FIFO Inventory Method Explained for Ecommerce

What Is the FIFO Inventory Method?

FIFO stands for First In, First Out. It is an inventory valuation method where the oldest stock in your warehouse is assumed to be sold first. When you calculate cost of goods sold (COGS), FIFO uses the cost of your earliest purchased inventory before moving to newer, potentially more expensive batches.

For ecommerce sellers, FIFO is the most commonly used method because it aligns with how most businesses actually move physical products — you ship the oldest items first to prevent spoilage, obsolescence, or damage from prolonged storage.

How FIFO Works in Practice

A Simple Example

Imagine you sell phone cases and made three purchases:

• January: 100 units at $5 each = $500

• February: 100 units at $6 each = $600

• March: 100 units at $7 each = $700

In Q1, you sell 150 units. Under FIFO, your COGS is calculated using the oldest inventory first:

• 100 units from January at $5 = $500

• 50 units from February at $6 = $300

• Total COGS = $800

Your remaining inventory is valued at 50 units at $6 ($300) plus 100 units at $7 ($700) = $1,000.

Compared to LIFO

Under LIFO (Last In, First Out), the same 150 units sold would use the newest costs first:

• 100 units from March at $7 = $700

• 50 units from February at $6 = $300

• Total COGS = $1,000

FIFO results in lower COGS and higher reported profit when costs are rising, while LIFO does the opposite. This distinction matters significantly for taxes.

Why FIFO Is Preferred for Ecommerce

Tax Implications

Under FIFO during periods of rising costs (which is most of the time with inflation), your COGS is lower, which means higher taxable income. While this sounds like a disadvantage, it also means your balance sheet reflects a higher, more accurate inventory valuation, which matters for financing, acquisition discussions, and investor reporting.

Important: LIFO is not permitted under IFRS (International Financial Reporting Standards), which means businesses operating internationally are essentially required to use FIFO or weighted average.

Cash Flow Accuracy

FIFO gives you a more realistic picture of your actual costs because the remaining inventory on your books is valued at the most recent (and usually most accurate) prices. This prevents your balance sheet from showing outdated, artificially low inventory values.

Physical Inventory Alignment

Most ecommerce businesses physically ship older inventory first, especially for perishable goods, seasonal products, and items with shelf lives. FIFO aligns your accounting with your actual warehouse operations, simplifying reconciliation.

Implementing FIFO in Your Business

Inventory Management Software

Modern platforms handle FIFO automatically:

• Shopify — uses FIFO by default for inventory cost tracking

• ShipBob — 3PL that applies FIFO at the warehouse level

• Cin7 and TradeGecko — full inventory management with FIFO costing

Warehouse Organization

If you manage your own fulfillment, organize your warehouse to support FIFO:

1. Place new inventory behind existing stock on shelves
2. Label batches with received dates
3. Train pickers to always pull from the front (oldest stock)
4. Conduct monthly spot checks to ensure compliance

Accounting Integration

Ensure your bookkeeper or accountant uses FIFO when preparing financial statements. If you use QuickBooks, Xero, or similar software, set the inventory costing method to FIFO during initial setup. Changing methods later requires IRS approval in the US.

When FIFO Might Not Be the Best Choice

FIFO is ideal for most ecommerce businesses, but consider alternatives if:

• Costs are falling — in rare deflationary environments, LIFO produces lower COGS and less tax

• You sell commodities — weighted average cost may be simpler and equally accurate

• You have specific identification needs — high-value items like jewelry or art should use specific identification, tracking the actual cost of each individual unit

For 90% of ecommerce sellers shipping consumer goods, FIFO is the right choice. It is simple, widely accepted, and keeps your books aligned with reality.