Inventory Turnover › Weeks of Supply
Weeks of Supply (WOS): Formula and Benchmarks 2026
WOS is the forward-looking planning metric. How many weeks would your current inventory cover at the forecast sales rate? Plan-level WOS is set per category, per week-of-season, and rolls daily on actual sell-through and inbound receipts.
Formula and DSI comparison
WOS = Current Inventory Units ÷ Forecast Weekly Sales
DSI = (Average Inventory $ / COGS) × 365
The key difference: WOS uses forecast demand, DSI uses historical COGS. WOS is for operating planning (next week, next four weeks). DSI is for financial reporting and external comparison.
Buyers and planners run WOS daily at the SKU level. CFOs and analysts run DSI quarterly at the company level.
Sector benchmark table
| Sector | Typical WOS | Note |
|---|---|---|
| Grocery (centre store) | 3-5 | Centre-store dry grocery only; perishables much shorter. |
| Apparel (specialty) | 10-14 | Plan WOS by week of season; ramps down post-peak. |
| Footwear | 12-18 | Size matrix forces deeper carry per style. |
| Electronics promotional | 4-8 | Promo windows; cut WOS hard at end-of-life. |
| Home improvement | 8-12 | Pro-customer mix shortens; DIY mix extends. |
| Toys (full year) | 12-20 | Pre-builds for Q4; depleted in November-December. |
| Furniture | 16-24 | Lead times and showroom inventory drive long WOS. |
Worked example: apparel buyer planning Q3 receipts
An apparel buyer is reviewing a denim style for fall.
- Forecast weekly sales = 250 units / week
- Plan WOS at season start (week 1) = 14 weeks
- Plan WOS by week 8 = 10 weeks
- Plan WOS by week 12 = 6 weeks
- Plan WOS at end of season (week 16) = 2 weeks
Translation to inventory units:
- Week 1 inventory target = 250 × 14 = 3,500 units
- Week 12 inventory target = 250 × 6 = 1,500 units
- End-of-season target = 250 × 2 = 500 units (to be cleared by markdown)
The buyer schedules inbound receipts and markdown cadence to walk inventory down this WOS curve. Variance from the WOS plan is the trigger for early-action decisions.