What are inventory valuation methods?
Inventory valuation methods decide which costs stay on your balance sheet as unsold stock and which costs move into expenses when you make a sale. The rule you pick changes reported profit, taxable income, and stock value even when the physical inventory is identical.
The methods exist because the same physical goods rarely cost the same over time. A unit you bought in January might cost more or less than an identical unit bought in March, so a business needs a consistent rule for which cost to expense and which cost to keep on the books.
That choice carries real money. IHL Group estimates the total cost of $1.7 trillion in inventory distortion, combining out-of-stocks and overstocks, reached that figure globally in 2026, equal to 6.2% of global retail sales. Accurate valuation will not fix distortion on its own, but it does decide how honestly that inventory shows up in your financials.
Key characteristics
- First in, first out (FIFO): The oldest costs move to cost of goods sold (COGS) first, so ending inventory is carried at the most recent costs.
- Last in, first out (LIFO): The newest costs move to COGS first. It is allowed under United States Generally Accepted Accounting Principles (GAAP) but banned under the International Financial Reporting Standards (IFRS); IFRS standard IAS 2 permits only FIFO and weighted average. Under the LIFO conformity rule, a business using LIFO for tax must also use it in reports to shareholders and creditors.
- Weighted average cost: All unit costs are blended into a single average cost per unit, which then applies to both COGS and ending inventory.
- Specific identification: The actual cost of each individual item is tracked, which works best for unique, high-value goods like vehicles or custom equipment.
- Consistent application: Every method feeds COGS and must be applied consistently period to period. To switch, the Internal Revenue Service (IRS) generally requires you to file Form 3115.
Example
Say you buy 100 units at $10 in January and 200 units at $12 in February, then sell 150 units.
Under FIFO, you expense the oldest costs first: (100 x $10) + (50 x $12) = $1,600 in COGS. Under weighted average, the average cost is $3,400 / 300 = about $11.33 per unit, so COGS is 150 x $11.33 = about $1,700.
Same goods sold, but $100 of difference in reported cost. That gap flows straight into profit and taxable income, driven only by the method you chose.
Related terms
- first in, first out (FIFO): The method that expenses your oldest inventory costs first.
- last in, first out (LIFO): The method that expenses your newest inventory costs first.
- weighted average cost method: The method that blends all unit costs into one average.
- cost of goods sold (COGS): The direct cost of the inventory a business has sold.
- inventory accounting strategies: Broader approaches for tracking and reporting inventory value.
FAQ
Which inventory valuation method is best?
There is no single best method; the right choice depends on your industry, whether your costs are rising or falling, and whether you report internationally.
Can I switch inventory valuation methods?
You cannot switch freely, because the IRS generally requires you to file Form 3115 to change your inventory accounting method.
Why is LIFO not allowed everywhere?
United States GAAP permits LIFO, but IFRS prohibits it, so businesses that report under international standards cannot use it.
Fishbowl supports FIFO, LIFO, weighted average, and specific identification, and syncs with QuickBooks and Xero to keep COGS accurate.