Comparing car care products by the price on the bottle is the most common mistake in the category, and it consistently points people towards the more expensive option.
The number that matters
What you actually spend is cost per use, not cost per bottle. For a ready-to-use product those are close. For a concentrate they are not remotely close, and the gap is large enough to change which product is genuinely cheaper.
How to work it out
- Take the bottle size in millilitres.
- Take the dilution ratio from the label — for example 1:20 means one part product to twenty parts water.
- Multiply the bottle size by the ratio to get the volume of working solution the bottle makes.
- Divide the price by that volume to get cost per litre of solution.
- Compare that figure between products.
A 500 ml bottle at 1:20 makes ten litres of working solution. At 1:400 it makes two hundred litres. The same bottle, the same shelf price, twenty times the output.
A worked example
Two shampoos, both 500 ml. One is ready to use at £4. One is a concentrate at £8 that dilutes 1:100.
- The ready-to-use bottle gives you 500 ml of solution. That is £8.00 per litre of solution.
- The concentrate gives you 50 litres of solution. That is £0.16 per litre of solution.
The concentrate costs twice as much on the shelf and roughly fifty times less per wash. Always check the actual ratio on the label of the product you are buying — ratios vary widely and the label is the only reliable source.
When ready-to-use is still the right answer
Concentrates are not automatically better. Ready-to-use makes sense when:
- You use the product rarely, and a large volume of concentrate would go out of date first.
- You want no measuring — for a quick job in a car park, a trigger bottle wins every time.
- Accuracy matters and you have no way to measure properly. Over-diluted product does not work; under-diluted can stain or damage.
- Storage space is genuinely limited.
Our BASIC range is deliberately ready to use for this reason, and the ADVANCED range is where the concentrates live.
Diluting properly
- Water into the bottle first, then product. It stops the solution foaming up and overflowing.
- Measure. Guessing wastes product when you go strong and wastes your time when you go weak.
- Mix only what you will use reasonably soon — diluted product does not keep as well as concentrate.
- Label the bottle with what it is and the ratio. You will not remember next month.
The honest summary
Concentrates are usually far cheaper per use, take up less space and produce less packaging waste. They ask for one thing in return: measure properly and follow the label. That is the entire trade-off.
Before you start
Always read the label on the product you are using and follow the instructions on it for dilution, application and safety. Work in the shade on cool paint, and test anything new on a small, hidden area first — particularly on trim, wraps and finishes you are not familiar with.
Not sure which product fits the job? SWAG Fast Lane asks three quick questions and puts the right kit together for you.