What is Inventory Management?
Inventory management is the process of controlling and optimizing stock levels of raw materials, work-in-progress (WIP), and finished goods. The goal is to balance the cost of holding inventory against the risk of stockouts, ensuring products are available when customers need them.
Inventory management monitors stock levels, tracks product movement, sets reorder points, and uses models like Economic Order Quantity (EOQ) to minimize total cost—holding costs plus ordering costs.
Step-by-step worked examples
A bookstore sells 50 books daily. Each order costs $100 to place and receive. Holding one book costs $2/year. How many books should be ordered at once?
Using EOQ formula (simplified): EOQ ≈ √(2 × Annual Demand × Order Cost ÷ Holding Cost per unit) Annual demand: 50 × 365 = 18,250 books EOQ ≈ √(2 × 18,250 × 100 ÷ 2) ≈ √1,825,000 ≈ 1,352 books This minimizes total cost of ordering and holding.
A restaurant's soft drinks run out on Saturday nights. Current reorder point is too low. What should the restaurant do?
Analyze demand: peak demand on weekends vs. weekdays Set higher reorder point: trigger ordering at 200 units (vs. current 100) Increase safety stock: hold extra buffer for uncertain demand Monitor: track daily sales, adjust forecast and reorder point quarterly
A manufacturer faces long supplier lead times (30 days). How should inventory strategy change?
Lead time: need 30-day supply in stock at all times Reorder earlier: place order when 30 days' worth remains, not when stock is low Safety stock: increase buffer to cover supply delays Alternate suppliers: develop second source to reduce lead time risk
Flashcards
Quick quiz
Q1.Which cost(s) does inventory management aim to minimize?
Q2.If a product has high demand volatility, what should inventory management do?
Q3.A supplier's lead time is 60 days. When should you reorder?
Q4.What is the bullwhip effect in inventory?
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Common mistakes
Holding more inventory is always safer. — Correct: Excess inventory increases costs (storage, spoilage, obsolescence, capital) and reduces profitability.
Zero stockouts is always the goal. — Correct: Stockout prevention costs must be balanced against holding costs; some stockouts may be economically justified.
EOQ is the same for all products. — Correct: EOQ varies by product based on demand, order cost, and holding cost.
Just-in-time (JIT) means never holding inventory. — Correct: JIT minimizes inventory but still requires precise demand forecasting and reliable suppliers.
FAQ
What is the difference between inventory and stock?
Inventory = all materials (raw, WIP, finished goods) across the organization. Stock = finished goods ready for sale. Inventory is the broader term.
How does inventory management affect profitability?
Optimal inventory reduces carrying costs, prevents lost sales from stockouts, and frees up capital for other investments.
What is first-in-first-out (FIFO) inventory?
A method where the oldest stock is sold first, useful for perishables to minimize spoilage and obsolescence.
Why is inventory forecasting important?
Accurate forecasts prevent overstocking (wasted space and capital) and understocking (lost sales).