Average Inventory

If your business makes or sells products, calculating its average inventory can help you gauge product performance over time. For instance, you could sell more umbrellas in a rainy April than in the sunny May that follows, but wish to calculate the average number of umbrellas in stock over that period of time to ensure you’re carrying the right amount of stock or spot discrepancies that could signal theft, breakage or spoilage.

How to Find Average Inventory

If you want to know the average inventory count over this two-month period of time, you would add the inventory count at the end of May to the inventory count at the end of April and divide the total by the number of data points (2).

Average Inventory = (#Products End of April + #Products End of May)/2

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A similar average inventory formula applies if you want to calculate the average inventory value over this two-month period:

Average Inventory = (April Inventory Value + May Inventory Value)/2 Months

This simple method finds the mean of inventory products or value over any time period. That time period could be a certain number of days, months, or years. A good rule of thumb is to compare apples to apples, choosing comparative time periods that are equal in value. Keep in mind that the months vary in number of days throughout the year.


Calculating over longer time periods tend to return more accurate numbers. For instance, if you compare inventory counts on Saturday and Sunday to Monday and Tuesday, website traffic to an e-commerce store could be much lower on the weekend and result in fewer sales. Extending the number of days or months included will give you a more accurate picture.

How Does Finding the Average Inventory Inform Business Decisions?

Whether you run your calculations on spreadsheets or a robust inventory software program like SOS Inventory, knowing the average number of products or sales your business conducts over a time period educates management about product performance.

A perpetual inventory system such as SOS Inventory allows businesses to update average inventory at any point in time based on the automatic updates to inventory counts that are ongoing. The sum is a moving average that accounts for market volatility. When every sale updates the physical inventory count, and numbers are updated regularly by every department in the business (every place a product is handled), figures are more reliable. Likewise, anyone in the company can generate a report about inventory counts, costs, sales, and profits at any point in time for thousands of products.  Having accurate information at your fingertips – no matter which area of the business you work in – supports better decision making and saves a lot of man hours.

Having the right tool to calculate average inventory ensures transparency, accuracy, and higher profitability. Why not get started with SOS Inventory today?


Thousands of companies use SOS Inventory to manage their businesses

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