Dilutions can be a bit confusing at first, the goal of this guide is to help clear some bits up. Before racing ahead and just looking for a chart or formula, it’s important to explain a couple of things, even if they add some confusion initially.

What is Dilution?

Dilution is taking a concentrated chemical and dissolving it in a solution (typically water), which is usually done to make the chemical ready for use. The amount you should dilute a chemical is most often displayed as a ratio, such as “1:15”.

How Dilution is Expressed

Dilution Ratios

The most common way to express dilution is with a Dilution Ratio. The dilution ratio 1:15 means that 1 part chemical is combined or added to 15 parts water. The good thing about dilution ratios is that they’re universal and unitless/dimensionless, meaning units (imperial vs metric) don’t matter. 1 oz chemical diluted by 15 oz water, 1 flagon chemical diluted by 15 flagons water, and so on, will all give the appropriate dilution.

Dilution Ratio vs. Dilution Factor

Now to add to the confusion. The example used so far has been a Dilution Ratio. Sometimes, 1:15 can actually refer to a Dilution Factor. In those cases, 1:15 as a factor would not be the same as a ratio and would in fact mean 1 part chemical to 15 parts total, meaning the “1” in a dilution factor refers to 1/15th (as opposed to 1/16th if it were a dilution ratio). Whilst Dilution Factor isn’t common, the problem with this is that unless the manufacturer states it, you’ve no idea whether they’re using Dilution Ratio or Dilution Factor.

Dilution Ratio is by far the most common and it’s what will continue to be used for examples in this guide. If it is ever unclear whether a manufacturer is using a Dilution Ratio or a Dilution Factor for a specific chemical, reach out to the manufacturer for clarification.

Dilution Percentages (%)

Fear not, percentages can be better than ratios. Firstly, the maths is easy (especially for metric users!), and there’s zero confusion on what the manufacturer means. 4% is 4% regardless of the measuring system – metric, imperial or some system you came up with yourself. 4% will be used as an example and because it’ll make life easier with the numbers, this bit will be in metric.

When given a percentage, it’s simply the desired concentration. If 4% were expressed as a Dilution Ratio, it would be 4:96, as this gives 100 total parts (i.e. 100%), 4 of which are chemical – 4 out of 100 is 4%. Simple.

PIR

Firstly, “PIR” = “Panel Impact Ratio”. Some manufacturers will say something like “4% PIR” – what this means is: when the product is on the panel it should be at 4% concentration. PIR is usually only used when referring to products applied via foam cannons, however the principle remains the same everywhere, and it’s common to see users say “4% PIR” as a way of saying “4% on the panel, regardless of how it’s applied”.

How to Dilute

Using Dilution Ratio

Using the 1:15 example (and using oz as the unit of measurement), take 1 oz of chemical and add it to 15 oz of water. This will result in 16 oz of diluted product. To make a gallon of diluted product, just multiply that up. There are 128 oz in a gallon, which when divided by 16 (the total parts of 1:15) gives 8. So, 1:15 could be expressed as 8:120 – this would mean taking 8 oz of chemical, and adding it to 120 oz of water, giving a gallon of diluted product.

Using Dilution Percentages (%)

1L is a common amount of diluted product to make, so for a 4% solution, simply take 40ml of chemical and top up to 1L. This is where metric and percentages shine, as in the real world there are far fewer numbers to work with. And because most containers have markers to show the volume inside, it’s simply a case of adding the required chemical amount and topping up to the 1L mark.

The formula for this is:
(Desired amount of final product) * percentage (where 4% would be 0.04 as a decimal) = (amount of concentrated chemical required)

For example:
1000ml final product * 0.04 = 40ml of concentrated chemical

Using PIR

If applying the product via a sprayer, then it’s simply a case of diluting it that amount and having at it, similar to using Dilution Percentages.

If using a foam lance, this is NOT the concentration in the bottle! Please see the guides on foaming and PIR to figure out what should be done in this instance, because foam cannons will further dilute whatever is in the foam bottle.

Additional Tools

A chart to help visualise and convert some ratios:

Omni Calculator

This website is really useful for calculating dilutions: https://www.omnicalculator.com/everyday-life/dilution-ratio

Simply tell it how much to be created as well as the Dilution Ratio, and it gives the numbers in the chosen units.

ChatGPT

ChatGPT (https://chat.openai.com/) can also make a chart. As ChatGPT can occasionally give incorrect information, make sure you verify or double check before proceeding with the information it provides.