Standard Odoo Flow:

In Odoo Standard it is possible to select the following Costing Method : Average Cost (AVCO). This method allow to make a stock valuation in inventory. However this method is based on the units of the items entering and exiting the inventory. It is not based on the serial number level.

Customized Flow:

If a product is set as tracked 'By Unique Serial Number' and AVCO (Average Costing), this costing method will make the inventory valuation based on serial number.

Consider the following example::

Product A is tracked 'By Unique Serial Number' with AVCO costing method.

Input1 (by a Purchase) of 10 units of product A with a price of 10 €/unit, all serial numbers are identified.
Input2 (by a Purchase) of 5 units of product A with a price of 5 €/unit, all serial numbers are identified.

Output1 (by a sales) of 5 units of product A (the 5 serial numbers are the ones from input2 at a price of 5€/unit)


Difference in valuation:

Standard Odoo Flow:

Input (10 units * 10 € + 5 units * 5 €) / 15 = 8.33€/unit or stock valuation 125 €.
Output ( 5 units * 8.33 €) = 41.65 € or stock valuation of 83.35 €.


Customized Flow:

Input (10 units * 10 € + 5 units * 5 €) / 15 = 8.33€/unit or stock valuation 125 €.
Output ( 5 units * 5 €) = 25 € or stock valuation of 100 €.