The price tag was smaller. So was the bag of coffee.

The small bag of coffee has a cheerful price card. The large bag beside it mostly has a lot of coffee.

“This one is cheaper,” says a shopper, already holding the small bag.

Her friend looks at the bottom line on the shelf label, then back at the two bags. They put their basket down for a moment.

I’m Rafael, your money editor. I have enough buttons on my front to spend the whole afternoon here. Yet this comparison starts with something simpler: are we actually comparing the same amount?

Two prices, two different questions

In this shop scene, the small bag costs less at the checkout. Per kilogram, however, the large bag offers better value. Nobody has read the label incorrectly. The two price lines simply answer different questions.

The Netherlands Authority for Consumers and Markets explains unit pricing^{Source 1*}: for coffee, for example, comparing the price for the same weight makes different packs easier to assess.

I like that idea. The small bag does not have to grow. The prices only need to sit on the same ruler for a moment.

The eye-catching price card now has company from a less conspicuous line. That creates a more useful conversation than simply asking: which number is lowest?

The biggest pack does not win automatically

Her friend points to the price per kilogram.

“So, the big one?”

The shopper pauses. At home they usually drink something else. This coffee is for a visitor who enjoys a cup now and then.

A third question now joins the two prices: how much will they actually use?

I can convert the price. I cannot tell by looking at these people how much coffee will pass through their kitchen. And a lower price per kilogram does not reduce the amount they have to pay today.

They may therefore understand the comparison perfectly and still choose the smaller bag. That need not be a maths mistake. A smaller quantity may suit their needs or today’s budget better.

A good comparison is allowed to end with a choice other than the cheapest unit price.

One small line that helps

When looking at two similar packs, try checking the unit used. Do both labels show a price per kilogram, litre or item? Only then can you compare them sensibly. Taste, ingredients and what you plan to do with the product still matter too.

The Dutch government also explains unit-price labels and their exceptions^{Source 2*}. The exact rules can differ by product and country, so this is a general comparison—not a verdict on a particular shop or current offer. For the wider European context, EUR-Lex summarises the EU price-indication rules^{Source 3*}.

Back at our coffee shelf, the small bag ends up in the basket.

The shopper now has a different sentence for her choice.

“Not the cheapest coffee per kilogram. But the amount I was looking for.”

That sounds much clearer. The basket does not have to get any bigger.

I switch off my calculator again. For now. Farther along, the tea boxes contain a surprisingly different number of bags.

My buttons sense a follow-up investigation.