Accounting

Weighted Average Cost

Inventory valuation using average cost of all units in stock

Definition

The Weighted Average Cost method is an inventory valuation technique that calculates the average cost per unit by dividing the total cost of all goods available for sale by the total number of units available. Every time a new purchase is made, the average cost per unit is recalculated. This method is permitted under Indian Accounting Standards (Ind AS) and is popular among Indian businesses because of its simplicity. Unlike FIFO, it does not require tracking individual batches, making it easier to implement in small businesses with high-volume, low-value items. The weighted average method smooths out price fluctuations over time, providing a more stable cost figure for goods sold. It is especially useful for businesses that deal in fungible goods like grains, chemicals, or hardware items where individual units are indistinguishable from one another.

How It Works

  1. 1Every time you purchase new stock, the system recalculates the average cost per unit by dividing the total cost of all available units by the total quantity.
  2. 2When you sell items, the cost of goods sold (COGS) is calculated using this average cost, not the cost of any specific batch.
  3. 3This method smooths out price fluctuations — if one batch was bought at ₹40 and another at ₹50, the cost assigned is ₹46 (the weighted average), not either extreme.
  4. 4The remaining inventory is also valued at this average cost, giving you a stable and easy-to-understand stock valuation for financial reporting.

Example

You own a stationery shop. On 1st June, you buy 200 notebooks at Rs. 40 each (total Rs. 8,000). On 15th June, you buy another 300 notebooks at Rs. 50 each (total Rs. 15,000). Your weighted average cost = (Rs. 8,000 + Rs. 15,000) / (200 + 300) = Rs. 23,000 / 500 = Rs. 46 per notebook. If you sell 150 notebooks, your COGS = 150 x Rs. 46 = Rs. 6,900, and remaining stock value = 350 x Rs. 46 = Rs. 16,100.

How Stock Register Handles This

  • Enable weighted average valuation in settings and the app auto-recalculates cost per unit with every new purchase entry
  • View real-time average cost for every item on the stock overview screen without manual calculations
  • Generate COGS reports using weighted average cost for accurate profit calculations and pricing decisions
  • Switch between valuation methods (FIFO vs Weighted Average) and compare the impact on your profit margins

Formula

Weighted Average Cost = Total Cost of Inventory / Total Units in Stock

Example: If you bought 200 units at ₹40 each (₹8,000) and 300 units at ₹50 each (₹15,000), then Weighted Average Cost = (₹8,000 + ₹15,000) / (200 + 300) = ₹23,000 / 500 = ₹46 per unit.

Related Terms

FIFO (First In First Out)LIFO (Last In First Out)Stock Valuation

Related Guides

Stock Valuation Guide

Frequently Asked Questions

When is weighted average better than FIFO?

Weighted average is simpler and works best for fungible items like grains, chemicals, hardware, or stationery where individual units are interchangeable. FIFO is better for perishable goods or items with batch-specific expiry dates where you need to track which batch was sold first.

Does the average cost change with every purchase?

Yes, the weighted average cost is recalculated every time you make a new purchase at a different price. For example, if your current average is ₹46 and you buy a new batch at ₹55, the new average will increase to somewhere between ₹46 and ₹55 depending on the quantities.

Can I use weighted average for GST and income tax purposes?

Yes, the weighted average method is accepted under Indian Accounting Standards (Ind AS 2) and is valid for both GST and income tax purposes. However, once you choose a method, you must apply it consistently across financial years.

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