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Why retail media measurement still ignores 70% of UK retail
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Retail media is one of the fastest-growing ad channels in the UK, with online retail media reaching £1.5bn in the first half of 2025 alone (IAB UK). Retailers like Ocado, Tesco, Morrisons and Iceland offer routes into grocery audiences, while Currys, John Lewis and Deliveroo represent entirely different shopping contexts spanning electronics, homeware, cosmetics and beyond.
Through retail media, these retailers give brands the ability to reach their shopper audiences with precise, contextually relevant messaging across a growing range of channels. Here is what it is, how a campaign works, and where to start if it is new to you.
Retail media advertising is paid media that uses a retailer's first-party shopper data to target consumers with relevant messaging. It works across two broad environments.
Epsilon Retail Media pairs CitrusAd’s onsite engine with cross-channel audience recognition and activation, so brands can move the same shopper from first impression to purchase. Find out more here.
Three things distinguish retail media from the digital advertising most brand teams are used to:
Retailers were not historically media owners. They have digitalised quickly, and many are now building media businesses at the same time as running them. The result is a landscape where every network looks and operates differently. There are now more than 200 retail media networks operating globally, with some estimates putting the figure closer to 270, and at least 28 active in the UK.
Consider the range. A business like Sainsbury's, with Argos sitting alongside its grocery operation, is a very different retail proposition to Iceland, or to a business like Wickes, which serves both trade and consumer audiences. Different customer bases, different data sets, different inventory, different commercial models. Each retailer is, quite rightly, building a media offering that reflects its own strengths and shoppers. But for brands and their agencies, who are used to buying media in more standardised ways, navigating that variation takes effort.
Fragmentation across platforms, teams, tools and measurement remains one of the biggest barriers to growth. According to IAB Europe, network fragmentation (51%) and lack of standardisation (53%) are the most significant challenges the industry faces.
The question is not simply who has the biggest reach, but whose data tells you the most about the people you want to find.
Those you sell through - The most straightforward starting point is a retailer you already sell through. You are reaching shoppers in a context where they can act on your message immediately. The data is rich, the path to purchase is short, and you can measure the full loop from impression to transaction.
Those you don't sell through - But the opportunity does not stop at the retailers that stock your products. Businesses in adjacent sectors like travel and quick service restaurants hold transaction data that can signal whether someone is in-market for what you offer.
Consider a platform like Deliveroo. If you are a drinks brand, a kitchen appliance company, or a meal kit provider, that kind of behavioural data could tell you who is in-market based on real spending patterns. This is where commerce media comes in. Commerce media takes the retail media model and expands it beyond traditional retailers, enabling any business with valuable transaction data to create media opportunities for aligned advertisers.
Whichever route you take, three things separate the networks that deliver real outcomes from the ones that simply promise impressions.
Identity underpins all three. Without a robust identity layer connecting real people across channels, touchpoints and transactions, reach is inflated, activation is fragmented, and measurement is incomplete. Solutions like Epsilon's COREid resolve online and offline signals to real individuals, and as IDC notes, "person-level identity is key to targeting, closed-loop attribution, data, and personalised scaled activation of ads."
For a deeper look at how to evaluate networks against these criteria, read the full guide.
Most retail media campaigns follow the same shape. The sequence mirrors the three pillars that underpin any successful retail media strategy: reach, activation and measurement.
Define your objective. Are you trying to drive sales, recruit new customers, or build awareness in a category? Pick one. It will shape everything else. Campaigns that try to do all three tend to do none of them well.
Build your audience. The default for many retail media networks is to target existing logged-in shoppers, which can mean you pay a premium to reach people already in your funnel. Identity-led targeting, built on deterministic data like name and address rather than just email, is what allows you to find genuinely new customers at scale.
Plan your activation. Onsite placements such as sponsored products, search ads and banners tend to drive conversion. Offsite placements across the open web, programmatic display, connected TV and audio tend to extend reach and build awareness. Most campaigns use a mix, and the strongest results come when these channels are planned together rather than activated in isolation.
Set your measurement framework. Before launch, settle which metrics matter, whether you will test for incrementality, and how in-store sales will be counted. The measurement plan should be designed to follow an impression through to a sale, both online and in store, and over a long enough window to capture higher-consideration purchases where weeks or months may separate first impression from final transaction.
Launch and optimise. Retail media data comes back quicker than most channels, and the brands that get the most from it treat the first few weeks as a live learning phase rather than a waiting period. Set objectives and efficiency guardrails up front, then let the data lead in-flight, shifting budget between placements and audiences based on real signals rather than assumptions made before launch.
When these steps fit together, the numbers can be serious. Currys ran a multi-channel campaign with Epsilon Retail Media that combined onsite retail media with connected TV and online video. It delivered a 46% conversion uplift versus display alone, 56,000 tracked in-store visits and a 3:1 return on ad spend, and went on to win Best Use of Retail Media at the Digiday Awards Europe.
If you want the longer version of how to think about reach, activation and measurement, the guide walks through each one and gives you the questions to ask any retail media partner before you commit.
