WSSI calculator
A WSSI — weekly sales, stock and intake — is the trading report that projects a department’s stock forward week by week, using the identity closing stock = opening stock + intake − sales − markdowns, with weeks of cover showing how long the remaining stock lasts at the current rate of sale. The calculator below runs the three-input form, with markdowns planned and tracked separately.
It is the weekly view UK and European planning teams trade against, and it is where an open-to-buy budget gets phased and monitored once the season starts. This calculator runs one period of that identity; the full method is in the three guides below.
Enter a period below to project closing stock and weeks of cover.
Building one, in six lines
A WSSI is a grid: weeks across the top, a small number of lines down the side, each line carried as plan, actual and the variance between them. Everything in it derives from three inputs — sales, intake and markdowns — plus the opening stock the season starts with, which is why it can be built in a spreadsheet for one department and why it becomes unmanageable across many.
- 01Opening stock (BOP). Carried straight from last week’s closing position, so it is only ever typed once. The first week of the season comes from the merchandise plan — or, after a count, from the counted figure rather than the book one.
- 02Sales. Planned and actual, at retail value and net of the reductions already taken. Plan is phased from the sales plan across the trading weeks; actual arrives weekly, and the variance between them is what everything downstream reacts to.
- 03Intake. Planned receipts by week, phased from the buy against real delivery dates, and actual receipts as they land. Intake is the only line a planner can still move in-season, and only inside the lead time — which is why a late intake week and an over-bought one look identical until you check the dates.
- 04Markdowns. The ticket value given up on stock still on hand at the moment the price changes. A full WSSI carries it as its own deduction, so the complete identity is closing = opening + intake − sales − markdowns; the calculator above runs the three-input form, which is the same arithmetic where markdowns are planned and tracked separately.
- 05Closing stock (EOP). Derived, never typed: opening plus intake, less sales and markdowns. It becomes next week’s opening, which means an error in any week propagates forward until someone reconciles against a real stock position.
- 06Weeks of cover. Closing stock divided by an average weekly sales rate. Divide by the trailing rate and it describes how long the stock would last at the pace just traded; divide by the forward forecast and it describes how long it lasts against what is expected. On a seasonal curve the two disagree, and the disagreement is the signal.
Read it every week in the same order — cover first, then the intake weeks that fix it, then the markdown the cover implies if intake cannot. Reading it in any other order produces a markdown decision before anyone has checked whether the stock was simply arriving late.
What is a WSSI? →
The definition, the lines, who owns it, and how it differs from a merchandise plan.
How to read a WSSI, week by week →
Cover, exception weeks, intake phasing, and the order to read the lines in.
OTB vs WSSI →
Open-to-buy sizes the budget; WSSI phases and monitors it. Where the two reconcile.
- 01Enter opening stock (BOP)The stock you hold at the start of the period.
- 02Enter intake and salesPlanned receipts into the period and planned sales over it.
- 03Enter weeks in the periodUsed to convert period sales into an average weekly rate.
- 04Read closing stock + coverClosing = opening + intake − sales. Weeks of cover = closing ÷ average weekly sales.
This WSSI calculator projects the weekly stock flow. To understand the method end to end, read what a WSSI is. The intake line ties straight to your buying budget — size it with the open-to-buy calculator, and see how the two views fit together in OTB vs. WSSI.
Running WSSI in Excel? See how RetailNorthstar keeps WSSI, OTB, intake, and buy plans connected.
Your calculator result is one number. RetailNorthstar keeps the whole plan connected — line plan, OTB, assortment, buy, POs, and production.
WSSI and OTB answer different questions. Open-to-buy sizes how much budget is left to commit over a period; WSSI phases that buy and tracks how sales, stock, and intake flow week by week, with weeks of cover showing how long the remaining stock lasts. Most teams need both — the WSSI is where the OTB plan gets monitored as the season actually trades.
A spreadsheet WSSI holds up for one department, but breaks at scale: copies drift out of version control, intake dates change and have to be re-keyed every week, and reconciling cover against the OTB budget across many lines and channels turns into manual cleanup. RetailNorthstar keeps sales, stock, intake, and OTB on one record, so the weekly position stays live where buying decisions are made.
Frequently asked questions
- What is WSSI?
- WSSI stands for Weekly Sales, Stock & Intake. It is a retail planning view that tracks how sales, stock, intake, and inventory cover move week by week, so a planner can see whether stock is building up or running thin against the rate of sale. Its core identity is closing stock = opening stock + intake − sales − markdowns, and a three-input form runs it where markdowns are planned and tracked separately.
- How is WSSI different from OTB?
- Open-to-buy (OTB) answers how much you can still commit to buy within a financial plan over a period. WSSI answers how sales, stock, and intake actually flow week to week, and how many weeks of cover the remaining stock represents. OTB sizes the budget; WSSI phases and monitors it. UK and European planning teams tend to rely heavily on WSSI as their primary trading view.
- What does a WSSI show you?
- A WSSI shows opening stock, planned and actual sales, planned and actual intake, and closing stock for each week, alongside weeks of cover. Read together, those lines tell you whether intake is arriving in time to support sales, where cover is too high or too low, and when a line is heading for a stock-out or an overstock that will need markdown.
- Can I run WSSI in Excel, and why does it get hard?
- Yes — for a single department a spreadsheet WSSI works fine. It gets hard at scale: multiple teams editing copies creates version-control problems, intake dates change and have to be updated by hand each week, and reconciling WSSI against the OTB budget across many lines and channels becomes error-prone. The weekly maintenance, not the maths, is what breaks down.
A real WSSI runs every week across many lines and channels. New to it? Read what a WSSI is and how to build one, download the free WSSI template, or pair it with the open-to-buy calculator.