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.
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.
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.