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How to calculate beginning inventory?
Running a business

How to Calculate Beginning Inventory

By QuickBooks Australia
September 14, 20234 min read

Beginning inventory is a metric that helps you evaluate demand, check in on how you’re managing inventory, and plan for tax deductions. As such, being able to calculate beginning inventory and understand what this number means for the health of your business is essential.

Learn more about beginning inventory, how to use the beginning inventory formula, and what it means for your business’s finances in this post. If you’re still getting the hang of inventory management, we recommend taking the time to read through the entire guide.

What is Beginning Inventory?

Beginning inventory, or opening inventory, is the valuation of all inventory held by a business at the start of an accounting period. This value represents all the goods a business can put toward generating revenue. Beginning inventory is classified as a current asset and is an important aspect of inventory accounting.

Not sure how to calculate beginning inventory? We’ve got you covered. You can use the beginning inventory formula to better understand the value of inventory at the start of a new accounting period.

When Will You Use Beginning Inventory?

You’ll calculate beginning inventory, or your opening Inventory, at the start of an accounting period.

Being able to compare beginning inventory period-over-period can provide insights into business performance, such as inventory turnover and the value of your inventory. There are several reasons why knowing the value of beginning inventory can prove useful to your business, including:

  • Noting changes in demand: Any change to beginning inventory compared with the previous period usually signals a shift in your business. For instance, a lower beginning inventory count compared to the month prior could be a result of growing sales during the period. Higher beginning inventory could signal a downward trend in sales.
  • Identifying inventory management issues: A greater number of units leftover than usual could indicate a breakdown in your inventory management process if you didn’t reorder sufficient Inventory. If you have little-to-no beginning inventory, it could indicate that you possibly over-ordered inventory during the previous period.
  • Highlighting supply chain issues: Similarly, having more or less Inventory than usual could be due to an issue in the supply chain. The case may be that your supplier didn’t fulfill your order correctly, or you only received a portion of your inventory purchases.
  • Preparing to file your taxes: If you can Quote your average inventory at the end of an accounting period and how much you’ll need in the following period, you can pre-purchase inventory. Doing this can lower your taxable income that you account for on your income statements, which can help you reduce how much you owe.
  • Keeping an eye out for shrinkage: Shrinkage occurs when there’s a discrepancy between how much inventory should have been accounted for and what was actually accounted for. This is a problem for retailers and e-commerce wholesalers alike, and can occur due to human error, damaged products, or potentially stolen goods. While errors may happen occasionally, it’s important to keep an eye out for shrinkage patterns to ensure employees aren’t stealing merchandise.

Beginning inventory is a tool to help you better understand the sales and operational trends of your small business. With this data and the conclusions you can draw from it, you can make improvements to your inventory management strategy. With a better inventory method, you can also optimise the cost of inventory and improve gross profit.

How to Calculate Beginning Inventory

The beginning inventory formula is simple:

Beginning inventory = Cost of goods sold + Ending inventory – Purchases

Want to know how to find beginning inventory? Let’s break down the steps you need to know: 

1. Determine the cost of goods sold (COGS) using your previous period’s accounting records.

COGS = (Previous accounting period beginning inventory + previous accounting period purchases) – previous accounting period ending inventory

2. Multiply your ending inventory (sometimes called closing inventory) balance by the production cost of each inventory item. Do the same with the amount of new inventory.

Ending inventory = Previous accounting period beginning inventory + Net purchases for the month – COGS

3. Add the ending inventory and cost of goods sold. See the formula for calculating ending inventory above.

4. Subtract the amount of inventory purchased from the number above to calculate the value of beginning inventory.

If you’re going to use the beginning inventory formula to manually calculate this value, it’s important that you double-check your math. Using an incorrect number for beginning inventory can create a domino effect of miscalculations and mislead future decisions. To ensure accuracy, you may want to consider using a beginning inventory calculator.

Beginning inventory calculation example

To help you get more comfortable using the beginning inventory formula, here’s an example:

1. Determine the COGS using your previous accounting period’s records. Example: Candles cost $2 each to produce, and Jen’s Candles sold 600 candles during the year.

COGS = 600 x $2 = $1,200

2. Use your balance sheet to calculate your ending inventory balance and the amount of new inventory purchased or produced during the period. Example: Jen’s Candles had 800 candles in Inventoryat the end of the previous accounting period, and produced another 1,000 candles during the next year.

Ending inventory = 800 x $2 = $1,600

New inventory = 1,000 x $2 = $2,000

3. Add the ending inventory and cost of goods sold. Example: $1,600 + $1,200 = $2,800

4. To calculate beginning inventory, subtract the amount of inventory purchased from your result. Example: $2,800 – $2,000 = $800

Beginning Inventory Calculator

QuickBooks' Beginning Inventory Calculator allows you to calculate the value of all inventory held at the start of the accounting period. The calculator is a useful way to do proper record keeping for better financial management. 

To start your calculation, you must enter the following details: 

  • Cost of goods sold: Calculate this cash value by multiplying the cost of produced goods by the number of units sold in the preceding accounting period. Alternatively, you can use the QuickBooks COGS calculator to determine this value. 
  • Ending inventory: This includes the cash value of any stock left on the shelves at the end of the accounting period.
  • Purchases: This is the value of purchases added to the inventory during the previous accounting period. 

With just a few clicks, QuickBooks’ online calculator will perform computations in mere seconds. Try this simple online tool to make accurate calculations effortlessly. 

Take the Next Step Toward Better Inventory Management

Understanding how to calculate beginning inventory is an important aspect of improving inventory system management and the financial health of your business. But, that’s just the start. An inventory management software solution like QuickBooks can help you manage your multi-channel business much more efficiently.

With QuickBooks Online, you get access to features that allow you to track inventory, list and manage products, and fulfill orders all in one place. Plus, you’ll get access to reports that provide powerful insights above and beyond beginning inventory. Take control of your business and make smarter decisions that help you plan, sell, and grow.


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