Inventory management is the practice of tracking, ordering, storing, and controlling the goods a business holds at every stage of the supply chain. The goal is to have exactly what you need, when you need it, without tying up unnecessary capital in excess stock or losing sales because shelves are empty. Every product a company sells has an optimal inventory level, and finding and maintaining that level is the central problem inventory management solves.
Done well, inventory management reduces carrying costs, minimizes waste, and keeps cash flowing. Done poorly, it results in stockouts that disappoint customers, overstock that drains cash, or spoilage that destroys margin.
First In, First Out (FIFO) assumes that the goods you received earliest are also the first goods you sell or use. This matches the physical reality of most inventory: the items you bought three months ago should leave before the items you received last week.
FIFO is the right choice for perishable goods like food, pharmaceuticals, and cosmetics because it minimizes the risk of expiration. It is also required under International Financial Reporting Standards (IFRS). During periods of rising prices, FIFO produces a lower cost of goods sold, which means higher reported profit and higher taxes.
Last In, First Out (LIFO) assumes that the most recently purchased inventory is the first to be sold. The cost assigned to each unit sold reflects current prices rather than older, usually lower prices.
During inflation, LIFO produces a higher cost of goods sold, which reduces taxable income. This is why US companies in industries like oil, metals, and chemicals have historically used LIFO for tax purposes. LIFO is permitted under US GAAP but prohibited under IFRS, making it unavailable to companies that report under international standards.
Just-in-Time (JIT) inventory management eliminates excess stock by ordering materials and receiving goods only when they are needed for production or sale. The warehouse is nearly empty by design.
Toyota pioneered JIT manufacturing as part of its production system starting in the 1970s. The approach slashes carrying costs and forces tight supplier relationships. The risk is fragility: any supply chain disruption, such as the semiconductor shortages of 2021 to 2023, exposes the vulnerability of businesses that hold no buffer inventory.
ABC analysis categorizes your entire inventory into three groups based on value and usage frequency. Category A items represent a small percentage of SKUs but the largest share of total inventory value. These get the tightest controls and most frequent review. Category B items are moderate in both count and value. Category C items are numerous but individually low-value, like fasteners and office supplies, and they get periodic review.
Think of it like prioritizing maintenance on your car: brakes and tires get checked before windshield wipers.
Economic Order Quantity (EOQ) is the formula-driven answer to how much you should order at once. It balances two competing costs: the cost of ordering frequently in small batches versus the cost of carrying large quantities of inventory. The EOQ minimizes the sum of both.
A business that orders too often pays more in transaction costs and administrative effort. A business that orders in very large batches pays more in warehouse space, insurance, and capital tied up in stock. EOQ finds the number that minimizes total cost.