Inventory valuation (FIFO, LIFO, WAC): Definition, Formula & Why It Matters

Also called: FIFO, LIFO, Weighted average cost

Inventory valuation methods decide which costs are assigned to the items you sell. FIFO assumes the oldest stock sells first, LIFO the newest, and weighted average cost blends all purchases. The method changes your reported COGS, profit, and taxes.

Inventory valuation (FIFO, LIFO, WAC) formula

Weighted average cost = total cost of goods available ÷ total units available

Example

Buying two units at $100 and $120 gives a weighted average cost of $110 each.

Why it matters for Reverb sellers

Most resellers use FIFO or weighted average because they match how gear actually moves and are simpler to maintain. The method changes your COGS and therefore your margins, so it should be applied consistently.

How Verbstack helps

Verbstack tracks per-item cost so your COGS and margins stay accurate however you value inventory.

Track this on every order, automatically.

  • Real fees, margins, and profit on every Reverb sale
  • COGS and inventory tracked for you, no spreadsheet
  • Full history and a live monthly P&L
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