Blog · 21 September 2026
On-shelf out-of-stock rate: how to calculate it and what value to aim for?
In shortThe on-shelf out-of-stock rate is the share of references absent from the shelf at a given moment: number of references out of stock divided by the number of references that should be present, times one hundred. It is counted on the shelf, not in the inventory system. The French grocery average is between 5 and 8%; below 3% an aisle is very well run; above 10% it loses shoppers.
The definition that matters
The on-shelf out-of-stock rate (or on-shelf availability gap) measures what the shopper sees: the share of products that should be on the shelf and are not. It must not be confused with the stock-out rate, which measures what the inventory system sees (book quantity at zero). A product in the back room, or with wrong book stock, is out of stock on the shelf without being out of stock in the system. The gap between the two is exactly what inventory tools do not see.
The formula
On-shelf out-of-stock rate = (number of references absent from the shelf ÷ number of assortment references that should be present) × 100.
Example: an aisle of 600 references with 39 absent at the time of the count has an out-of-stock rate of 39 ÷ 600 × 100 = 6.5%.
Two details:
- count references (one product, one size), not units: a facing with a single unit left is not out of stock, an empty facing is;
- exclude references deliberately removed (end of line, seasonal out of season), otherwise the rate is distorted.
How to count
The rate is counted on the shelf, at fixed times, by someone walking the aisle with the assortment list. Three rules for the measure to be useful:
- Count at the same times every day, for example 11 am and 5 pm, to compare day to day.
- Count per aisle, never store-wide: a 6% store rate can hide 12% in fresh and 2% in household.
- Record the duration when possible: a reference absent at 11 am and at 5 pm was missing all day.
A manual count twice a day gives a snapshot. Continuous detection, by sensors, cameras or shopper reporting, gives a film: you see at what hour gaps appear and how long they last.
Benchmark values
| Situation | On-shelf out-of-stock rate |
|---|---|
| Worldwide average measured by Gruen, Corsten and Bharadwaj (2002) | 8.3% |
| French grocery stores, ECR France / IRI barometer | 5 to 8% depending on the banner |
| Very well run aisle | under 3% |
| Threshold above which shoppers change store for everyday products | over 10% |
Fresh, bakery and promotions are structurally above the store average; slow-moving aisles below. Comparing an aisle with its own value of the previous week is more useful than comparing it with the average.
Reading the rate per hour
The daily average hides the essential. An aisle counted at 9 am at 2% and at 6 pm at 11% does not have an ordering problem: it has a daytime replenishment problem. An aisle at 7% from opening has an ordering or book stock problem. This hourly reading tells you which lever to pull, as explained in how to reduce out-of-stocks on the shelf.
What shopper reporting changes
With ShelfAlert, every missing product reported by a shopper is dated and located: the dashboard gives the real out-of-stock rate per aisle and per hour without a counting walk, and the list of the products that are missing most often. 14-day trial, no payment card: see the plan for store managers.
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.
- Definition of the on-shelf out-of-stock rate: Définitions Marketing.