How to Calculate Shopify COGS When Prices Keep Changing

Cost of Goods Sold (COGS) sits at the top of your P&L statement and is central to  understanding your store’s profitability. 

Sell a product for $50, buy it for $20, and make $30. That works well for stores with consistent product costs. But anyone running a Shopify store knows it’s rarely that simple. Supplier prices vary , additional costs appear, and not every expense fits neatly into Shopify’s default cost fields. Over time, these small gaps can distort the real profit behind each sale and your overall profitability.

In this article, we will walk through how you can calculate COGS in shopify , where common reporting gaps occur, and how merchants can track COGS more accurately.

Why is Calculating COGS Important? 

COGS lays the foundation for profit calculations. It helps determine your Gross Profit, the first and most important margin in your P&L.

Here’s how it connects:

Gross Profit = Revenue − COGS
Gross Margin = (Revenue − COGS) ÷ Revenue

Gross profit is the starting point for calculating other margins. If your COGS is inaccurate, every margin you calculate after that will also be unreliable - from contribution margins (after fulfillment and marketing costs) to net profit (after all operating expenses). 

This is why calculating accurate COGS is so important. It helps you:

• Understand the true profit behind each product you sell

• Track margin changes as supplier and production costs increase

• Get accuracy in gross margin and net profit reporting

What is Included in the COGS Calculation?

What costs make up COGS? Let’s first get the basics right before we learn how to calculate COGS accurately. 

COGS includes all the direct costs involved in producing or acquiring the products you sell.

• Raw materials: The basic materials used to produce your products

• Direct Labor costs: Wages or salaries paid to employees directly involved in the production or assembly of the product.

• Packaging costs: The materials used to package your products before they are sold or shipped.

• Manufacturing overhead: For merchants who manufacture their products, this includes certain production-related overhead costs such as rent, utilities, equipment maintenance, and production supplies.

• Import duties or customs fees: Taxes or duties paid when importing inventory from international suppliers.

• Freight or shipping costs to receive inventory: The cost of transporting inventory from your supplier or manufacturer to your warehouse or fulfillment location.

Fluctuations in any of these costs and other factors will impact your COGS, which causes it to change over time.  

How To Add Cost Of Goods Sold In Shopify

Shopify provides a Cost per item field within each product or variant. 

To add a cost in Shopify, go to the product page in your admin, find the Cost per item field, and enter the cost associated with that product.

When a sale occurs, Shopify multiplies this cost by the number of units sold to calculate the Cost of Goods Sold (COGS) for that order. This value is then used in Shopify COGS reports and profit calculations.

For example, if the cost per item is $20 and you sell 5 units, Shopify records $100 as COGS for that sale.

This method provides a simple way for merchants to track costs and estimate their gross profit within Shopify.

However, the method works best only when:

• Product costs remain constant

• Inventory is purchased at the same price every time

The truth is, many merchants experience cost changes over time and Shopify’s default cost tracking becomes harder to rely on. 

Let’s look at where the gaps occur in Shopify’s COGS reporting.

Major Limitations with Shopify COGS Reports

Single Static Cost Problem

Shopify lets you add the COGS of products and variants, but it only allows for a single cost per product or variant. This rigid setup makes it impossible to track changes in costs over time or  account for vendor pricing differences, which is a major pain point, especially when you've got existing stock at one price and a new batch comes in at a different price.

Breaks Historical Report Accuracy

COGS in Shopify works by appending new data to the cost field and reflecting that value in past reports as well. This means that if a product first costs $10 and you sell 50 units, Shopify records $500 as COGS. If the cost is later updated to $15 (due to vendor pricing differences), reports will reflect the new value. This can break report accuracy when you're trying to analyze past performance. 

In the next section, we will cover how Bloom can solve these COGS issues for accurate profit tracking. 

Shopify Cogs App: For Accurate Cost and Profit

Bloom automatically pulls in product costs from Shopify. But, if you are tracking COGS externally or if you need more flexibility when assigning costs per product or variant, you can manage and define those costs directly in Bloom. 

This makes it possible to:

COGS by Date and Quantity Breaks

Bloom allows you to assign COGS by date and quantity breaks, which makes it easier to reflect cost changes as sales happen. If costs change over time, you can define the period during which a specific cost applies using start and end dates. If costs fluctuate based on the number of units purchased or sold, you can set quantity ranges to apply the correct cost to those units.

Plus, you can even create multiple sets of ranges for both dates and quantities to capture different cost scenarios, keeping your COGS reporting accurate.

Automated COGS and Profit Tracking 

You can manually enter costs based on the rules that apply to your business. Once a cost change is recorded, the update appears in reports within a few hours and is automatically applied to future orders that follow the same rule. This removes the need for repeated manual updates and helps minimize errors.

Retain Historical Cost Data  

Bloom lets you view product costs in Bloom and Shopify side by side. You can update new product costs directly while keeping all previous cost records intact. This ensures your past COGS calculations remain accurate and your profit reporting stays consistent.

With this level of clarity, you can trust your gross and net profit numbers, giving you accurate profit reporting you can rely on.

Conclusion

Accurate COGS is the foundation of reliable profit reporting. While Shopify’s default COGS settings work for many stores, higher-end businesses often need flexibility.

With a system that updates costs as they change, you can calculate COGS accurately, understand your margins clearly, and make smarter decisions, whether that’s adjusting prices to protect profits or investing in products that deliver the best returns. 

If you're struggling to get on top of your COGS in a way that makes sense for your business, just book a call. We would be happy to help you figure out a way forward.