Inventory Days

Inventory Days is a crucial parameter for all SME owners, SMB owners, and startup owners. It determines how many days a firm will take to transform its inventory into sales. The firm’s ability to convert its resources into cash flows is indicated by Inventory Days.

 Inventory Days in Businesses

What are Days in Inventory?

The average time for which a company holds its inventory before selling it is determined by ‘Days in inventory’. Other names prevalent in some organisations are ‘days inventory outstanding’ or ‘inventory days outstanding’ or ‘inventory days of supply’. Once ‘days in inventory’ is determined, a company can comprehend its efficiency in terms of finances and operations. Moreover, it denotes how swiftly a company can sell its inventory.

If the inventory figure is small then it implies that the company is quickly trading its goods for cash. Ultimately, it indicates that the company is operating efficiently. There may be a situation in which a company discovers that its conversion via sales is slow. The same can depict which areas may demand extra assistance. For example, areas like developing or reforming a brand image or acclimatising to modifications in the industry may need additional help.

 Inventory Days in Businesses

What is Days Sales in Inventory (DSI)?

Occasionally known as days in inventory or inventory days, Days Sales in Inventory (DSI) is a parameter that evaluates the average time or number of days a business needs to transform its stock into sales. For calculation purposes, products regarded as “work in progress” (WIP) are covered in the inventory.
DSI is a principal component of a company’s potential to handle its inventory. It is crucial for businesses because it facilitates management to monitor inventory and evaluate the rate of inventory turnover.
To calculate the DSI value, divide the inventory balance (comprising work-in-progress) by the cost of stocks sold. The result is subsequently multiplied by the number of days in a particular year, quarter, or month.

The DSI value signifies the average number of days a company’s inventory resources are recognized in sales in the year. This value also helps determine the cash conversion cycle (the average number of days a company takes to transform resources into revenue.

The formula of DSI is as below:
DSI = (Inventory /Cost of Sales) x (No. of Days in the Period)

 Inventory Days in Businesses

Inventory Days of Supply

This metric is an efficiency ratio commonly recognized as the Inventory Period or Days in Inventory or Days Inventory Outstanding or Days Sales in Inventory. This metric helps evaluate the average time a company takes to sell its whole inventory. In other words, this metric implies the average time in days during which a firm or warehouse holds its stock before shipping it.

Alternatively, this metric depicts the average time between a company purchasing the goods and selling them to customers. When it comes to the manufacturer, evaluate the average time between acquiring raw materials and selling the final product to a distributor.
Generally, Inventory days of supply are used for work in process (WIP), raw materials (RM), partially finished goods (PFG), and fully finished goods (FFG).
Formula to calculate inventory days of supply:
Inventory days of supply = Average inventory/ the cost of goods sold (COGS) in a day.

Inventory days of supply are inversely proportional to the company’s efficiency at selling goods. So, this is what companies are on the hunt for i.e., they aim to sell their goods in the shortest time possible.
If this metric shows a large number, then the reason is that trading is facing a slowdown. If a company’s inventory turns out too excessive, it is because the company continues restocking despite poor sales.

What is the Formula for Inventory Days and Why is it Useful?

When researching ‘Inventory days’, one of the prime terms you will come across is ‘Inventory days formula’. To gauge sales of a particular product, it is crucial to determine how much its demand is. The ‘Inventory days’ metric evaluates how long a specific product stays in storage before getting sold. If this metric shows a huge number, then it implies that the product is not much in demand. Hence, the product may be costly, or the company needs to modify the way it promotes.

Significance of Inventory Days:

The time the company requires to transform its inventory into sales can be estimated from this metric.
Primarily for distribution businesses, this metric is helpful because it permits an accurate sharing of storage costs for inventory.
If each item spends less in inventory, then the storage cost is lower.
Here’s the formula to calculate the inventory days ratio:

Inventory days = 365 / Inventory turnover
Knowing the inventory turnover ratio is unavoidable for this calculation.

The formula to calculate inventory turnover is as below:

Inventory Turnover = Cost of Goods Sold / Inventory

You need to use the number of days in a specific period and then divide it by the inventory turnover. Using the above formula, you can instantly measure the sales performance of a particular product.

Alternate formula to calculate Inventory days:
Inventory days = 365 x Average inventory

Let’s take an example to clear confusion on how to calculate inventory days. Suppose a company’s inventory is worth $44,500 and its cost of goods sold (COGS) is worth $373,500.

