No patience for formulas? Jump straight to the dilution calculator, enter your ratio and bottle size, and you see exactly how much concentrate and water you need. Want to understand it and never doubt again? Read on.
Diluting means mixing a concentrated product with water in a fixed ratio. You read that ratio as 1:X, meaning one part product to X parts water. The label of a snow foam, APC or shampoo says something like 1:10, 1:4 or 1:200. Get the ratio right and you get the most out of your product, far cheaper than ready-to-use bottles. Get it wrong and the product either does not work or you waste concentrate.
How to actually dilute: the formula
The whole trick is one word: total. At 1:10 you mix 1 part product with 10 parts water. Together that is 11 parts, not 10. Most people forget that extra part.
The formula is simple. First add up the parts: 1 plus X. Then divide your total volume by that number, which gives the size of one part. The product is always one part.
An example. You want to make up 1 litre (1000 ml) at 1:10. Add up: 1 plus 10 is 11 parts. Divide: 1000 divided by 11 is 91 ml per part. So you put 91 ml of product in the bottle and top it up to 1000 ml with water. Not 100 ml, because that would be counting 10 parts instead of 11.
Practical tip: always put the product in the bottle first, then top up with water. Lukewarm water often mixes better than cold. And mind your bottle size, because 200 ml of product plus 800 ml of water will not fit in a 750 ml bottle.
The confusion almost everyone has
This question has been popping up on detailing forums for years, and even experienced detailers struggled with it at first. The misunderstanding is almost always the same.
Many people read 1:4 as one part out of four total. That would make the product 25% of the mix. But in detailing 1:4 means one part product plus four parts water, so 1 in 5 total. Your product is then 20%, not 25%. A small difference in theory, but it explains why your mix keeps coming out a touch too strong or too weak.
So remember: the number after the colon is the number of parts of water, not the total. 1:4 is five parts together, 1:10 is eleven parts together. Always add the product on top.
Watch out: it differs per brand
The vast majority of brands, well over 95%, use the method above: 1 part product to X parts water. Think Koch Chemie, Chemical Guys and CarPro. Stick with that and you are right.
Only rarely does a brand count differently. The best-known example is Bilt Hamber, which does not put a 1:X ratio on the label but a percentage: 5% is 5 parts product in 100 total. That is the chemical method. Convert such a percentage to a ratio and 1:10 works out at 100 ml per litre instead of 91 ml. Does your brand work in percentages? Then set the calculator to Chemical.
And watch the order of the numbers. Some labels write it the other way around: 10:1 then means 10 parts water to 1 part product, something you mostly see on American brands. The bigger number is almost always the water. In the dilution calculator you pick Normal or Chemical at the top, so it always matches your brand. The label is always leading, and when in doubt, start more dilute rather than too strong.
Frequently asked questions
What does 1:10 mean exactly?
Why is 1:10 not 100 ml in a litre?
Do I add the product or the water to the bottle first?
What if I do not know which ratio to use?
About this guide
Written by T&H Car Care in Borne, the Netherlands. We specialise in car detailing and paintwork care in the Twente region. Browse our shop for the right cleaners and concentrates, or work out your dilution straight away with the dilution calculator.