How to manage and calculate your cost of sales

How to manage and calculate your cost of sales

At the beginning of 2021, there were 5.5 million small businesses across the UK. Almost 80% of these small businesses consider maintaining cash flow one of their top challenges.

Cash flow can be hard to manage when you don’t know how money moves around your business. And one of the most critical metrics you must measure for this task (especially when selling physical products) is cost of sales.

Keeping your finger on the pulse of your financial data doesn’t have to be daunting. In this article, we’ll walk you through what cost of sales is and how to calculate it.

Top Tip: Cash flow is the lifeblood of your small business, no matter what stage you’re at. A cash flow forecast can predict your financial situation and help you make smarter business decisions. Check out our guide to what a cash flow forecast is and how to create one 💳

Table of contents

What is cost of sales?

Cost of sales, also commonly referred to as cost of goods sold (COGS), is the total amount it takes to manufacture, create and sell a product. As a result, the only businesses that need to monitor this metric periodically are those that carry physical inventory.

While the definition of cost of sales is straightforward to understand, the calculation can be complicated depending on your products. The cost of sales formula includes various direct and indirect costs, which can complicate the calculation.

Because cost of sales is considered a “necessary expense” to keep your business running, you must include it as an expenditure on income statements. You’ll also need cost of sales to calculate your company’s gross profit and gross margin.

To recap, the key takeaways are:

  • Cost of sales is the cost of producing the products your company sells
  • Cost of sales is deducted from sales revenues to calculate gross profit and gross margin

Top Tip: Accounting can be a daunting task when starting your business. However, you must understand (at least at a high level) the three main financial statements. To learn about balance sheets, income statements and cash flow statements, as well as general accounting processes, check out our complete guide to accounting for startups 📏

What to include in your cost of sales

To calculate your cost of sales, you must ensure you include all direct and indirect expenses incurred when making and selling your products.

Before we look at the cost of sales formula, let’s explore the three values you’ll need to complete the calculation: beginning inventory, ending inventory and new inventory.

Beginning inventory for the year

Your beginning inventory includes products you have when you start a new accounting period, which is often when you begin a new fiscal year. This amount will correspond to what your inventory is worth.

Then there are purchases. Purchases are the new products you buy or produce to add to your inventory throughout the year.

The term “beginning inventory” encompasses several items, including:

  • Inventory leftover from the previous year (i.e. products that didn’t sell)
  • Raw materials used to make your products
  • Related supplies (i.e. packaging)

how to calculate the cost of goods sold

To establish a starting point for your cost of sales calculation, you’ll need the value of your beginning inventory for your accounting period. Use your accounting records to calculate this number, and use that in your beginning inventory calculation for your current sales period.

Let’s look at an example of how to calculate beginning inventory:

Linda runs an apparel business and relies on a third-party supplier to produce the t-shirts she sells.

Last year, Linda purchased 1,000 t-shirts and sold 500 of them. It cost Linda £3 per t-shirt. So, Linda’s cost of sales last year would be:

Cost of sales = Cost to produce each product X Number of products

£3 X 500 = £1,500 (Cost of sales)

At the end of the year, Linda was left with 500 unsold t-shirts. Therefore, she would calculate her ending inventory as follows:

Ending inventory = Cost to produce each product X Number of products

£3 X 500 = £1,500 (Ending inventory)

She also ordered another 600 t-shirts as new inventory for the upcoming year, which cost her £3 each.

New inventory = Number of new products X Cost to produce/purchase each product

600 X £3 = £1,800 (New inventory)

To accurately calculate Linda’s beginning inventory, we first need to add up Linda’s ending inventory and cost of sales from the previous year.

£1,500 + £1,500 = £3,000

Now, we can get Linda’s beginning inventory for the new sales year by subtracting the cost of those new t-shirts she ordered from the ending inventory figure above:

£3,000 – £1,800 = £1,200

Linda’s beginning cost of inventory for this year is £1,200.

Ending inventory

As we covered above, your ending inventory is the value of the product in stock at the end of your accounting period. Businesses typically determine this by taking a physical count of inventory at year-end.