So, the inventory days calculation is as below:

So, Inventory Turnover = $373,500/ $44,500 = 8.393

Now Inventory days = 365 / Inventory turnover i.e. 365/8.393 = 43.49

Therefore, Inventory Days = 43.49 which implies that the company had 43.49 inventory days on hand.

 Inventory Days in Businesses

How to Calculate Days in Inventory (With 3 Examples)

How rapidly a company can sell its inventory for cash can be inferred from a metric known as ‘Days in Inventory’. In other words, it is the average time a company holds its inventory before selling it.
It is crucial to calculate days in inventory because it denotes how efficiently the company operates. Based on that, you can bring in necessary modifications if the company functions inefficiently.

If you want to calculate days in inventory, you need to divide the average inventory cost by the cost of goods sold (COGS). The number which you thus obtained needs to be multiplied by the period (usually 365 days).

The formula for Inventory Days calculation:

Days in inventory = (average inventory /cost of goods sold (COGS)) x period length.

The following section describes each parameter involved in the above formula:

  • Average inventory: This metric denotes the number of units a company classically holds in inventory.
  • Cost of goods sold: It is the money the company needs to yield the products in its inventory.
  • Period length: It mentions the amount of time you intend to calculate days in inventory. Usually, its value is 365.

Let’s go through a few examples of how to calculate days in inventory so that you get a deeper understanding:

Example 1

‘Company A’ sells raw materials for furniture. Suppose the company has an average inventory of $800 and the cost of goods sold is $28,000 for that year. Now how to calculate days in inventory for a period of one year? Well, let’s use the above formula. So, Days in inventory = ($800/$28,000) x 365 = 10.43 days. Since the number denotes a low result, it implies that ‘Company A’ operates efficiently in its market and maintains its finances.

Example 2

‘Company B’ runs a grocery store that offers food products to a town. Suppose this company has an average inventory of $1500 for that year, and the cost of goods sold is $14,000. For this case, the days in inventory are calculated as follows:

Days in Inventory = ($1500/$14,000) x 365 = 39.11 days.

This figure is high for a grocery store, so corresponding administrators can adapt their operations to make them more efficient in terms of finances and operations.

Example 3

‘Company C’ provides repair services and sells spare parts to various mechanics. Suppose its average inventory is $4,000, and the corresponding cost of goods sold for the particular year is $60,000.

Let’s calculate days in inventory as follows:

Days in Inventory = ($4000/$60,000) x 365 = 24.33 days.

It implies that ‘Company C’ has a low result for Days in Inventory, so it is operating efficiently and monitoring finances well.

Five Steps to Calculate Days in Inventory

To obtain a clear picture of how to calculate days in inventory, one must follow the below steps:

Step 1: Find out the average inventory

The foremost step is to determine the average inventory for the company for which you intend to calculate ‘days in inventory’. For that, add the number of inventory units a company holds at the commencement of the period to the number of inventory units available after the period. Now you simply need to divide that number by two to get the average.

For example, a company holds $13,000 in inventory at the beginning and ends the year with $5,000 of inventory.

So, the average inventory = ($13,000 + $5,000)/2 = $9,000.

 Inventory Days in Businesses

Step 2: Calculate the cost of goods sold.

The next step is to determine the cost of goods sold, for which you need to add the cost of goods to the inventory value at the start of the period.

Note that this parameter can involve the expense of labor, materials, and other costs the company incurs while manufacturing goods. Now subtract the inventory value retained at the finish of the period you are calculating.

For example, the above company (discussed in step-1) records a cost of goods as $2500 then the cost of goods sold is calculated as
Cost of goods sold (COGS) = ($13,000 + $2500) – $5,000 = $10,500.

 Inventory Days in Businesses

Step 3: Calculate the period length

The next step involves choosing the period length for which you want to determine the days in inventory. Remember that you must denote the period length as the number of days.

For example, if you intend to determine a period of two months from April through May, the period length would be 31. Some other companies consider a period of one year so that would be 365.

 Inventory Days in Businesses

Step 4: Divide the average inventory by the cost of goods sold (COGS)

In this step, you need to divide the average inventory value by the cost of goods sold. When you carry out this division, you accomplish the first portion of the two-step formula used to calculate days in inventory.

