Does 'up to 50% off' pull people into a sale?

Probably, though nobody has actually shown it. The competition regulator's evidence review points to an Office of Fair Trading study that found "strong evidence that price framing", meaning the way a price is presented, "exerts a powerful effect". What nobody has tested is the "up to" headline itself. And a headline that exaggerates the sale can break the advertising code, and consumer law too if it's likely to change what shoppers decide, where the CMA says fines run to "10% of your turnover, or £300,000, whichever is greater".

Our interest, stated first. We run paid ads, and sale adverts are part of that work, so a big headline figure that pulls people in suits us. That doesn't make it safe to use one the range can't support.

This is part of our series on sale prices and urgency, checked. It reports what the evidence and the regulators say, with links to each source; it is not legal advice.

What the evidence says

That study is from 2010, and the examples of price framing the review gives are bundling, splitting a price into parts, and showing a higher reference price. None of them is an "up to" claim. We found no independent study of what an "up to" headline does for a small shop.

Can you use one legally?

It depends on your range. The advertising code says price claims such as "up to" and "from" "must not mislead by exaggerating the availability or amount of benefits likely to be obtained by the consumer".

The Chartered Trading Standards Institute's pricing guidance goes further: "You should only make such a claim if the maximum reduction quoted applies to a significant proportion of the range of products that are included in the promotion". It doesn't say what counts as a significant proportion, and one half-price item in a large range is unlikely to be enough.

The CMA's guidance also warns about small print. In its example, an advert says televisions are heavily discounted and a tiny footnote says only a few of them are. If shoppers wouldn't notice that footnote, and would have decided differently had they read it, "they will have been deceived by the overall presentation and misled".

What to do instead

• Count how many lines actually carry the top discount before you set the headline.
• If the top saving applies to only a few items, use a lower "up to" figure, or show the smallest saving alongside the largest.
• Put any conditions, such as a minimum spend, next to the figure rather than in a footnote.
• Every saving still needs a genuine usual price behind it, which our piece on using a 'was' price in a sale explains.

What to discount, and by how much, is a decision for a digital marketing strategy rather than for the advert.

The rest of the paid side is in how much Google Ads cost and why Google Ads aren't converting.