Going back to Linda, her ending inventory was the value of all the t-shirts she had left at the end of her sales year.

To recap, the calculation is:

Ending inventory = Number of products X Cost to produce each product

Linda had 500 leftover shirts that she purchased for £3 per piece, so her ending inventory calculation is:

500 X £3 = £1,500

cost of sales infographic

cost of sales infographic

Top Tip: If you want to save money for your business, pay the correct amount of tax and improve the overall health of your SME, you need to manage your expenses effectively. To learn more about business expenses, what you can claim back and how to do so, read our guide on what expenses are and how small businesses can manage them 😀

Cost of sales formula

Now that you have a deeper understanding of what contributes to your cost of sales, let’s put all of them together into the final formula:

Cost of sales = (Beginning inventory + Purchases) – Ending inventory

But before we dive into an example, your cost of sales formula will vary depending on how you (or your accountant) manage your inventory cost method. 

Do you typically sell items that were manufactured or purchased first, last, or neither? Your answer will determine which of the three following inventory cost methods you use:

  • FIFO (First In, First Out)
  • LIFO (Last In, First Out)
  • Weighted-Average Cost


With the FIFO method, the earliest manufactured or purchased goods are sold first. Given prices tend to go up over time, you will sell your least expensive stock first—first in, first out. 

This method is best if you sell products that have a short shelf life. 


The LIFO inventory cost method is the opposite of FIFO. With this method, the most recently manufactured or purchased goods are sold first. 

During a period of inflation, you will sell your inflated items first—last in, first out.

Weighted-Average Cost

With this method, the average cost of all goods is used, regardless of when the items were manufactured or purchased. 

The Weighted-Average Cost method is ideal if you sell mass-produced items. 

Here’s an example of how your cost of sales will vary depending on the inventory cost method you use:

FIFO vs LIFO vs weighted average cost

FIFO vs LIFO vs weighted average cost

Example of cost of sales formula

With the previous information, you now have a high-level understanding of the cost of sales formula, its three main components, and how to put them together.

To calculate a true cost of sales, we need to include direct and indirect costs. These can be defined as:

  • Direct costs. The costs incurred sourcing materials and getting your products built.
  • Indirect costs. These include the cost of promoting your products, employees, software and other overheads.

The cost of sales formula allows businesses to calculate how much they spend to get their products built and sold, regardless of whether they manufacture the products themselves or simply resell.

Calculating cost of sales also allows you to see exactly how much you’re spending per product to make a sale (and ensure you price products accordingly). And remember, you’ll also deduct the cost of sales on your business tax return. So, getting this number right is crucial.

When examining the cost of a product, you must consider more than the superficial cost to buy or manufacture it. You’ll need to include multiple direct and indirect costs into this number, including:

Direct costs: Related to production or purchasing products for resale

  • Cost of raw materials (if you make your products)
  • Any supplies needed for production
  • Overhead costs related to production (i.e. rent or utilities for a manufacturing facility)
  • Cost to purchase products for resale
  • Cost of all packaging

Indirect costs: Related to facilities, Equipment, Administrative and Labour

  • Costs to store products (i.e. warehouses)
  • Costs to wholesale products
  • Wages for workers who build, manufacture and help sell products
  • Distribution costs
  • Salaries for managers who oversee production
  • Any equipment for administrative work
  • Any depreciation on equipment used to produce, store or package products

Once these costs are factored into the cost of producing inventory items, it’s easier to calculate the cost of sales accurately.

To walk you through the cost of sales formula, let’s refer to our example with Linda’s t-shirts (assuming direct and indirect costs have been included in these calculations).

Cost of sales = Beginning inventory + Purchases – Ending inventory

Cost of Sales = £1,200 + £1,800 – £1,500

Cost of Sales = £1,500

Based on this cost of sales formula, Linda’s cost of sales for her T-shirts is £1,500.

