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
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Whilst the rule does compensate for withdrawn horses, there is an exception to this rule.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.
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 maths 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 more simple 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:
- If the horse is priced at odds of 15.0 or over, the price of your horse will not reduce
- 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 which the horses reduce by is usually around the same with the difference being minimal meaning over time it will be likely to even out. We have a detailed guide on what a betting exchange is and how it works, which is handy for players who are looking to learn more regarding these alternative platforms.
Learn More About Matched Betting At OddsMonkey
Rule 4 can change the way matched betting works slightly and can influence the amount of profit made. As odds change in a race, it is important to ensure that the prices and odds of tour horses remain matched even after a rule 4 has been applied. If this is not the case, your back and lay bet are not matched correctly and could potentially result in losses as opposed to locked in profits. This is just one of the many different components that can affect matched betting; we have a dedicated matched betting blog which can be handy for players who are interested in learning more about matched betting!
