IAB Europe draft cuts in-store ad impression formula to six inputs

IAB Europe on September 17, 2026 opened a revised set of in-store retail media measurement standards for public comment, proposing that retailers stop using the number of times an ad appears on a screen as the basis for counting audiences and start instead from the number of shoppers who come through the door. The Brussels-based trade body is taking feedback until October 23.

In Short

IAB Europe, the group that writes shared advertising rules for Europe, has published a draft that changes how shops count the people who might see ads on their in-store screens, starting from how many shoppers visit rather than how many times an ad is shown. This matters to brands paying for those screens, because retailers have been producing audience numbers in different ways and most shops have no way of knowing who actually looks at a screen. If the draft is adopted, retailers would use one shared calculation, disclose the guesses built into it, and report sales over four-week periods before and after a campaign.

A second version, two years on

The 27-page document carries the title "IAB Europe In-Store Retail Media Definitions and Measurement Standards - Version 2" and is marked as a draft for industry review. It revises a standard that IAB Europe and the Interactive Advertising Bureau in the United States wrote together. IAB Europe first put the joint in-store definitions out for comment on September 18, 2024, after a two-day workshop in July 2024 with 14 retail media networks, among them Ahold Delhaize, Douglas Marketing Solutions, Kingfisher, MediaMarkt and Schwarz Media. According to the new draft, Version 1 was finalised in December 2024 after a comment period that ran from September through November of that year. IAB US had separately published a playbook on digital out-of-home and in-store retail media in May 2024, and the two organisations aligned their work "to reduce market complexity and simplify buying across continents," according to the document.

What changed is that retailers tried to use the rules. Version 2 incorporates the outcomes of an In-Store Measurement Workshop held on July 1, 2026, "at which retailers reviewed how the Version 1 standards were being applied in practice," according to IAB Europe. The draft is candid about the result. "Applying the standards surfaced several nuances worth understanding," it states.

The in-store draft was one of two documents IAB Europe opened for comment on the same day. The other is a first draft of a Travel Media Measurement Addendum. Marie-Clare Puffett, IAB Europe's Senior Director Industry Development & Marketing, framed both as extensions of existing work. "Measurement has always been fundamental to trust in digital advertising, and that's just as important as Commerce Media expands into new areas such as in-store Retail Media and Travel Media," Puffett said, according to IAB Europe. "These proposals reflect months of close collaboration with retailers and travel media businesses and are designed to bring the same rigour and consistency to these fast-growing areas that the industry expects elsewhere."

IAB Europe describes the recommendations as "proposals rather than a final standard."

The ad play loses its place

The most consequential change sits in one short paragraph. Under Version 1 of the in-store standard, retail media networks were asked to report on ad play and gross impressions, with Opportunity To See (OTS) positioned as the future proxy for a viewable impression. Version 2 reverses the order. "Ad Play is not the right starting point for media measurement; footfall is," the draft states.

An in-store impression is now defined as visual contact with the ad, a definition the document says is consistent with how IDOOH in Germany and Route in the United Kingdom treat it. The impression becomes "the overarching trading currency," while OTS and Likelihood To See (LTS) describe how that impression is measured. Ad play and gross impressions survive only as supporting metrics that are still to be disclosed, "but neither is the trading currency on its own," according to the draft.

The hierarchy is set out in four rungs. Ad play counts the times an ad is displayed or rendered. Gross impression counts individuals present in a display's exposure zone while it is working, calculated as audience multiplied by ad play, and carries the caveat that the ad may have been shown when nobody was nearby. OTS counts the people who could pass an activation, or hear it in the case of in-store radio, and is described as "the best proxy available for a viewable ad impression in the in-store environment." LTS applies a further adjustment for the likelihood that someone noticed the content, and can only be reported by retailers with sensor or analytic technology. The document adds a one-line warning next to LTS: "This might have GDPR implications."

Web viewability rests on the same distinction, measuring whether an ad could have been seen rather than whether it was. The draft makes that link explicit, stating that viewable adjustments for digital place-based media are expected to conform to the requirement for digital video "in that it represents an opportunity to see, rather than confirmation that someone has seen the ad."

The shift puts IAB Europe at some distance from how store screens are already bought through automated channels. In digital out-of-home, impressions are generated from plays. IAB Australia's guide for programmatic buyers, published in August 2025, set out that programmatic DOOH is traded on impressions, with an impression multiplier determining audience reach per advertisement play. A standard that starts from footfall and a bid request that starts from a play are counting from different ends. The draft does not mention programmatic trading at all, so how a footfall-based OTS figure would translate into a per-play multiplier is left open.