For example, for the example above, the average inventory i.e., $9,000 is to be divided by $10,500 i.e., COGS.

So, $9000/$10,500 = 0.86

 Inventory Days in Businesses

Step 5: Multiply the results by the period length

The final step suggests that you use the result obtained in step-4 to determine days in inventory. So, you need to multiply the number you got in step-4 by the number of days in the period.
Since the company taken as an example has a period length of 365 days, the inventory days are finally calculated as:

Inventory days = 365 x 0.86 = 313.9

Since the above result denotes a high number, the company can adopt some strategies to improve its operations.

 Inventory Days in Businesses

What are Inventory Days On Hand?

For any supply business, it is crucial to manage an inventory. It is inevitable to determine how long the company’s inventory would last and then plan accordingly.

It is essential to know how long one’s inventory will last and design a strategy accordingly. ‘Inventory days on hand’ is a decisive metric of the business cycle; therefore, one must know its functioning. Its alternate name is ‘days of inventory on hand’.

Essentially, it is a measure of time a company needs to expend a stock of inventory on average. Based on the values of the current and exact value of inventory days on hand, a company can decrease its ‘stockout days.’ If this metric shows a lower number, it would be valuable for the company.
If stock levels are accurate, your customers can expediently purchase the product without delays, irrespective of the demand. Overseeing inventory days on hand will assist a company with tracking, forecasting, and calculating the period for which the existing inventory stock will last or become exhausted.

Combining inventory days on hand and forecasting can assist a company in rapidly concluding the products sold on average. Moreover, it can accurately forecast future inventory levels.

 Inventory Days in Businesses

Importance of Inventory Days On Hand

Managing inventory is the critical pillar for supply businesses. As more and more companies acquire customers globally, it becomes challenging to predict the inventory count, manage inventory, and manage inventory costs. Moreover, the high number of sales noted during different festive and season-end sales further increases the complexity of managing inventory. In such cases, several companies can face the peril of running out of stock.

Apart from the expected growth in numbers for these supply companies, the increased quantum of sales during various festivals and season-end sales adds to some companies’ challenges. Firms can face the severe peril of running out of stock. Consequently, it distracts customers from another company, and the business incurs a loss of a substantial number of customers.

Customers may withdraw their orders due to inventory delays or ‘running out of stock’. On the other hand, others may post negative reviews for either the product, company, or both.

The following three points illustrate the significance of inventory days on hand.

Reducing Costs

If the number of inventory days on hand of a company is lower, it would need to expend less money on warehousing facilities. Moreover, the cost of its upfront inventory investment decreases significantly. The low value of inventory days on hand also implies low inventory storage cost (based on where the company determines to stock its inventory).

Instantaneous Profits

Any business always aims at fetching profit as fast as possible. If the company accelerates the speed it goes through its inventory, then it ultimately decreases the inventory days on hand. Consequently, the company can quickly move its inventory and boost its sales value. Therefore, this approach helps earn instantaneous profits.

Reduced Occurrence Of ‘Running Out Of Stock’

When the inventory days on hand are being calculated precisely, it is possible to record precise recorder points. This aids the company in having the correct amount of stock most of the time.

The fewer occurrences of ‘running out of stock’ ensure the company can anticipate a more reliable customer experience and affirmative feedback. No longer need to provide ‘out of stock’ notice to customers.

 Inventory Days in Businesses

What Is Days Inventory Outstanding? (DIO)

One of the prime metrics retailers require for comprehending their business’s performance and success is the Days inventory outstanding (DIO). It measures the number of days a company holds its inventory before selling it. Alternate names of this metric are ‘days in inventory (DII)’, ‘days sales of inventory (DSI)’, the inventory period’, and ‘inventory days of supply’.

This metric signifies how rapidly a company can transform its inventory into cash. Essentially, it is a liquidity metric, or you can consider it as a measure of a company’s efficiency from financial and operational viewpoints.

Here are the three key advantages of determining DIO:

  • Improved understanding of capital
  • Advise marketing and pricing verdicts
  • Prevent overstocking and understocking

Days Inventory Outstanding Formula

The formula to calculate days inventory outstanding is:

Days Inventory Outstanding = (Average inventory / Cost of sales) x Days in Period


Average inventory = (Inventory at beginning + Inventory at end) / 2
Cost of Sales is also identified as Costs of Goods Sold (COGS).

