Onsite vs Offsite vs In-Store Retail Media: what each is, who sells it and how it is measured

Onsite is where retail media started and where most money still goes. The core format is the sponsored product: a paid listing that looks like a search result. Most onsite search ads are sold by auction on a cost-per-click (CPC) basis. That auction is now in court. The FTC alleges that Amazon told advertisers they paid one cent above the next bid. From 2019, it says, a hidden reserve meant Sponsored Products advertisers paid their full bid close to 80% of the time (TechCrunch, 31 August 2026). Amazon disputes the claim.

Onsite measurement is the most mature of the three. Walmart Connect's Sponsored Search click and impression metrics received MRC accreditation across desktop, mobile web and app (Walmart Connect, 16 October 2025). Self-serve tools are spreading outside the US too. Tesco Media launched Ad Manager on 9 October 2026, starting with Sponsored Products and adding display and video later (Grocery Trader, 9 October 2026).

Onsite also reaches people standing in the store. Jenny Holleran of Target's Roundel said its onsite ads reach the 60% of Target shoppers who use the app or mobile site while in the store (Adweek, 19 October 2026). That is why some retailers treat their app as their first in-store ad surface. Network detail is in the Amazon Ads, Walmart Connect and Tesco Media profiles.

Offsite sells the retailer's data, not its pages. A brand buys ads on a streaming service, a social platform or the open web, targeted at the retailer's shoppers, and gets sales reports back from the retailer. The data rarely leaves the retailer in raw form. Audiences are matched to the publisher's or demand-side platform (DSP)'s identifiers in a clean room, and only aggregated results return.

Four recent offsite examples show the range:

1. Walmart Connect ended its exclusive DSP deal with The Trade Desk in fall 2025 (Marketing Dive, 1 June 2026). On 28 May 2026 it announced a closed proof of concept that brings its audiences to VIZIO inventory through Yahoo DSP and Magnite (Walmart Connect, 28 May 2026). Walmart says offsite display delivered a median 52% new-to-brand customers in 2025 (company claim).
2. The Home Depot's Orange Apron Media lets advertisers launch Reddit campaigns from its self-service portal and is testing Pinterest for brands that do not sell at Home Depot (Marketing Dive, 23 April 2026).
3. Albertsons Media Collective supplies over 175 purchase-based audiences to YouTube buyers in Google's Display & Video 360, with SKU-level closed-loop reporting supported by LiveRamp (Marketing Dive, 27 April 2026).
4. Dollar General Media Network is moving onsite and offsite buying into The Trade Desk through an integration built with Kevel (Marketing Dive, 4 May 2026).

Amazon shows the opposite model: one owner, one platform. Its DSP was renamed DVA inside Amazon Ads Agent on 29 September 2026, and the automated DVA+ tier bills on CPM with no minimum spend (PPC Land, 29 October 2026). Data flows and clean room choices are explained in offsite retail media explained and clean room architectures compared.

In-store media is the oldest form of shopper marketing and the newest form of retail media. The difference is digital inventory that can be scheduled, priced and measured like other media. Retailers are adding that inventory quickly:

• CVS said in January 2026 it expected about 11,000 digital screens nationwide and checkout ads on point-of-sale systems in about 7,000 stores (Modern Retail, 11 September 2026).
• Walgreens began adding Looma screens to 1,200 stores in October 2026. Looma runs more than 7,000 screens across 10 retail banners (Modern Retail, 11 September 2026).
• Circle K reaches more than 6,600 US convenience stores and up to 200 million monthly impressions through pump media, store screens and checkout displays (company claim) (C-Store Dive, 20 August 2026).
• Sam's Club extended ads to fuel screens at more than 500 locations and added in-club radio (invidis, 24 April 2026).
• Albertsons serves about one million ads a day across 3,000 store screens, now run by Creative Realities (CRI figures) (invidis, 18 August 2026).

Not every in-store bet works. Instacart is closing its Caper smart-cart business, which carried targeted ads, and expects to finish by the end of Q2 2027 (Grocery Dive, 27 October 2026). Screens, audience measurement and programmatic buying are covered in depth in in-store retail media, and the CVS Media Exchange and Circle K Full Circle Media profiles show two models.

All three surfaces promise sales measurement, but the evidence differs. Onsite measurement is closed by design: the ad, the click and the purchase happen in one system. Closed-loop measurement works there without matching identities.

