Overstock is the less-discussed supply management problem — most attention goes to stockouts, but overstock costs money too: capital tied up in excess inventory, storage space consumed by supplies that won't be used for months, and eventual waste when supplies expire or become obsolete. An ordering system that prevents overstock orders the right quantity at the right time, every time. Here's how to build one.
The Overstock Root Cause
Overstock almost always comes from one of three causes: ordering based on estimates rather than actual usage data, ordering in larger quantities than needed to get a bulk discount, or ordering reactively after a stockout with an overcorrection. An ordering system that prevents overstock addresses all three causes with data, discipline, and defined quantities.
System Component #1: Usage-Based Reorder Quantities
Reorder quantities should be based on actual usage data, not estimates or round numbers. Calculate monthly usage for each supply category from your purchase history: (starting quantity + ordered quantity) − ending quantity = monthly usage. Set your reorder quantity to cover 6-8 weeks of usage — enough to avoid stockouts, not enough to create overstock. The labeled clear bins with threshold marks make current stock levels visible without counting, so reorder quantities can be calibrated precisely.
System Component #2: Maximum Stock Levels
Every supply category needs both a minimum (reorder threshold) and a maximum (overstock threshold). The maximum is the quantity above which you have more supply than you need for the next 8 weeks. When a reorder would bring stock above the maximum, reduce the reorder quantity. Mark the maximum level on every bin alongside the reorder threshold — two marks, two clear boundaries, no guesswork about whether an order is appropriate.
System Component #3: Centralized Ordering with One Approver
Overstock accumulates when multiple people can order supplies independently without visibility into what others have ordered. Centralize all supply ordering through one approver who checks current stock levels before placing any order. All reorder requests go through the approver; the approver verifies stock is below the reorder threshold before ordering. One approver, one view of total stock, no duplicate orders.
System Component #4: Quarterly Overstock Audit
Even a well-designed ordering system accumulates overstock over time as usage patterns change. Quarterly, audit every supply category: identify any supply where current stock exceeds 8 weeks of usage at the current usage rate. Reduce the reorder quantity for overstocked categories and skip the next reorder cycle if stock is significantly above the maximum. The quarterly audit catches overstock before it becomes a storage problem.