10 Common Mistakes to Avoid When Calculating Cost of Sales

Calculating the cost of sales (COS) accurately is crucial for understanding your business’s profitability and making informed financial decisions. However, many businesses make common mistakes that can lead to inaccurate calculations and financial mismanagement. Here are 10 common mistakes to avoid:

Including Indirect Costs

Mistake: Including overheads that are not directly related to production, such as administrative costs or sales and marketing expenses.

Solution: Focus on direct costs such as raw materials, direct labor, and manufacturing overhead.

Not Updating Inventory Values

Mistake: Failing to update inventory values can result in inaccurate COS figures and affect your gross profit calculation.

Solution: Regularly update inventory values to reflect current market prices and inventory levels.

Ignoring Discounts and Returns

Mistake: Not including discounts received on raw materials or returns from customers in the COS calculation.

Solution: Ensure that any discounts and returns are accurately recorded and included in the COS calculation.

Misclassifying Costs

Mistake: Incorrectly classifying costs as either direct or indirect, leading to an inaccurate COS.

Solution: Clearly define and classify costs to ensure they are correctly included in the COS calculation.

Using Incorrect Inventory Valuation Methods

Mistake: Using an inappropriate inventory valuation method (e.g., FIFO, LIFO, or weighted average) that does not accurately reflect the cost of goods sold.

Solution: Choose the inventory valuation method that best fits your business and consistently apply it.

Failing to Account for Work-in-Progress (WIP)

Mistake: Not including the cost of work-in-progress inventory in the COS calculation.

Solution: Ensure that WIP inventory is accurately valued and included in the COS calculation.

Not Considering Seasonal Fluctuations

Mistake: Ignoring seasonal variations in inventory levels and sales, which can lead to inaccurate COS figures.

Solution: Adjust inventory levels and COS calculations to account for seasonal fluctuations.

Overlooking Freight and Shipping Costs

Mistake: Not including the cost of delivering raw materials to your manufacturing facility or the cost of shipping finished goods to customers.

Solution: Include all relevant freight and shipping costs in the COS calculation.

Incorrectly Estimating Overhead Costs

Mistake: Using an inaccurate or outdated estimate for manufacturing overhead costs.

Solution: Regularly review and update overhead cost estimates to ensure they reflect current expenses.

Not Reconciling with Financial Statements

Mistake: Failing to reconcile the COS calculation with the financial statements, leading to discrepancies and potential errors.

Solution: Regularly reconcile the COS calculation with the financial statements to ensure accuracy and consistency.

By avoiding these common mistakes, you can ensure that your cost of sales calculation is accurate and reliable, providing a solid foundation for financial planning and decision-making.

Argentina Blue Dollar: A Guide for Global Business

Navigating Argentina's Blue Dollar rate in 2026? Don't let the official rate cut your payroll value. Learn how PhotonPay enables compliant, like-for-like USD payouts for global businesses.

PhotonPay

2026-01-19 07:20:31 · 5minute(s)

Best Ways to Send Money to Argentina in 2026

Stop losing money on exchange rates. Discover the best ways to send money to Argentina in 2026. Compare Western Union for individuals vs. PhotonPay for efficient, low-cost business payouts and mass payments.

PhotonPay

2026-01-19 06:58:38 · 5minute(s)

How to Scale Your Facebook Ads Securely Using Virtual Cards

Discover how to use Virtual Credit Cards (VCC) to scale Facebook ads securely. Learn to avoid account bans, manage ad spend, and optimize ROI with PhotonPay

PhotonPay

2026-01-09 08:37:18 · 5minute(s)