What is Inventory Valuation?
Inventory valuation is the method you use to assign cost to products sold. When you have multiple shipments of the same product at different costs, you need a consistent method to calculate COGS.
Example: You buy USB cables in 3 shipments:
- Shipment 1: 500 units @ $2.00/unit = $1,000
- Shipment 2: 500 units @ $2.10/unit = $1,050
- Shipment 3: 500 units @ $2.20/unit = $1,100
- Total: 1,500 units in stock, $3,150 total cost
When you sell 600 units, which cost do you use? That's where FIFO and LIFO differ.
FIFO (First-In, First-Out)
What FIFO Means
Assume first items purchased are first items sold. You sell oldest inventory first.
FIFO Example
- Sell 600 USB cables
- First 500 units @ $2.00 (Shipment 1) = $1,000
- Next 100 units @ $2.10 (Shipment 2) = $210
- Total COGS: $1,210
- Ending inventory value: $3,150 - $1,210 = $1,940
FIFO Advantages
- Realistic flow: Matches how most businesses actually operate (old stock sells first)
- Higher profits: In inflationary times, lowers COGS and increases profit
- Better inventory valuation: Ending inventory valued at newer, higher costs (more accurate)
- Most common: Preferred by IRS and accountants
- Required for many businesses: US tax code requires FIFO for many inventory types
FIFO Disadvantages
- Higher taxes in inflation: Higher profit means higher tax bill
- Less cash in pocket: More taxes owed = less cash retained
LIFO (Last-In, First-Out)
What LIFO Means
Assume last items purchased are first items sold. You sell newest inventory first.
LIFO Example (Same Scenario)
- Sell 600 USB cables
- First 500 units @ $2.20 (Shipment 3, newest) = $1,100
- Next 100 units @ $2.10 (Shipment 2) = $210
- Total COGS: $1,310
- Ending inventory value: $3,150 - $1,310 = $1,840
LIFO Advantages
- Lower taxes in inflation: Higher COGS means lower profit, lower taxes
- More cash in pocket: Less taxes owed = more cash retained
- Tax savings compound: Especially powerful in high-inflation years
LIFO Disadvantages
- Unrealistic flow: Doesn't match how most businesses actually sell (last items first)
- Lower ending inventory value: Balance sheet shows outdated old costs (undervalues assets)
- Complexity: Harder to implement and track
- Restricted use: US allows LIFO, but many countries don't (IFRS prohibits it)
- LIFO reserves: IRS requires tracking LIFO reserve (additional complexity)
LIFO Limitations for Online Sellers
LIFO is rarely useful for Amazon/e-commerce sellers because:
- Inventory turnover is fast (sells in weeks/months, not years)
- Different platforms require different methods
- Most seller tools don't support LIFO
- Additional tax complexity rarely justified by savings
FIFO vs LIFO Comparison
| Aspect | FIFO | LIFO |
|---|---|---|
| COGS (USB example) | $1,210 (lower) | $1,310 (higher) |
| Gross Profit | Higher (higher profit) | Lower (lower profit) |
| Taxes | Higher tax bill | Lower tax bill |
| Inventory Value | Higher (modern costs) | Lower (old costs) |
| Realism | Matches actual flow | Unrealistic flow |
| Complexity | Simple | Complex (LIFO reserve) |
| Best For | Most online sellers | High-inflation, long-hold inventory |
Weighted Average Cost Method
Most online sellers actually use a third method: Weighted Average Cost
- Combine all inventory costs and divide by units
- Average cost per unit: $3,150 ÷ 1,500 = $2.10/unit
- Sell 600 units: 600 × $2.10 = $1,260 COGS
- Middle ground between FIFO and LIFO
Why Sellers Use Weighted Average
- Simple to implement in QB/Xero
- Reduces artificial profit/loss swings
- Acceptable to IRS
- Works well for fast-moving inventory
Which Method Should You Choose?
For most Amazon/Shopify sellers: Use Weighted Average or FIFO
Weighted Average is the default in most seller accounting software (Xero, QB). It provides a balanced, realistic approach that doesn't require complex tracking.
Decision Tree
- Fast-moving inventory (online sellers)? → Weighted Average (easiest)
- High-inflation environment? → LIFO (tax savings, but complex)
- Long-term inventory holding? → FIFO (most realistic)
- Conservative (match actual flow)? → FIFO (IRS preferred)
How to Set Up in QB/Xero
QuickBooks
- Go to Accounting → Chart of Accounts
- Select inventory items
- Choose FIFO or Average Cost in settings
- Apply to all items
- QB automatically calculates COGS on sales
Xero
- Go to Settings → General Settings
- Look for inventory settings
- Xero primarily uses Weighted Average
- Cannot switch to FIFO or LIFO in basic settings
Summary: Inventory Valuation Recommendation
Best for Most Sellers: Weighted Average Cost
Simple, realistic, tax-neutral, and built into most accounting software.
Alternative (Realism): FIFO
If you want to match actual inventory flow (oldest stock sells first).
Tax Optimization: LIFO
Only if high-inflation and long-hold inventory. Rarely worth complexity for sellers.