Accounting & Reporting

Inventory Costing Methods

Same warehouse, same units, same money spent, and three legal ways to report wildly different profit. Learn which method does what, and why one of them is banned outside the United States.

  • Intermediate
  • 7 min total
  • 12 chapters

What decision this helps you make: Which cost-flow method to use, what it does to your reported margin and your tax bill, and how to read a competitor whose method differs from yours.

What this topic is

Inventory costing is the rule that decides which specific dollars leave the balance sheet as cost of sales when a unit is sold, and which stay behind as inventory. FIFO assumes the oldest costs go first, LIFO the newest, weighted average blends them, and specific identification tracks each item individually.

Why it matters

The choice does not change how much you spent or how many units you hold. It changes reported gross profit, reported inventory, and, in the United States, the actual cash you send to the tax authority. It also makes two otherwise identical companies look different, which matters whenever you compare, value, or buy one.

Who should learn it

Owners of any business that holds physical stock, finance staff who prepare or audit accounts, and anyone comparing companies whose inventory is a large part of the balance sheet.

What you will understand

  • What actually goes into the cost of a unit before any method is applied
  • FIFO, LIFO, weighted average and specific identification worked on the same numbers
  • Why LIFO exists, why IFRS bans it, and what the LIFO reserve tells you
  • Lower of cost and net realisable value, and the write-down rule that differs by regime

Prerequisites

Common misconception

"Inventory costing is about tracking which physical unit went out the door." It is not. FIFO does not mean you shipped the oldest box; it means you assumed the oldest COST left. The dollars and the widgets flow independently: a company can rotate stock strictly oldest-first and still report on LIFO, and nothing about that is dishonest.