FIFO (First In, First Out)

First In, First Out (FIFO) is an inventory accounting and physical handling method in which the oldest stock is sold or used first. The first units received become the first units shipped, and the most recent receipts remain in inventory until earlier batches clear.

What FIFO means

FIFO operates on two levels:

• Physical FIFO: warehouses physically rotate stock so older units ship before newer units. Critical for perishables, dated goods (cosmetics, supplements, food), and trend-sensitive inventory.
• Accounting FIFO: when calculating COGS, the cost of the earliest units is matched against the most recent sales. If unit costs have risen over time, FIFO assigns lower historical costs to COGS, making reported gross margin higher.

Why FIFO matters for ecommerce

FIFO is the default inventory method for most Shopify brands and the only method permitted in many jurisdictions for accounting purposes (notably under IFRS, which prohibits LIFO). Beyond the accounting, the operational case is direct: products with expiry dates, formulation revisions, or seasonal relevance lose value when held too long. FIFO ensures the oldest, most at-risk stock is the first to leave inventory.

FIFO in 3PL and warehouse operations

FIFO requires either physical organization (oldest pallets at the front, newest at the back) or system-enforced lot tracking. Most modern 3PLs support lot-level FIFO tracking through their warehouse management systems. Brands selling perishables or dated goods should specifically confirm FIFO handling and lot tracking when evaluating 3PL partners — it's not always a default, and the cost of getting it wrong is dated stock the brand can't legally sell.

FIFO vs. LIFO vs. weighted average

• FIFO: oldest cost matched to revenue first. Tends to report higher gross margin in periods of rising costs.
• LIFO: newest cost matched to revenue first. Tends to report lower gross margin (and lower taxable income) in periods of rising costs. Permitted under U.S. GAAP, prohibited under IFRS.
• Weighted average: all unit costs are blended into a single average. Smooths the impact of cost volatility and is simpler to administer.

FIFO trade-offs

• In rising-cost environments, FIFO inflates reported margins relative to LIFO — looks better on financial statements but creates higher taxable income.
• Physical FIFO requires warehouse discipline; without it, lot tracking errors or expired goods become real costs.
• FIFO assumes orderly receipt and dispatch — works well for stable SKUs, less well for products with frequent reformulation or version changes.