A concentrated detergent comes in 1 litre and a regular one in 3 litres: how do I compare them when the strength differs?
Do not compare per litre, because the tool does not know concentration, and a litre of concentrate does the work of more than a litre of regular. Instead compare on the number of washes or doses printed on each pack: enter it as the quantity with the piece unit, and the tool gives the cost per wash. That comparison is only as reliable as the information on the two packs.
Per litre: a misleading result
A 1 litre concentrate at 30 and a 3 litre regular detergent at 45. Per litre the tool says:
- Concentrate: 30 per litre, 100% more expensive.
- Regular: 15 per litre, the Best value.
The maths is right but the question is wrong. You are not buying litres; you are buying washes. And a litre of concentrate covers far more washes than a litre of regular.
Per wash: the real result
The back of the concentrate says 40 washes, and the regular one says 50 washes. Entered with the piece unit:
- Concentrate: 30 for 40 washes, so 0.75 a wash, the Best value.
- Regular: 45 for 50 washes, so 0.90 a wash, 20% more expensive.
The result has flipped completely: the detergent that looked twice the price is actually the cheaper one to use.
Steps
- Find the number of washes, doses or uses on each pack. It is often next to a washing machine symbol or in the dosing instructions.
- In the Unit-price comparison tool, enter the price, then the number of washes as the quantity, and pick piece.
- Do the same for the other pack, and make sure a wash means the same thing on both, such as a normal machine load.
- Read the cost per wash and the percentage gap.
Limits of this approach
- It relies on the manufacturer's figures. If you dose more than recommended, you get fewer real washes.
- If the two packs define a dose differently, such as a small load against a large one, the comparison is unfair.
- The tool does not measure how well anything cleans, only the cost per use.
The same idea works for concentrated shampoo, floor cleaners, tablets and anything used in doses. If one of the detergents is on offer, work out the price after the discount with the Discount calculator before entering it. And if you sell cleaning products, showing cost per wash on the product page can help customers see the value of a concentrate; work out your own price first with the Selling-price calculator.
Common questions
Why does the tool not ask me about concentration?
It compares price per unit of measure only and has no concentration field. Counting washes gets around that.
Is piece the right unit for a wash?
Yes. The piece unit means anything you count, whether an item, a wash or a dose.
What if the pack does not state the number of washes?
Use the recommended dose: divide the pack volume by the dose to get the number of uses, then enter that.