The document also reaches back to the Media Rating Council. Its guidelines "have been used as the basis for the development of these standards," according to the draft, which asks retailers to follow the MRC's Digital Place-Based Audience Measurement Standards where applicable. According to the draft, inclusion in an audience estimate requires presence in the venue and the screen's exposure zone, dwell time and view, and screen traffic counts "can never be more than the venue traffic counts." The MRC has gone further in outdoor media. When it opened its Phase 2 out-of-home audience standards for comment on July 28, 2025, the draft listed evidence required for Likelihood to See, including asset size, obstruction, visual clutter, exposure time and speed and direction of travel. The in-store draft sets out no equivalent list; LTS is simply whatever sensor or analytic technology determines.

Six metrics and a 36 million example

The practical core of Version 2 is a shortened OTS calculation. According to the summary of changes, Version 1 carried an example built on eight variables. The new core uses six:

Multiplied together, the example produces 36,000,000 OTS for the campaign. The arithmetic runs in steps: 50,000 shoppers across 100 stores for 20 days gives 100 million store visits; three placements lift that to 300 million; 80% aisle penetration cuts it to 240 million; and a 15% share of voice leaves 36 million. That works out at 0.36 OTS per store visit.

Two features of the calculation are worth reading closely. The first is that it counts visits rather than people. Average daily footfall multiplied by the number of days counts a shopper who visits five times in a campaign five times. The second is that share of voice may enter twice. The placements variable, according to the draft, "should account for share of voice on the screen (if relevant)," yet a separate campaign share of voice is then applied as its own multiplier. The document does not say whether the two describe the same discount.

There is also a mismatch in how aisle penetration is labelled. The table heading calls it "% of shoppers that notice the media," while the definition beneath describes the share of shoppers "who will actively walk past the media location." Walking past and noticing are different claims; noticing is the territory the draft otherwise reserves for LTS and sensors.

Three of the Version 1 variables are kept as optional layers "for a higher level of fidelity": average touchpoint compliance, OTS per visit and a discount for awkward media locations such as floor stickers or hanging signs. Retailers applying them are asked to disclose which ones they used. They are not trivial. Applying the draft's own 80% touchpoint compliance example to the 36 million figure would reduce it to 28.8 million, a fifth lower.

According to the document, the Version 1 example calculation "was created with input from SMG and Scala/PRN." PRN is the in-store network that Perion agreed to buy for up to $12 million in cash, a deal disclosed on August 25, 2026, covering more than 750 warehouse club locations, more than 4,500 big-box stores and more than 2,200 healthcare stores. Perion's announcement did not state how PRN counts impressions or whether its networks report against the IAB standard. The simplified six-metric version, the draft notes, was agreed at the July 2026 workshop.

Four ways to guess who walked past

Aisle penetration, previously a single variable in the example, now gets its own sub-section setting out four methods, ranked from most to least precise:

1. Beacons in every store, at aisle level, giving direct visibility of shopper movement.
2. Beacons in a representative sample of stores, with the average extrapolated across the estate.
3. Category transaction inference, in which a purchase stands in for presence. The draft's example is a shopper who buys cereal from the "Cereal, Bread and Milk" aisle; "it is fair to assume they were exposed to any advertising within that aisle."
4. A one-off market study commissioned from a third party, providing category-level shopper behaviour.

Retailers are asked to disclose which method they used. The third method carries its own bias in two directions. It excludes shoppers who walk an aisle without buying from it, which pushes the figure down, and it assumes every buyer in a category was exposed to every ad in that aisle, which pushes it up. The draft does not attempt to quantify either effect.

Five zones, two kinds of measurement

The store zone map is carried over from 2024 without change: Zone 1 covers media outside the store, from car parks and fuel stations to window displays visible from the street; Zone 2 covers the entrance and out-of-category areas; Zone 3 the checkout; Zone 4 the aisles, including power aisles and gondola ends; and Zone 5 a catch-all for third-party services such as bank branches, coffee shops and optometrists, along with click-and-collect points, customer service and smart carts. IAB Europe's release describes a "five-zone framework" at the core of the proposals, but the zones themselves date from Version 1. What is new is guidance on how each zone is measured.

