WOC

WOC is a forward-looking supply chain measure that helps Amazon and vendors evaluate inventory health. It shows how long existing stock will last before replenishment is required, based on historic and forecasted demand.

How It Works:

• Formula:Example: If Amazon has 5,000 units of a product in stock and the weekly sales rate is 1,000 units, the WOC = 5 weeks.
• WOC can be calculated at different levels:
  • By ASIN
  • By category
  • By vendor portfolio

Benefits for Vendors:

• Inventory planning: Provides visibility into when replenishments are needed.
• Forecast alignment: Ensures production schedules meet Amazon’s demand cycles.
• Risk management: Helps avoid both stock-outs (low WOC) and overstock (high WOC).

Benefits for Amazon:

• Customer satisfaction: Maintains high instock levels and avoids delivery delays.
• Optimised supply chain: Balances FC capacity, storage costs, and replenishment cycles.
• Financial efficiency: Prevents excessive capital tied up in overstock.

Challenges:

• WOC depends on accurate demand forecasting - sudden spikes (Prime Day, seasonal demand) can quickly reduce actual cover.
• Low WOC increases risk of lost Buy Box and missed sales.
• High WOC creates overstock costs, ageing inventory, and possible markdowns.

Why It Matters:
For vendors, monitoring WOC is essential to maintain a healthy Amazon relationship. Amazon expects vendors to replenish before WOC drops below target thresholds, especially for high-velocity ASINs.

Example:
A vendor’s kitchen blender has 8 weeks of cover in June, but forecasted demand for July–August doubles due to seasonal promotions. Unless replenishment is shipped, WOC will drop to 4 weeks, triggering an instock risk.

In short:
WOC (Weeks of Cover) measures how many weeks of demand current inventory can meet, helping Amazon and vendors balance instock rates, replenishment planning, and inventory efficiency.