Days in Period are the number of days considered for calculation; it can be a week, quarter, or yearly.

 Inventory Days in Businesses

Example Of Days Inventory Outstanding

Suppose a company needs to evaluate DIO of three brands. The following examples calculate DIO of each brand:

(Note: Days in Period = 365 days for all brands considered for calculation below)

DIO for brand 1:

Suppose brand 1 has average inventory of $2,000 and cost of sales as $23,000.

Its DIO = ($2,000/$23,000) x 365 = 31.74 days

DIO for brand 2:
Suppose brand 2 has average inventory of $1,500 and cost of sales as $60,000.

Its DIO = ($1,500/$60,000) x 365 = 9.125days

DIO for brand 3:

Suppose brand 3 has an average inventory of $4,000 and a cost of sales of $43,000.

Its DIO = ($4,000/$43,000) x 365 = 33.95 days

By determining the DIO of each of these brands, a company can quickly know which brand performs well relative to others. From the above example, it is inferred that Brand 2 is performing very efficiently, whereas Brand 3 shows poor performance. The company’s administration can discuss with the sales and marketing team how to enhance sales of these brands. Moreover, the company may cancel Brand 2 since its performance is the poorest.

 Inventory Days in Businesses

What does a high or low Days Inventory Outstanding mean?

A high days inventory outstanding specifies that a company is incapable of rapidly transforming its stock into sales. Its reasons can be the acquisition of a lot of inventory or poor sales performance.

A low days inventory outstanding specifies that a company can more rapidly transform its inventory into sales. Hence, a low DIO indicates a more efficient sales performance and inventory management business.

Too low inventory is disadvantageous to a company because the stock might turn obsolete and inferior. On the other hand, holding surplus inventory negatively influences the company’s capital.

 Inventory Days in Businesses

How To Improve Days Inventory Outstanding?

The below strategies help to improve days inventory outstanding:

Enhance Forecasting:

When a company improves demand forecasting, it becomes more confident that it is ordering the correct stock quantity. Hence, it will not take much time to sell. The particular company can analyze its POS reports and emphasize historical sales to know how long the products will stay in stock.

Eliminate Dead Stock:

Giving away dead stock will reduce DIO value and benefit from a tax deduction for the value of the stock. If a company donates dead stock to a cause for customers to look after, it will provide a good PR. Informing customers about the dead stock via marketing channels can help accomplish this.

Boost Marketing:

The company can provide a marketing boost to products with low sales. It is recommended to feature them in social media posts, store displays, and sales. Moreover, it is excellent if slow-moving products are bundled with bestsellers to let them sell quickly.


We have discussed in detail Inventory Days and related parameters in this article. These parameters determine how efficiently a company can convert its resources into cash flows. They let the company analyse whether or not amendments need to be done to increase its overall working efficiency.


Sign up, and we will get back to you within 24 hours to discuss what services would be best for your business needs. Or speak with us now and tell us what you need.


A good days of inventory is desirable to competently manage inventories and balance futile stock with being understocked. Its range is 30 to 60 days, and it varies by company size, industry, and other aspects.

Inventory days should be low to let a business perform efficiently in terms of inventory management and sales performance. If the value of this metric is high, the inventory turnover is low. So, a company cannot quickly convert its inventory into sales. This can be because of the purchase of excessive stock or reduced sales performance.

Inventory turnover days are the number of times a company has traded and substituted inventory during a specific period. This metric assists a business in making improved decisions on manufacturing, pricing, buying new merchandise, and marketing.

Inventory Days Outstanding represent the number of days the company takes to sell its inventory. It specifies the number of days for which money is reserved in inventories. Moreover, this metric illustrates how rapidly a company can convert inventory into cash. A company’s financial and operational efficiency can be assessed from this metric.

To find Days in Inventory, you need to divide the average inventory retained during the period by the cost of sales of the company during that accounting period. Now the obtained result is to be multiplied by the number of days in that period (usually 365 days in a year).

The formula to calculate Days in Inventory is:

Days in Inventory = Average Inventory / Cost of Sales * 365

Up to $250K USD Credits for Locad Customers!

Sign up today and accelerate your growth with Locad’s Partners. Unlock deals across SaaS, Agencies and more.

Exclusive benefits to ace your e-commerce game this 2023 with Locad’s desk calendar!