For Zone 1, established out-of-home conventions apply. In the United Kingdom retailers rely on Route, and in some markets, according to the draft, retailers can access GPS coordinates from mobile devices to report impressions. For Zones 2 to 5, measurement is "assumption-driven" unless sensors are deployed. The document puts the consequence plainly: "Without sensors, the assumptions behind the benchmark calculation (footfall, aisle penetration, touchpoint compliance) effectively are the measurement, which is why transparency on those assumptions is critical."

Disclosure requirements expand accordingly. Retailers are asked to state how footfall was gathered, whether through transaction data, panels or technology such as sensors, door counters and beacons, along with the assumptions used, the aisle penetration method and whether reported impressions are OTS or LTS. They are also asked to provide dwell time, in aggregate or as an average, with a distance matrix of viewability by zone. The diagram accompanying that requirement shows a camera's detection zone narrower than the screen's viewability zone, leaving a band marked "beyond detection" inside the area from which the screen can still be seen. Even a retailer with sensors, in other words, may not observe everyone who could see the ad.

Dwell time has become a selling point for vendors in the category. Grocery TV's 2026 shopper survey, which found 62% of 1,018 US grocery shoppers had bought a product after seeing it on an in-store screen, argued that pharmacy, deli counter and checkout zones perform because shoppers already wait there. The study was published by a company selling that inventory.

The standard's scope remains narrow. It covers digital screens, audio and connected shopping formats such as hand scanners, app-assisted shopping and smart carts. Printed and static formats and experiential activations such as product sampling "will be covered in future iterations." The appendix of format examples leans heavily on British grocery: seven of its 17 examples come from Tesco, with the rest from Boots, Co-op, Ahold Delhaize, Schwarz Media and Morrisons.

Grocery counts a purchase; electronics cannot

Version 1 listed footfall as a disclosure item. Version 2 gives it a sub-section and names the two ways of counting it: scanners at the door, or loyalty data when a purchase is made. The choice, according to the draft, depends on the category.

"In grocery, the starting point for footfall is often a transaction," the document states. "Tesco, for example, counts a purchase as an impression and de-duplicates where a shopper makes multiple store visits within the reporting window." In consumer electronics, that proxy breaks down, because shoppers visit to research without buying and transaction data lags the visit. Door scanners "therefore become more important in these categories."

The Tesco example also sits awkwardly beside the six-metric calculation. De-duplicated purchasers are closer to a reach figure than to the visit count the core calculation produces, and for an identical store estate the two could diverge widely. The draft asks for disclosure but does not reconcile them.

Sales windows shrink to 28 days

On the sales side, the recommended reporting frame moves from 30 days before and after exposure to 28 days, with retailers expected to offer flexible windows when brands ask. The document does not give a reason for the change. Twenty-eight days is four complete weeks, so the pre and post periods contain an identical number of each weekday, which a 30-day window does not guarantee.

IAB Europe's release lists a second change: "removing sales lift and brand sales lift metrics." Neither appears in the Version 2 draft. The remaining sales metrics are sales extrapolation, sales variance, brand variance, new to brand and new to category. Sales variance compares sales before, during and after a campaign and "should be used only when Incremental Sales studies are not possible," according to the draft. Brand variance relies on panels and surveys.

The documents do not describe the change in the same way. The summary-of-changes table inside the draft does not mention sales lift or brand sales lift. Instead, it records that a standalone incrementality sub-section has been removed and that incrementality "continues to be addressed under Incremental Sales/Brand Lift." No section with that name appears in the draft. The body ends with a one-line "Incrementality" heading that refers to a separate incrementality guide without naming it. IAB and IAB Europe published Guidelines for Incremental Measurement in Commerce Media on November 3, 2025. Whether brand lift survives in some form, and where, is not clear from the materials.

The removal of sales lift from the standard lands while vendors are selling exactly that. Grocery TV added third-party sales lift measurement from ABCS Insights to its in-store network in April 2026. Nine days earlier, In-Store Marketplace and Catalyst Media Consulting published research arguing that the obstacle to in-store scale is not missing technology but incompatible scorecards among brands, agencies, merchants and networks, proposing a Shopper Purchase Rate based on product movement rather than digital attribution.

Other sales definitions carry over. A new-to-brand shopper is one who bought nothing from the specified brands before the campaign and purchased during or after it, with three look-back tiers by purchase cycle: zero to six weeks for regularly bought items such as shampoo, bananas, nappies and milk; seven to 26 weeks for semi-regular purchases such as jeans, mascara and cartridges; and 27 weeks or more for infrequent purchases such as televisions, vacuum cleaners, winter coats and sofas. IAB will "aim to standardise product categories in the next version." Retailers extrapolating sales from identified shoppers, typically loyalty card holders, to unidentified ones are asked to disclose the metric through which extrapolation is done. The draft's example is an assumption that sales per impression are the same for both groups.