Offsite needs a match. The retailer must connect an exposure on another platform to a purchase in its own data. Clean rooms do that matching without handing over customer records, as in the Albertsons and YouTube setup. The open question is causality. Buyers increasingly ask for incrementality tests with a holdout group, not just attributed sales.

In-store is the hardest. The IAB/MRC guidelines say in-store impressions should follow the MRC's Digital Place-Based Audience Measurement Standards, counting people present in a screen's exposure zone (IAB/MRC guidelines, January 2024). IAB Europe's 2026 proposal goes further. It sets five store zones and an opportunity-to-see formula built from footfall, store count, duration, placements, aisle penetration and share of voice. It also aligns sales reporting to a 28-day window (ExchangeWire, 17 September 2026).

Retailers are adding sensors to fill the gap. Albertsons put beacon trackers on carts and baskets in an 80-store pilot to measure dwell time near displays, and planned to expand to about 800 stores (Grocery Dive, 6 February 2026). The best public evidence that store screens work comes from a Journal of Marketing field study of 237 campaigns and 30 million shoppers. It found point-of-sale signage raised the chance of buying a featured product by 8.1% (MarketScale, 2 November 2026). Standards for all three surfaces are compared in retail media measurement standards explained.

There is no published benchmark for the right split, so start from the job each surface does. Onsite captures shoppers who are already searching. Offsite finds people before they search, often on connected TV. In-store reaches the shopper who is already in the aisle.

Take a snack brand with an illustrative $200,000 for one retailer's quarter. It might fund search first, because onsite sales reporting is fastest. It could then test offsite with a holdout, so the retailer's report can show lift and not just matched sales. Finally it could buy one in-store flight in stores with screens near its shelf, where the Journal of Marketing study found the effect was strongest. The split is the brand's choice. The retail media economics calculator models the returns, and retail media trends 2027 shows where each surface is heading.

1. IAB and MRC, "Retail Media Measurement Guidelines" (January 2024). https://www.iab.com/wp-content/uploads/2024/01/IAB_Retail_Media_Measurement_Guidelines_January2024.pdf
2. IAB, "Final IAB/MRC Retail Media Measurement Guidelines Available for Download" (January 2024). https://www.iab.com/guidelines/final-iab-mrc-retail-media-measurement-guidelines-available-for-download/
3. PPC Land, "European retail media spending reaches €13.7 billion with 21.1% growth" (11 October 2025). https://ppc.land/european-retail-media-spending-reaches-eu13-7-billion-with-21-1-growth/
4. Marketing Dive, "Walmart Connect expands offsite advertising ambitions with Yahoo, Magnite" (1 June 2026). https://www.marketingdive.com/news/walmart-connect-expands-offsite-advertising-ambitions-with-yahoo-magnite/821575/
5. MarketScale, "Stores ring up most retail sales but earn 5% of retail media revenue" (2 November 2026). https://www.marketscale.com/industries/retail/stores-ring-up-most-retail-sales-but-earn-5-of-retail-media-revenue
6. The Desk, "WARC: Retail media ad market to top $200 billion as growth slows" (19 August 2026). https://thedesk.net/2026/08/warc-retail-media-ad-market-to-top-200-billion-as-growth-slows/
7. ExchangeWire, "IAB Europe Advances In-Store & Travel Media Measurement with New Proposals Open for Public Comment" (17 September 2026). https://www.exchangewire.com/blog/2026/09/17/iab-europe-advances-in-store-travel-media-measurement-with-new-proposals-open-for-public-comment/
8. TechCrunch, "FTC accuses Amazon of running a 'secret ad surcharge scheme' in new lawsuit" (31 August 2026). https://techcrunch.com/2026/08/31/ftc-accuses-amazon-of-running-a-secret-ad-surcharge-scheme-in-new-lawsuit/
9. Walmart Connect, "Walmart Connect's Sponsored Search earns MRC accreditation" (16 October 2025). https://www.walmartconnect.com/resources/articles/2025/walmart-connects-sponsored-search-earns-mrc-accreditation
10. Grocery Trader, "Tesco Media unveils new ad platform, shoppable formats and smarter in-store media" (9 October 2026). https://grocerytrader.co.uk/tesco-media-unveils-new-ad-platform-shoppable-formats-and-smarter-in-store-media/