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Days sales inventory (DSI): The ultimate guide

This article offers a detailed guide on days sales in inventory (DSI), providing insights into its calculation, significance, and how it influences business decisions.

June 19, 2024
15 min read
Ioana Neamt

Ioana Neamt

Contributing Writer

Days sales inventory (DSI) isn’t just a buzzword in the business world; it’s a game-changer for companies looking to get a handle on their inventory. This guide breaks down the ABCs of DSI, a key metric that can make or break a company’s inventory strategy.

Whether you’re a startup guru or new to the inventory scene, we’re unpacking everything you need to know about DSI. It’s all about turning stock into cash flow and keeping your business agile in a market that never sleeps. Get ready to dive into how DSI works, why it matters, and how nailing it can set your business apart from the crowd.

What is Days Sales of Inventory (DSI)?

DSI is like a crucial app for businesses, showing how fast they’re selling their stock. Think of DSI as a gauge that measures how quickly products move from warehouse to customer. In industries where trends are as fleeting as the latest app update, a speedy DSI is vital. It’s akin to having high-speed internet in a digital landscape — absolutely essential to stay competitive.

A low DSI signals success. It indicates high demand and efficient inventory management, crucial in sectors like e-commerce or for products with short lifespans. This is comparable to a startup swiftly adapting to market shifts.

On the contrary, a high DSI is a warning, suggesting slower sales, akin to an app struggling to gain users. It could point to overstocking or products not aligning with customer preferences, tying up funds that could be used for innovation or growth.

However, the ideal DSI varies across industries. For instance, luxury car manufacturers may have a higher DSI compared to fast-fashion retailers, similar to how software development timelines differ from rapid app rollouts. Tech companies should benchmark their DSI against industry standards, using it to sharpen their operational strategies, much like optimizing a tech product for maximum efficiency.

Days Sales of Inventory formula

The DSI formula is straightforward:

The formula uses average inventory as a key component. To get this number, companies look at their inventory at the beginning and end of a period, usually a full year, and average these two numbers. This method is great because it smooths out any ups and downs that happen because of seasonal changes or normal business cycles.

Another important part of the DSI formula is the cost of goods sold (COGS). This number includes all the costs involved in making the products, like materials, the money spent on workers, and other expenses. COGS is crucial in the DSI calculation because it’s directly linked to the products that are sold.

Lastly, the number of days, usually 365 days, is the timeframe used in the DSI calculation. This period is important because it shows the average time a company’s inventory sits before being sold.

A male worker in a warehouse looking into items for decoupling inventory.

Days sales of inventory calculation

DSI is a straightforward process that can be broken down into a series of manageable steps.

1. Average inventory calculation

Firstly, determine your average inventory. This step isn’t too complex. You just need to look at your inventory levels at the beginning and end of a specific period, which could be a month, a quarter, or a year. To find your average inventory, add these two figures together and divide by two. This average will give you a good estimate of the inventory you had during that period.

2. Identifying cost of goods sold (COGS)

The next step is to figure out your cost of goods sold, commonly known as COGS. This is essentially the total cost of making your products ready for sale. It includes expenses like materials and labor used in the production of your goods. It’s important to calculate this accurately as it shows how much you’re spending on your inventory.

3. Deciding the number of days

Now, you need to choose the time frame you want to analyze. Often, businesses look at a full year, which is 365 days, but you can choose a shorter period if it suits your business better. This is like setting a timeframe to see how quickly you turn your inventory into sales.

4. Applying the formula

Finally, you apply the DSI formula. Take the average inventory you calculated and divide it by your COGS. This ratio tells you the amount of inventory you have compared to what you’ve sold. Multiply this ratio by the number of days you’ve chosen. The result is your DSI, which helps you understand how long it takes, on average, to turn your inventory into sales.

Why is DSI Important for your business?

DSI offers multiple benefits to businesses, which include:

  • Managing cash flow — A comprehensive understanding of DSI is instrumental in handling cash flows efficiently. By tracking how long inventory sits before being sold, businesses can better predict their cash needs, ensuring they have enough liquidity to cover operational expenses without tying up too much capital in unsold stock.
  • Optimizing inventory levels — DSI aids in maintaining inventory levels. By identifying the average time products stay in inventory, businesses can prevent overstocking, which ties up capital and space, and understocking, which can lead to lost sales and customer dissatisfaction. This balance is crucial for maintaining a lean and responsive inventory system.
  • Enhancing supply chain decisions — DSI provides valuable insights for refining supply chain operations. With a clear understanding of inventory turnover, businesses can make more informed decisions regarding purchasing and production planning. This leads to a more streamlined supply chain, reducing lead times and improving responsiveness to market demands.
  • Improving financial health — A lower DSI often indicates better liquidity and operational efficiency. It suggests that a business is able to convert its inventory into sales more quickly, improving cash flow and reducing the need for external financing. This efficiency can lead to improved profit margins and overall financial health, making DSI a critical metric for assessing a company’s operational success.
A worker in a warehouse holding a tablet

What does DSI tell you?