Loose ends in the draft

A few passages appear to have survived from Version 1 without being reconciled with the new definition. The OTS row in the impression table still states that "an ad may be displayed on a screen in an area of the store a customer didn't visit which would be considered an impression." That sits uneasily with an impression defined as visual contact, and with an aisle penetration factor designed to exclude shoppers who never pass the placement.

The table of contents lists an Acknowledgements section and an "About IAB and IAB Europe" section; neither appears in the draft. As a result, apart from SMG and Scala/PRN, the document does not name the retailers or measurement companies that took part in the July 2026 workshop.

Nor does the draft address audit. IAB Europe runs a certification programme for retail media networks, but its first certification, of Albert Heijn in September 2025, validated display and sponsored product formats across onsite properties. The in-store standard makes no reference to independent verification of footfall figures, aisle penetration studies or the assumptions it asks retailers to disclose.

The travel addendum

The companion document extends IAB Europe's Commerce Media Measurement Standards to travel. When IAB Europe opened Version 2 of those standards for comment in October 2025, it said they focused exclusively on online measurement and that future editions would cover travel and finance.

The travel draft itself was not among the materials reviewed for this article; its details come from IAB Europe's release. According to IAB Europe, the addendum was developed with Skyscanner, KAYAK, Expedia, Koddi, Booking.com and Sojern. It concludes that most existing standards apply to travel, while proposing seven-day attribution windows for sponsored products and 30 days for display and offsite advertising, a three-year look-back for new-to-advertiser metrics, and sales reporting standardised on gross bookings before cancellation. It aligns incrementality definitions with IAB Europe's existing guidelines and requires disclosure from organisations using sales extrapolation.

The two documents released on the same day use different time frames for different purposes. The in-store draft's 28 days is a pre-and-post sales reporting window. The travel draft's 30 days is an attribution window for display and offsite advertising.

Jason Wescott, Global Head of Commerce Solutions at WPP Media and chair of IAB Europe's Retail & Commerce Media Committee, described the proposals as "an important step towards greater clarity and transparency across both in-store Retail Media and Travel Media," according to IAB Europe.

Why the counting matters

In-store remains the least visible part of retail media spending. European retail media reached 13.7 billion euros in 2024, up 21.1%, with IAB Europe forecasting 20.8 billion euros for 2026. Yet IAB Europe's own AdEx Benchmark, published in July 2026, measured retail media on a basis that excludes in-store retail media altogether. When IAB Europe opened its commerce media standards for comment in 2025, it cited 70% of buyers naming a lack of standards as a barrier to investment.

What Version 2 offers is a common calculation and a list of things to disclose. What it does not offer is a way to observe the audience in most stores. For retailers without sensors, the draft concedes, the assumptions are the measurement. A brand comparing two retail media networks under the new standard would, in principle, be able to see each network's footfall source, aisle penetration method and compliance assumptions side by side. Whether two networks applying the same six metrics to similar stores produce comparable numbers depends on inputs the standard asks them to declare but not to verify.

Comments on both documents are open until October 23, 2026, according to IAB Europe.

Timeline

• May 2024: IAB US publishes a playbook on digital out-of-home and in-store retail media
• July 2024: IAB Europe holds a two-day workshop with 14 retail media networks to draft in-store standards
• September 18, 2024: IAB and IAB Europe open the first in-store retail media definitions and measurement standards for public comment, until November 1, 2024
• December 2024: Version 1 of the in-store standards is finalised
• March 26, 2025: IAB Europe publishes pan-European definitions separating on-site, off-site and in-store retail media
• July 28, 2025: The Media Rating Council opens its Phase 2 out-of-home audience standards, including Likelihood to See evidence requirements, for comment
• August 2025: IAB Australia publishes its programmatic DOOH buyer guide describing per-play impression multipliers
• September 2025: Albert Heijn becomes the first retail media network certified under IAB Europe's programme
• October 7, 2025: IAB Europe puts European retail media at 13.7 billion euros for 2024
• October 9, 2025: IAB Europe opens Commerce Media Measurement Standards V2 for comment, flagging future travel and finance editions
• November 3, 2025: IAB and IAB Europe publish Guidelines for Incremental Measurement in Commerce Media
• April 7, 2026: In-Store Marketplace and Catalyst Media Consulting argue that misaligned scorecards block in-store scale
• April 16, 2026: Grocery TV adds third-party sales lift measurement from ABCS Insights
• June 2, 2026: Grocery TV publishes a survey of 1,018 US grocery shoppers on in-store screens
• July 1, 2026: IAB Europe holds its In-Store Measurement Workshop, where the six-metric OTS calculation is agreed
• July 2026: IAB Europe's AdEx Benchmark measures retail media on a basis excluding in-store
• August 25, 2026: Perion agrees to buy in-store network PRN for up to $12 million
• September 17, 2026: IAB Europe opens Version 2 of the in-store standards and a first Travel Media Measurement Addendum for public comment
• October 23, 2026: Public comment period closes

