Black Friday Planning for UK Retailers: What to Do in September, Not November
The ONS data shows Black Friday moves demand rather than creating it. Here is how to decide whether to discount at all, and the campaign work that has to happen twelve weeks out.
Black Friday falls on 27 November this year. If you are a UK retailer and your plan for it is currently "we will put something together in November", you have already given up most of the advantage, because the decisions that determine whether the week works — stock, margin, audience size, site capacity — all have lead times measured in weeks.
Black Friday planning for UK retailers is mostly a September and October job. What happens in the last week of November is execution, and by then your options have narrowed to changing bids and hoping.
Black Friday moves demand, it does not create it
This is the part most planning decks skip. Look at what the ONS actually recorded for the last full Black Friday period: non-seasonally adjusted retail sales volumes rose by 11.9% over the month to November 2025, against a 4.4% rise in October. An enormous month, on the face of it.
Then look at the seasonally adjusted figure from the same release. Volumes fell by 0.1% over the month, which the ONS described as a slightly weaker Black Friday effect than usual. The same bulletin notes that around 3 in 10 adults said they planned to shop the sales, with 19% intending to shop less than the previous year against 10% intending to shop more.
Both numbers are true. The raw spike is real, and so is the fact that once you account for the season, November was not an unusually strong month. What that means commercially is straightforward: for most retailers Black Friday pulls December revenue forward and applies a discount to it. That is sometimes worth doing. It is not automatically worth doing, and treating it as a growth event rather than a timing event is how businesses end up with a record week and a worse quarter.
Decide now whether you are discounting at all
The question to settle in September is not how deep to go. It is whether to participate.
Discounting works when you have margin headroom, when the products are substitutable, and when a first purchase reliably leads to a second. It works badly when your positioning depends on not being discounted. A luxury menswear brand like Hilditch & Key is not competing on price in November, and running 30% off would cost more in brand equity than it returned in volume. Plenty of smaller premium brands discount anyway, because everyone else is, and then spend January explaining to themselves why full-price sell-through collapsed.
If you are not discounting, say so early and loudly. "No Black Friday sale, same fair price all year" is a position, and it converts. Silence just looks like you forgot.
Tell Smart Bidding what is coming
If you are discounting, your bidding needs warning. A sitewide 25% off will lift your conversion rate sharply and immediately, and Smart Bidding will be learning that on the fly while the money is being spent.
Google's seasonality adjustments exist for exactly this: you schedule an expected conversion rate change and campaigns bid into it rather than discovering it late. Two caveats from Google's own documentation, both of which get ignored. They are built for short events of one to seven days and work poorly stretched past fourteen, so a month-long "Black Friday season" is the wrong shape for the tool. And they are only worth using when you expect a major conversion rate change, because Smart Bidding already handles ordinary seasonality — applying an adjustment to a modest promotion tends to make things worse, not better.
Set the adjustment to the change you genuinely expect, not the change you hope for. If your last sale lifted conversion rate by 40%, use that, not 100%.
Get the feed and the audiences right in September
Two jobs that cannot be done at the last minute.
The first is your product data. Merchant Center disapprovals, missing GTINs and price mismatches between feed and site take days to resolve, and a disapproval on 26 November is a disaster in a way it never is in June. Fix the feed while it is boring — our guide to Google Shopping feed optimisation covers what actually moves the needle, and the same work carries your Google Ads performance for the rest of the year.
The second is audience size. Remarketing and Customer Match lists take time to fill, and the cheapest Black Friday revenue comes from people who already know you. Running traffic campaigns in October to build lists you spend against in November is a far better use of budget than bidding into a crowded auction cold. There is more on which audiences justify the spend in our piece on retargeting strategy, and it applies equally to paid social, where audience quality dominates everything else in Q4.
The site is the constraint, not the budget
Every year, the failure point for UK retailers is the same and it is not media. It is a checkout that falls over under load, a delivery cut-off that is not stated on the product page, a discount code field that is invisible on mobile, or a page that takes six seconds to render when traffic triples.
You cannot fix any of that on the day. Load test in October. Put your Christmas delivery cut-off dates on the product page, not just in a banner. Make the offer legible in the first screen. This is conversion work, and in a week when traffic is guaranteed and expensive, a percentage point of conversion rate is worth more than a percentage point of anything else.
Measure it against the quarter, not the week
Judge Black Friday on Q4 as a whole. The week will look good almost regardless — that is what a discount does. The questions worth answering afterwards are whether December held up, whether the customers you acquired came back, and whether your blended margin across the quarter improved or you simply sold the same goods for less.
Set that up before you start, because you cannot reconstruct it in January.
Thomas has run this planning cycle with retail and ecommerce clients for years, and writes about it on LinkedIn. If you want a second opinion on whether Black Friday is worth it for your business this year, or you want the campaign structure built properly before the auction gets expensive, get in touch.
