Blog · 21 September 2026
What does a shopper do in front of an empty shelf?
In shortAccording to the largest study on the subject (71,000 shoppers in 29 countries), in front of an empty shelf 31% of shoppers buy the product in another store, 26% take another brand, 19% another size of the same brand, 15% delay the purchase and 9% give up. The store loses the sale more than once in two, and is almost never told: the shopper does not say so, they leave.
The five reactions, measured
The study by Gruen, Corsten and Bharadwaj for the Grocery Manufacturers of America remains the reference: 71,000 shoppers surveyed in front of real out-of-stocks, in 29 countries. Their reactions:
| Reaction | Share of shoppers | Sale for the store |
|---|---|---|
| Buys the product in another store | 31% | lost |
| Takes another brand | 26% | kept |
| Takes another size of the same brand | 19% | kept |
| Delays the purchase | 15% | uncertain |
| Buys nothing | 9% | lost |
Added up, the reactions that lose the sale for the store (another store, abandonment, and part of the delays) exceed half of the cases. And in the most frequent case, the shopper went to a competitor.
What changes with the product
The reaction depends on the product more than on the shopper:
- High brand loyalty products (coffee, cosmetics, baby food, pet food): the shopper does not substitute, they go elsewhere or wait. The out-of-stock costs the whole sale.
- Everyday low-attachment products (toilet paper, sugar, oil): the shopper substitutes readily, the store keeps the sale but not always the margin.
- Promoted products: the shopper came for this product at this price; an out-of-stock on a promotion is the most irritating and the one that makes people change store the most.
- Products of a complete basket (the ingredients of a meal): a single out-of-stock can make the whole basket be abandoned.
The effect that is not seen straight away
An isolated out-of-stock is forgiven. A repeated out-of-stock on the products a shopper buys every week changes their default store. The ECR France / IRI barometers estimate at 45 the number of baskets lost per day and per hypermarket to out-of-stocks: that is the immediate cost. The deferred cost, the loss of regular shoppers, is measured nowhere, because the shopper who left does not explain why.
Why the store does not find out
A shopper in front of an empty shelf has three options: look for an employee, ask at the desk, or leave. Most leave. Those who ask often get “we’re out of it” without the information reaching the manager. Result: the store discovers the out-of-stock at the next walk, or never if the book stock says the product is there.
The only person who sees every out-of-stock at the moment it happens is the shopper. Giving them a way to report it in two seconds, without an account or an app, turns those 31% who leave into useful information. That is the principle of ShelfAlert: a QR code in the aisle, the shopper scans the missing product, the manager receives the alert and sees the most-requested products. See the plan for store managers, 14-day trial, no payment card.
Sources
- Gruen, Corsten, Bharadwaj, “Retail Out-of-Stocks: A Worldwide Examination of Extent, Causes and Consumer Responses”, GMA, 2002: full study (PDF).
- ECR France / IRI out-of-stock barometer: LSA, out-of-stock rate.