The short answer: before you sign off on a 20% Black Friday discount, ask how many of those customers would have bought anyway. A promotion only pays if it creates incremental demand: sales you wouldn’t otherwise have had. If most Black Friday buyers were already planning to buy, a discount simply gives away margin, and for premium brands it can teach customers to wait for the next sale.

Half of Black Friday shoppers are waiting for the discount

KPMG’s UK poll of 3,000 consumers, published in November 2026, found that 77% plan to shop during the Black Friday period or might be tempted to. Of that group, 49% said they had delayed buying items until then. Among Gen Z, the figure rose to 71%.

KPMG’s Linda Ellett read it as a sign that “at least some demand has been delayed” rather than lost, after weaker retail sales in late summer and October.

That’s good news for retailers expecting a busy November. But it gives premium brands a question worth asking before they set the offer: how much demand will the promotion create, and how much would have converted at full price?

If customers have already decided to buy and are simply waiting for the discount, the promotion isn’t creating growth. It’s moving sales you already owned into a cheaper week.

Marketers already suspect this

Les Binet and Dom Boyd’s research, presented at the IPA Effectiveness Conference in October 2026, suggests most marketers know this is happening but can’t prove it either way. In their survey of 250 senior marketing and insight leaders in UK consumer goods businesses:

  • 80% believe many promotional buyers would have bought at the higher price anyway
  • 75% can’t estimate what proportion of their promotions are profitable
  • 76% repeat promotions even when profitability hasn’t been assessed
  • 81% evaluate promotions over less than 13 weeks, too short to see what happens afterwards
  • 75% say repeated promotions increase price sensitivity

They also point to Nielsen’s analysis of 300 million price promotions, which found that nearly two-thirds lose money. Boyd’s separate analysis found that brands with the strongest pricing power achieve margins around 1.5 times higher than the weakest.

Binet and Boyd aren’t arguing against promotions altogether. Their warning is against using them to subsidise demand the brand already owns. (I covered the wider research in Black Friday promotions: when discounting helps growth and when it hides a problem.)

The maths of “would have bought anyway”

Here’s a simple example. Imagine a premium brand that would normally sell 1,000 orders in Black Friday week at £100 each, with a 60% gross margin. That’s £60,000 of gross profit.

Now run 20% off. Each sale earns £40 instead of £60, and orders rise 40% to 1,400. Revenue goes up from £100,000 to £112,000, and the campaign looks like a success.

But gross profit falls to £56,000. The 1,000 customers who would have bought anyway cost you £20,000 in discount. The 400 extra customers earn you £16,000. You’ve sold more and made less, before counting extra returns, delivery and the media needed to be heard in the busiest week of the year.

And it can get worse. If some of those 400 “new” customers were going to buy in December at full price, they weren’t extra at all. They were pulled forward.

The lesson isn’t that 20% off is always wrong. It’s that revenue uplift tells you very little. What matters is how many sales were genuinely incremental, and whether the profit from them outweighs the margin given away on everyone else.

Green Friday

When I was Head of Marketing at Frog Bikes, we chose Green Friday rather than a straight Black Friday sale. We took part in the moment with a sustainability message, a factory outlet offer and a giveaway with our partner Bikeability, rather than cutting prices across the range.

For a premium brand whose bikes held their value and were designed to be passed down, that mattered. Parents who were already planning to buy at full price weren’t given a reason to wait, and the brand still had something relevant to say in a week when every inbox is full of discounts.

Green Friday won’t fit every brand, and it shouldn’t be used as greenwashing. But the principle travels: give the promotion a job, and don’t spend margin on customers who were already yours.

How to measure whether a Black Friday discount worked

Most brands measure promotions on revenue during the sale. A better approach looks at three periods: before, during and after.

Before: set a baseline

  • Decide what “normal” looks like. Use the same weeks last year, adjusted for your growth trend, as the sales you’d expect without an offer.
  • Watch for the pre-sale dip. KPMG’s findings suggest many shoppers are holding off. If October and early November are soft, some of your Black Friday “uplift” is simply that demand returning.
  • Agree the success measure in advance. Gross profit, new customers and repeat purchase, not revenue.

During: build in a comparison

  • Use a holdout group. Send the offer to most of your email and CRM list, but hold back a random 10 to 20% who see full prices. Compare profit per customer between the two groups. It’s the simplest way for a small brand to see what the discount really added.
  • Separate new from existing customers. Use different codes or landing pages so you can see whether the promotion recruited anyone new, or mainly rewarded people who already buy from you.
  • Discount selectively. Test the offer on the products and channels that recruit new customers, and keep bestsellers your loyal customers already buy at full price.
  • Test advertising either side of the peak. If you want to know how incremental your paid media is, run lift or holdout tests in the weeks before or after Black Friday. During the peak itself, the noise makes results hard to read.

After: look three to six months ahead

  • Full-price sales in December and January. A sharp drop suggests you pulled sales forward.
  • Repeat purchase from Black Friday customers. Do they come back at full price, or only when there’s another offer?
  • Returns. Black Friday return rates are often higher, and they eat into profit long after the sale.
  • Price sensitivity. Are more customers asking for codes or waiting for sales?

For larger brands, econometrics (marketing mix modelling) can evaluate price, promotions and advertising on the same basis over time, which is what Binet and Boyd recommend. Smaller brands can get much of the way there with a holdout and separate codes for new and existing customers.

The question that matters most

Black Friday will be busy, and KPMG’s poll suggests plenty of shoppers are waiting for it. That’s exactly why premium brands need to be careful. The more customers who were already planning to buy, the more a sitewide discount costs you.

So before you sign off on 20% off, ask the question your sales report won’t: how many of these customers would have bought anyway?

This is the kind of question I help consumer brands answer as a fractional marketing director: looking at promotions, pricing and the wider marketing mix together, and building simple ways to measure what’s really working. If you’d like a second pair of eyes before this year’s peak, book a free 30-minute introductory call, or read what a marketing audit should cover.

Sources: Retail Times: KPMG UK, consumers holding back purchases for Black Friday promotions · Retail Week: Half of UK shoppers holding back spending until Black Friday · The Media Leader: Are you in a promotion dependency spiral? · IPA: Kicking the promotion habit · Marketing Week: Brands spend twice as much on price promotions as paid media · Frog Bikes example from the author’s own experience