What is weeks of supply in retail?

Weeks of supply (WOS) is units on hand divided by average weekly units sold. It tells you how many weeks the current stock would last at the current selling pace. A store with 400 units on hand selling 50 units a week has 8 weeks of supply — enough for an 8-week runway, not more.

What is the weeks of supply formula?

Weeks of supply = units on hand ÷ average weekly units sold. Use a trailing average (last 2-4 weeks) for a read on current pace, or a planned weekly rate for a forward-looking projection into the rest of the season. Guard against dividing by zero when weekly sales are still zero early in a launch.

How do you calculate weeks of supply for a markdown decision?

Calculate weeks of supply, then compare it with the weeks remaining before your season exit date. If weeks of supply exceeds weeks remaining, the current price will not clear the stock in time and a markdown should move earlier. If weeks of supply is comfortably under weeks remaining, price can hold or even firm up.

What does WOS mean in retail buying and planning?

WOS stands for weeks of supply, a velocity metric planners and buyers use alongside sell-through and turnover to judge whether inventory is moving fast enough for its remaining selling window. It is the same idea as days of inventory, just expressed in weeks, which matches how most retail calendars and markdown schedules are built.

How is weeks of supply different from inventory turnover?

Turnover measures units or dollars sold over a period relative to average inventory, giving an annualized or seasonal rate. Weeks of supply is the inverse idea applied at a point in time: how long the current stock lasts at the current pace. Turnover judges a season after the fact; weeks of supply is a forward-looking, week-by-week trigger.

Should weeks of supply use trailing sales or planned sales?

Use trailing sales (the last 1-4 weeks) to see where you actually stand today. Use planned sales — the rate your markdown schedule assumes for the coming price period — to project forward and test whether that plan will actually clear the stock. The two should be compared, not treated as interchangeable.

What weeks of supply number should trigger a price change?

There is no universal number; it depends on your weeks remaining in the selling window. The trigger is relative: weeks of supply greater than weeks left means the plan is behind and price needs to move. Track the gap, not just the raw WOS figure, since a WOS of 10 is fine with 12 weeks left and a problem with 4.

Weeks of supply calculator

Weeks of supply (WOS) = units on hand ÷ average weekly units sold. It is the single number that turns a sell-through rate into a runway: how many weeks the current stock lasts at the current pace, compared with how many weeks you actually have left before the season ends.

Build the full markdown schedule Sell-through rate calculator

Weeks of supply formula and worked example

Weeks of supply = units on hand ÷ average weekly units sold. If a style has 500 units on hand and is selling 50 units a week, weeks of supply is 500 ÷ 50 = 10 weeks. That number only means something next to the weeks actually remaining in the selling window.

If 10 weeks are left in the season, that style is exactly on pace — the stock and the calendar run out together. If only 6 weeks are left, weeks of supply (10) exceeds weeks remaining (6): the current price will not clear the stock, and a markdown should move earlier rather than wait for a worse read next week.

Weeks of supply calculator

Units on hand

Average weekly units sold

Weeks left in season

Target ending units

Weeks of supply: 11.1 wks
Units projected to sell: 450
Projected ending units: 50
Gap vs target ending stock: +0 units
Verdict: Behind pace

Use a trailing 2-4 week average for a current-pace read, or your planned weekly rate for a forward-looking projection into the next price period.

Forward-looking WOS: trailing sales vs planned sales

Trailing weeks of supply uses recent actual sales and answers "where do we stand today." Forward-looking weeks of supply substitutes the planned weekly rate for the next price period — the rate your markdown schedule assumes — and answers "will this plan actually clear the stock." Run both: a gap between them means the plan is assuming a lift that hasn't shown up yet.

Weeks of supply against a fixed 10-week runway (500 units on hand)

Units on hand	Units / week	Weeks of supply	Weeks left	Read
500	50	10.0 wks	10 wks	On pace
500	35	14.3 wks	10 wks	Behind — pull the break forward
500	20	25.0 wks	10 wks	Badly behind — break now and deeper
500	80	6.3 wks	10 wks	Ahead — delay or soften the break
500	0	∞	10 wks	Stalled — investigate before pricing

Related velocity metrics

Weeks of supply vs days of inventory vs turnover

All three describe the same underlying pace, at different time scales and directions.

Weeks of supply

Units on hand ÷ weekly units sold

Forward-looking runway in weeks. Best matched to a markdown calendar, since price periods are usually planned in weeks.

Days of inventory

Units on hand ÷ average daily units sold

The same idea expressed in days instead of weeks — multiply weeks of supply by 7 to convert between them.

Inventory turnover

Units or $ sold ÷ average inventory, over a season or year

A backward-looking rate for a full period, not a point-in-time runway. High turnover and a high current weeks of supply can coexist if pace just slowed.

Keep planning

Sell-through rate calculator
The weekly percentage that feeds directly into the weeks-of-supply denominator.
Inventory turnover calculator
The backward-looking counterpart to a point-in-time weeks-of-supply read.
When to mark down inventory
Turning a weeks-of-supply gap into an actual markdown decision date.
Open-to-buy calculator
Weeks of supply that's too low is a buying signal, not a markdown signal.

Answers

Weeks of supply questions

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