Weighted Average Inventory Cost Calculator
Weighted average inventory cost combines opening stock and purchases into one average cost per unit. The method is a common inventory-costing approach, subject to the accounting policy that applies to a business.
How to use this calculator
- Enter quantities and unit costs on the same cost basis.
- Check that all inputs use the same units, period and population scope.
- Change one assumption at a time when comparing scenarios.
Formula used by weighted average cost inventory calculator
Weighted average cost = (opening units × opening unit cost + purchased units × purchase unit cost) ÷ total units.
- Weighted average cost = (opening units × opening unit cost + purchased units × purchase unit cost) ÷ total units.
- The simple version covers only two cost pools and omits freight, discounts, returns, taxes and other capitalizable inventory costs.
- The tool validates inputs and rounds displayed figures for readability; it does not validate assumptions against external records.
Worked examples
Worked example
500 units at 8.50 are joined by 300 units at 9.25.
(500×8.50 + 300×9.25) ÷ 800 = 8.78125 per unit.
Weighted average cost is about 8.78125 per unit.
Understanding the result
Weighted average inventory cost combines opening stock and purchases into one average cost per unit. The method is a common inventory-costing approach, subject to the accounting policy that applies to a business.
The simple version covers only two cost pools and omits freight, discounts, returns, taxes and other capitalizable inventory costs.
Important notes
The simple version covers only two cost pools and omits freight, discounts, returns, taxes and other capitalizable inventory costs.
Treat the result as an estimate from the entered assumptions. For commercial, statistical, engineering or health-related decisions, verify relevant specifications and professional guidance.
Frequently asked questions
Does this calculate selling price?
No. It calculates weighted average inventory cost only.
Can it replace accounting records?
No. Apply your adopted inventory policy and accounting requirements.
How should I interpret this result?
The simple version covers only two cost pools and omits freight, discounts, returns, taxes and other capitalizable inventory costs.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.