What is the Weighted Average Method?

Weighted Average Method

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Weighted Average Method

The Weighted Average Method is an accounting technique used for assigning the average cost of production to a product or service. It’s commonly applied in inventory valuation and cost flow assumptions in various industries. The main principle behind this method is to calculate a single average cost per unit that is applied uniformly to all units, regardless of their individual production costs.

The method is particularly useful when individual items are not distinct from one another, making it difficult or impractical to track individual costs. In such cases, the weighted average method helps in simplifying the accounting process by aggregating costs over a specific period and averaging them out.


The weighted average cost per unit is calculated as follows:

\(\text{Weighted Average Cost per Unit} = \frac{\text{Total Cost of Inventory}}{\text{Total Units in Inventory}} \)

Example of the Weighted Average Method

Let’s assume a fictional grocery store has a series of apple purchases and wants to determine the cost of its apple inventory using the Weighted Average Method.

Inventory Transactions

  • Beginning inventory: 200 apples at $0.50 each (Total Cost: $100)
  • First Purchase: 300 apples at $0.60 each (Total Cost: $180)
  • Second Purchase: 500 apples at $0.55 each (Total Cost: $275)

Steps to Calculate the Weighted Average Cost per Apple

Step 1: Calculate the Total Cost of Inventory

Total Cost of Inventory = $100 (Beginning inventory) + $180 (First Purchase) + $275 (Second Purchase)

Total Cost of Inventory = $555

Step 2: Calculate the Total Units in Inventory

Total Units in Inventory = 200 (Beginning inventory) + 300 (First Purchase) + 500 (Second Purchase)

Total Units in Inventory = 1000

Step 3: Calculate the Weighted Average Cost per Unit (Apple in this case)

\(\text{Weighted Average Cost per Unit} = \frac{\text{Total Cost of Inventory}}{\text{Total Units in Inventory}} \)

Weighted Average Cost per Unit = $555 / 1000 = $0.555 $


So, using the weighted average method, each apple in the inventory would be valued at $0.555. This cost will be used for the valuation of the remaining inventory and for calculating the cost of goods sold if some of the apples are sold.

The Weighted Average Method is a commonly used approach for inventory valuation and provides a way to allocate costs uniformly to individual items, especially when those items are largely identical.

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