Inventory efficiency is a critical measure of how well a company manages its stock. It’s about having the right amount of products at the right time — not too much to incur high storage costs or risk obsolescence, and not too little to avoid stockouts and missed sales opportunities. Effective inventory management strikes a balance between these extremes, ensuring that resources are used wisely, and customer satisfaction is maintained.

Market demand is mirrored in the velocity of product sales. A company’s ability to meet, anticipate, and respond to market demand is crucial. This aspect involves understanding consumer needs and preferences, adapting product offerings accordingly, and maintaining an inventory that aligns with current trends and demands. It’s about staying relevant and competitive in a dynamic market environment.

Financial planning is significantly influenced by inventory and sales data. Accurate forecasting and budgeting require a deep understanding of inventory turnover and sales patterns. This information helps businesses plan their financial future, allocate resources effectively, and make informed decisions about investments and growth strategies. By linking inventory data with financial planning, companies can optimize their financial health, ensuring sustainable growth and profitability.

DSI vs. inventory turnover

DSI tells you about the time it takes to sell inventory, showing how fast a business turns its stock into sales. Inventory turnover, on the other hand, looks at how often the inventory is sold and replaced during a period.

When you use both these measures, you get a full picture of how well a business is handling its inventory. This helps in making sure the inventory is managed efficiently, balancing how quickly items are sold with how often new stock is brought in.

Using DSI to your advantage with Katana

Understanding DSI is akin to having a crucial roadmap for proficient inventory management in any business. It serves as a strategic tool to gauge the velocity at which inventory is converted into sales, providing pivotal insights into a company’s operational effectiveness and agility. When paired with the inventory turnover metric, DSI offers a comprehensive perspective of a company’s inventory management prowess.

With Katana, keeping accurate track of your inventory at all times becomes effortless. You’ll be able to reduce inventory costs, streamline internal processes, adjust your business strategy based on data-driven sales trends, and ultimately reduce your DSI metric and keep inventory moving and customers satisfied.

Katana calculates COGS for you, so a part of the DSI calculation is already solved, thus simplifying the process and freeing up valuable time. What’s more, you can easily keep track of all your inventory costs in one place and extract detailed cost reports that help you make informed business decisions.

Reach out to our sales team to request a demo and see how you can optimize operations, manage all your sales channels, and more with our flexible, powerful, and enjoyable cloud inventory software solution.


How often should DSI be calculated?

DSI should be calculated regularly, ideally at the end of each accounting period, which could be monthly, quarterly, or annually. This frequency allows businesses to keep a consistent track of inventory efficiency and make timely adjustments. Regular monitoring of DSI helps in identifying trends, addressing issues promptly, and aligning inventory management with changing market demands.

Can DSI vary by industry?

DSI can significantly vary across different industries. This variation is due to differing business models, product life cycles, and market dynamics. For example, fast-moving consumer goods (FMCG) companies generally have a lower DSI due to rapid inventory turnover, while industries like heavy machinery or luxury goods might exhibit a higher DSI due to longer sales cycles and manufacturing times. Businesses should benchmark their DSI against industry standards to gain meaningful insights.

What can a company do to improve its DSI?

Improving DSI involves several strategies, including optimizing inventory levels to avoid overstocking or understocking. Companies can also enhance their demand forecasting methods, using historical sales data and market trends to predict future sales more accurately. Additionally, streamlining the supply chain by improving supplier relations and logistics can reduce lead times and keep inventory levels in check.

Does a seasonal business need a different approach to DSI?

For seasonal businesses, DSI needs a tailored approach to account for fluctuations in demand. These businesses should calculate DSI for their peak and off-peak seasons separately to gain accurate insights. Understanding these seasonal variances helps in better inventory planning and ensures that the business is not caught off-guard during high-demand periods.

Is DSI relevant for service-based businesses?

While DSI is primarily used in the context of physical goods, service-based businesses can also benefit from a modified version of this concept. For these businesses, it’s about understanding how quickly they can deliver their service and replenish their capacity. This modified DSI can help service-oriented companies optimize their workforce, manage scheduling efficiently, and ensure that they are not over or under-capacity.

Can DSI be used to assess a company’s environmental impact?

Yes, DSI can indirectly help assess a company’s environmental impact. A lower DSI means faster inventory turnover, which can reduce the need for extensive warehousing and potential waste from unsold goods. Efficient inventory management, as indicated by a healthy DSI, can lead to less resource wastage and a smaller carbon footprint. Companies looking to improve sustainability can use DSI as one of the metrics to optimize their operations in an environmentally friendly manner.

Ioana Neamt

Ioana Neamt

Contributing Writer
With more than 10 years of copywriting experience, Ioana has a fondness for longform writing, investigative journalism, cats, and Victorian-style mansions.

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