How to Calculate the Cost of Goods

by K.A. Francis; Updated September 26, 2017
Calculating the cost of goods sold is not a complex calculation.

A key aspect of business accounting is cost of goods sold. This formula makes this calculation simple to understand: Beginning Inventory + Inventory Purchases - End Inventory = Cost of Goods Sold.

Calculate the business' beginning inventory. Determine the inventory amount at the beginning of the month. This amount is also the ending balance for the previous month. For example, the beginning balance of $500 for Feb. 1 is usually the same $500 ending balance for Jan. 31.

Total the amount of inventory purchased throughout the month. If your business bought $100, $200, $350 and $250 in consecutive weeks, the total inventory purchased for the month would be $900.

Add the beginning inventory to the amount of inventory purchased in the month. Using the $500 from Step 1 and the $900 from Step 2, the sum would be $1,400.

Determine the ending inventory balance for the month. The ending inventory is the value of the inventory left at the end of the month after all sales have been recorded. If you end the month with $350 in inventory, this would be your ending inventory balance.

Subtract the ending inventory from the sum of the beginning inventory and inventory purchased during the month. In the example, subtract the $350 ending inventory balance from the $1,400. The balance, $1,050, is the cost of goods sold.


  • Your beginning and ending inventory might not always match, depending on the inventory method used. For example, if you do not deduct inventory until it is received by the purchaser, and you make a sale on the last day of the month but the purchaser does not receive it until the first of the next month, the ending and beginning balances are going to differ by the amount of the last purchase.

About the Author

K.A. Francis is a freelance writer with over 20 years experience, and a small business consultant and jewelry designer. She holds a Bachelor of Arts in English and business administration and a Master of Arts in Adult Education. She has written for "The Einkwell," "Windsor Parent," MomsOnline, Writer's Stew, Lighthouse Venture Group and others. Her jewelry design company, KAF Creations, has been in operation since 1998.

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