Related PPC Land coverage

• IAB and IAB Europe release In-Store Retail Media measurement standards for public comment - The September 2024 Version 1 draft, with its store zones, formats and the retail media networks involved.
• IAB Europe releases updated retail media definitions for European markets - The March 2025 framework separating on-site, off-site and in-store retail media.
• In-store media's measurement problem is not what you think - Research arguing that four incompatible scorecards, not missing technology, hold back in-store advertising.
• Grocery TV adds third-party sales lift data to its in-store ad network - A vendor offering the sales lift measurement the Version 2 draft drops from the standard.
• Grocery TV study: 62% of shoppers buy after seeing an in-store ad - Vendor survey data on store zones and the dwell time argument for checkout and pharmacy screens.
• Perion acquires in-store ad network PRN for up to $12 million - The August 2026 purchase of a network named as a contributor to the Version 1 OTS calculation.
• IAB Australia releases comprehensive guide for programmatic DOOH buyers - How programmatic screens are traded on per-play impression multipliers.
• MRC opens public comment for out-of-home audience measurement standards phase 2 - The evidence the MRC proposed requiring before an outdoor exposure can count as Likelihood to See.
• IAB Europe opens public comment on commerce media standards - The online commerce media standards that the new travel addendum extends.
• IAB releases measurement framework for commerce media campaigns - The November 2025 incrementality guidelines and the scope of Albert Heijn's certification.
• Albert Heijn earns first retail media certification under new IAB Europe programme - The first audit under IAB Europe's retail media certification scheme.
• European retail media spending reaches €13.7 billion with 21.1% growth - IAB Europe's market sizing and forecasts through 2028.
• IAB Europe: retail media gains 16.7% as video passes half of EU display - The AdEx Benchmark and why its retail media figure leaves out in-store.
• IAB Europe retail media guide: what's actually holding retailers back - Measurement readiness and in-store infrastructure in IAB Europe's change management guidance.
• IAB Europe updates retail and commerce media landscape map - The vendor categories, including in-store ad tech providers, mapped by IAB Europe in October 2025.

Summary

Who: IAB Europe, the Brussels-based association for digital advertising, working with retailers, measurement providers and IAB US. The draft names SMG and Scala/PRN as contributors to the original calculation and Tesco as an example of grocery footfall counting. Marie-Clare Puffett of IAB Europe and Jason Wescott of WPP Media, chair of IAB Europe's Retail & Commerce Media Committee, are quoted in IAB Europe's release.

What: Version 2 of the In-Store Retail Media Definitions and Measurement Standards, a draft that defines the in-store impression as visual contact with an ad, makes footfall rather than ad play the starting point for measurement, replaces an eight-variable OTS example with a six-metric core calculation, sets out four methods for estimating aisle penetration, expands disclosure requirements and moves sales reporting windows from 30 to 28 days. IAB Europe's release also lists the removal of sales lift and brand sales lift metrics, which the draft's own summary table does not record. A separate first draft of a Travel Media Measurement Addendum was opened alongside it.

When: Opened for public comment on September 17, 2026, following an In-Store Measurement Workshop on July 1, 2026. Comments close on October 23, 2026. Version 1 was finalised in December 2024.

Where: The standards are pan-European and aligned with IAB US. The draft refers to Route in the United Kingdom and IDOOH in Germany for exterior media, and its format examples come mainly from UK and European grocers.

Why: Retailers applying Version 1 found that ad play did not reflect how many shoppers could see an ad, and that most stores lack sensors to measure it directly. Version 2 attempts to give retail media networks a common calculation and to make the assumptions behind each figure visible to buyers, while leaving verification of those assumptions outside the standard.