What is a WSSI?
A WSSI (Weekly Sales, Stock & Intake) is a weekly retail plan that tracks the flow of stock through a season. Its core identity is closing stock = opening stock + intake − sales, and each week’s closing becomes the next week’s opening — so you always know your stock position and weeks of cover.
It is the standard in-season trading tool for merchandisers, especially in the UK and Europe.
The three lines
- Sales — what sells each week, against plan.
- Stock — opening and closing stock per week, and weeks of cover.
- Intake — receipts landing each week (tied to open-to-buy).
Read across the weeks and the WSSI shows where you will run short or pile up — early enough to adjust intake. For the operational walkthrough of that read on a worked grid, see how to read a WSSI, week by week.
The intake line is the same capacity that open-to-buy measures — the WSSI shows the weekly flow, OTB shows the remaining budget to buy. For how the two views fit together, see OTB vs. WSSI, or jump straight to the WSSI calculator.
What does WSSI stand for?
WSSI stands for Weekly Sales, Stock & Intake. It is a weekly retail planning view that tracks, for each week, what you sold, the stock you hold, and the intake (receipts) coming in — so you can see closing stock and weeks of cover at any point in the season.
What is the WSSI formula?
The core identity is: closing stock = opening stock + intake − sales. Each week’s closing stock becomes the next week’s opening stock. Weeks of cover = closing stock ÷ average weekly sales.
How is a WSSI different from open-to-buy?
They are two views of the same plan. A WSSI tracks the weekly flow of stock (sales, stock, intake); open-to-buy answers “how much more can I receive without exceeding plan.” The WSSI’s intake line and the OTB are directly related — the WSSI shows the flow, OTB shows the remaining budget to buy.
Who uses a WSSI?
Merchandisers and planners — especially in the UK and Europe, where the WSSI is the standard in-season trading tool. It is used to manage intake, spot stock-outs and overstocks early, and keep cover on plan.
Try it: the WSSI calculator projects closing stock and weeks of cover for a period; the open-to-buy calculator covers the intake-budget side. Or download the free WSSI template to build the full 13-week worksheet in Excel.
A spreadsheet WSSI works until you run it weekly across many lines and channels. RetailNorthstar keeps the WSSI live against plan as sales and intake land.