Other considerations for cost of sales

While there’s already more than enough to consider when calculating the cost of sales for a business, there are some additional things for you to keep in mind:

  • The only businesses that need to track cost of sales are those that sell physical products. For service-based businesses or those that don’t carry inventory, this isn’t a crucial metric.
  • If a business hasn’t generated sales, it can’t deduct from its cost of sales. Even when it’s purchased or manufactured products to sell.
  • When valuing the cost of your inventory, don’t forget to factor in facility costs. After all, a business often pays rent and utilities for the location where products are made and/or sold. Those costs need to be accounted for to ensure you’re ROI positive.
  • These calculations can be complex for a business owner to handle, which is why getting guidance from a small business accountant can go a long way. Consult with an accountant or bookkeeper to double-check your calculations or simply leave it with an expert.

Top Tip: Accountants and bookkeepers can provide unique insights into your financial situation and make informed suggestions for the future. To find out why you might need one, and which is better suited to your requirements, read our guide on the difference between an accountant and a bookkeeper 📤

💡Expert insights

Insights author: Wesley Griffith, Managing Director of Virtual Finance Team Ltd

Wesley has worked with an array of businesses in various industries as Finance Director, Managing Director, Group Financial Controller and Practice Accountant.

He and his team provide a multitude of support services to businesses across the UK. They help with things from outsourcing complete accounts departments up to placing a part-time or virtual Finance Director, helping to add structure, process, planning and profit improvement to small businesses.

Why is it important to calculate cost of sales?

If you want to manage the profitability of your business and add to your bottom-line profit, you must understand how to calculate and interpret your cost of sales. 

To calculate gross profit in your business you must first consider the costs.

The costs in any business are spread between two main categories: cost of sales and overhead costs.

It is important to differentiate between the two to understand the true profitability of your business.

If you get the cost of sales right, then the overheads of your business should be relatively constant, allowing the cost of sales to increase and decrease in line with the sales of the business.

For a retail business that sells items, the cost of sale is the item itself, which includes the cost of getting it from your supplier to you and any expenses (e.g operating expenses, administrative expenses, direct labour costs) that make it sellable.

For a manufacturing business, this would include raw materials, time spent on manufacturing, and other associated production costs.

If you can reliably track your cost of sales, then you will be able to understand whether your trade is improving or not. By having clarity on what makes you money and what doesn’t, you can make decisions to improve your business’s profit.

Tips to keep on top of your cost of sales

Regularly compare your gross profit against a previous period. If this gross profit percentage decreases, you may need to look at your cost of sales to drive costs down with external suppliers or scrutinise the usage of material in this area.

Here are a few tips to help you do this:

  • If you record time into your cost of sales, then try and keep to the budgeted time allowed for the job you are doing.
  • Value engineer or switch products to keep costs down but ensure the quality stays the same.
  • Quote or estimate correctly, as simple as it sounds, knowing that you have enough money above and beyond your cost of sales is key to keeping your costs down compared to your sales price.
  • Regularly review supplier prices and compare against their competitors.
  • Look at cost controls and improve where you can.
  • Always look for improved efficiencies in the production process.
  • Encourage staff to be more efficient and mindful of waste.

Top Tip: One of the best ways to prepare for extra costs is to budget effectively. Without a solid budget, it’s easy to get carried away with spending and assume future revenue will cover initial costs. Learn what business budgeting is all about, why it’s important and how to get started with our 8 steps to create an effective business budget 📑

Wrapping up

Now that you have a better understanding of how to calculate your cost of sales, you can make more informed, data-driven decisions about your business.

To recap, here’s what you must consider when calculating your COS:

  1. What to include. This includes inventory at the beginning and end of the year, as well as any purchases (i.e. the products you buy or produce).
  2. Calculating cost of sales. Use the formulas we’ve provided throughout this guide using purchases, as well as all direct and indirect costs.

These formulas and calculations will help you figure out your profit margins, forecast your cash flow and maintain profitability.

Top Tip: Managing your cash flow is more important than ever. To learn how to master your cash flow and maximise your chances of getting paid on time, catch up on our Masterclass series and step-by-step guide to mastering your cash flow 📹

Photo by Ellicia, published on Unsplash

Adelaide Carleton

Adelaide Carleton

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