Weeks of supply estimates how long current inventory will last at a specified weekly sales rate.
How it works in retail
A simple calculation divides available units by average or forecast weekly unit sales. Forward-looking versions use future demand rather than a historical average.
A retail example
A shop holds 150 units of an item and expects to sell 30 per week. On that assumption, it has five weeks of supply.
What to keep in mind
The estimate changes with seasonality, promotions, returns and stock receipts. Zero or unstable sales make a simple ratio less useful.
Examples are illustrative. Terminology and measurement conventions can vary by business and market.