only needs to enter the back odds and betting odds, and then enter the Rule 4 deduction and reduction factors to create the new odds the player desires.

If we use the previous example of a horse with odds of 6.0, the new odds would be 3.75 based on this formula. There are two other important factors to consider:

1. Your horse’s price will not be reduced if its odds are 15.0 or above
2. Rule 4 only applies to bookmaker odds; there is a different way of calculating exchange rate changes in prices.

Rule 4 on the exchange

When Rule 4 comes around, betting exchanges work differently than bookmakers in that each horse is given a “reduction factor” based on the predicted price and is displayed as a percentage. Once a horse withdraws, the reduced percentage will apply to all other horses in the race.

If you place a matched bet on horse racing, the horse racing will usually be reduced by roughly the same amount, with very little difference, meaning it will likely even out over time.

How to Prepare for Rule 4 Deductions

Rule 4 deductions can occur after a bet has been placed, which means it is difficult to avoid them as they can occur at any point in any match. Be sure to keep these tips in mind when planning for this deduction.

✅ Watch out for odds changes – If there is a big change in the odds, it could be a sign that one of the contestants is about to drop out.

✅Consider deductions before placing a bet – Before placing a bet, consider the possibility of deductions occurring and make sure you understand all possibilities of your bet.

✅ Watch for announcements – When you place your bet, be sure to pay attention to any announcements made during the race as these will notify you if a horse withdraws.

Learn more about matched betting at OddsMonkey

Rule 4 can slightly change the way matched betting works and affect the amount of profit. As race odds change, it is important to ensure that prices and odds for Tour horses remain matched, even after Rule 4 has been applied. If this is not the case, your back bet and outside bet are not matched correctly and could result in a loss instead of locking in a profit. This is just one of many factors that influence matched betting; we have a dedicated matched betting blog handy for players interested in finding out more!

Rule 4 FAQ

Because Rule 4 derivation can be confusing, there are some frequently asked questions surrounding the topic, which we’ll discuss here.

What happens if multiple horses withdraw from the race?

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

Rule 4 Will deductions affect the bet amount?

No, Rule 4 deductions only affect profits from successful bets. If your horse wins, you get your original stake back through the payoff.

Do all bookmakers use Rule 4?

All bookmakers use Rule 4 deductions as it is an industry standard provision.