# Rule 4 Calculator

The implementation of Rule 4 makes horse racing more complicated due to the rule changing odds before races begin. Therefore, here at OddsMonkey, we have created a specific calculator which can help players figure out what odds they must place after the Rule 4 deduction has taken place. We will look through what a Rule 4 deduction is, how the calculator helps users, and how the Rule 4 calculator can be used for matched betting specifically.

## What Is A Rule 4 Deduction?

One of the most common questions in horse racing is 'Why has my horse bet not returned as much as I expected?'. This usually is because of the Rule 4 deduction which is brought in to compensate for the withdrawal of a horse from a race.

When a horse withdraws from a race, all of the other horses will be reduced by a percentage due to there being fewer horses in the event, therefore boosting the chances of the remaining horses in the process. However, different-priced horses will result in different reductions. If a horse with low odds withdraws, then the other horses will ultimately reduce by a greater amount compared to a horse withdrawing with high odds.

The only exception to this rule is reserves. Most bookmakers will not apply a Rule 4 deduction when a reserve is withdrawn as they are not official runners. Here at OddsMonkey, we have a horse racing betting guide for everything horse racing when it comes to placing bets!

## How To Use The Rule 4 Calculator

The Rule 4 calculator is used when placing matched bets and is a vital tool for matched bettors.  In typical OddsMonkey fashion, we have created a calculator for players to use, which can make this overall experience easier.

Like with all other betting calculators on site, the Rule 4 calculator is simple to use with the back odds and the Rule 4 deduction needed, and the lay odds needed if a lay bet has been placed.

The Rule 4 calculator can be used to work out the odds of your horse after a Rule 4 deduction. We can find out both new back odds and new lay odds, which is vital for matched betting. For the new back odds, players must input the back odds and the rule 4 deduction. In contrast, the lay odds need the original lay odds and the reduction factor to find out the new odds. Finding these new prices is crucial to ensure that bettors are not losing out to the Rule 4 deduction.

To place a matched bet, players must place a back bet and a lay bet on the same event. Whilst using careful mathematics and strategy, players can ensure a return no matter the outcome as the odds will always be in favour of the player when matched betting techniques are used.

It is important to remember that the Rule 4 reduction only applies to bookmaker's odds, meaning odds at betting exchanges are affected in a different way. We have a blog piece describing everything players need to know about betting exchanges for players who need help figuring out how exactly these platforms work.

## Who Can Use Rule 4 Calculator

The Rule 4 calculator is available for any users who would need it, with the calculator being very simple in design and mechanics, making it not hard at all to use. It is worth noting though that the Rule 4 calculator is only used in horse racing specifically as the Rule 4 deductions are not present in any other sport.

## How Does The Rule 4 Calculator Link To Matched Betting?

As the Rule 4 Calculator can give back and lay bet odds, this automatically associates the calculator with matched betting as lay bets are included. For players who aren't too sure about what matched betting is or how it works, don't worry! Here at OddsMonkey, we have informative guides, many of which are housed on our matched betting blog, which break down this innovative approach to betting, as well as having some alternative sport-specific guides, such as our horse racing matched betting guide.

## Use The Rule 4 Calculator At OddsMonkey

The Rule 4 calculator is extremely useful when betting on horse racing as the odds can be entirely shifted when Rule 4 is in play. Make sure to use the calculator whenever this rule may be applied to ensure the best outcome for yourself.

There are plenty of other calculators available here at OddsMonkey besides the Rule 4 calculator too, with tools such as our single bet calculator and accumulator calculator being just two other examples which can be useful to any matched bettor.