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The 20 Best Excel Formulas For Managing Your Product Inventory

September 18, 2023
Bill Kimball

Number of KPIs that can provide insights into how to increase sales or improve the marketability of certain stock or the overall inventory mix. However, knowing when to reorder, how much to order, where to store stock, and so on can quickly become a complicated process. As a result, many growing businesses graduate to an inventory management app, software, or system with capabilities beyond manual databases and formulas. Sortly is an out-of-the-box inventory management software and asset tracking system that can eliminate time-consuming inventory processes for all sorts of businesses. There’s plenty to keep track of when running a product-based business, most notably the management of inventory and everything that comes along with it . To do this well, business owners and executives often turn to standard inventory ratios and formulas to stay organized and keep things running smoothly.

Depending on the product, the time period could be anywhere from a calendar year or a season to weekly . Contra accounts generally consist of purchase discounts or purchases returns, allowances accounts,etc..

Using a safety stock formula helps you to take a data-driven approach to inventory management, maximizing sales and ultimately profits. For most industries, the ideal inventory turnover ratio will be between 5 and 10, meaning the company will sell and restock inventory roughly every one to two months. For industries with perishable goods, such as florists and grocers, the ideal ratio will be higher to prevent inventory losses to spoilage.

Limits Of The Normal Distribution For Your Safety Stock :

With the finished goods formula, you can easily track work-in-process inventory, raw materials, and unfinished goods to ensure your accounting is accurate. These are just some of the things you can glean from using the average inventory formula. The values provided can impact your inventory management in a wide variety of ways. If your lead time variation is small, you will likely have a much lower safety stock because you know your supply will be fairly consistent. On the other hand, if your supply fluctuates dramatically you will require more safety stock to cover these longer lead time periods. To calculate the standard deviation in demand you first need to calculate the average demand, which is the total monthly demand/number of months.

inventory management formula

The most important thing already will be the quality of the data, which is even more important than the method chosen in terms of sales and lead times. If you consider that the request and the lead time are dependent, i. That the lead time causes uncertainty on the request and vice versa, you have the following formula which will sum the safety stock of Formula 1 and Formula 2, giving 377 quantities in our example. There are many ways to calculate safety stock, you can fin hundred of different ways of calculation on google, wikipedia etc …. In this post, we will explain to you the main calculation methods on Excel as well as those I recommend.

Knowing the optimal inventory levels for your business can save you money in the long run. Instead of spending a lot of money on warehousing an excessive amount of raw materials and finished products, you can save by storing only what’s needed. The best part is that figuring out your average inventory is generally simple.

When You Should Use Periodic Inventory Method

It could also mean a surge in popularity of these goods—increased market demand, in other words—so you may want to increase your orders to suppliers before your competitors buy them out. However, it could also mean you’re not buying enough inventory or you lack supply chain visibility, which is limiting the sales you can make. That spells opportunity, if you can increase your stock of popular items. Companies can calculate inventory turnover This standard method includes either market sales information or the cost of goods sold divided by the inventory. However, turnover ratio may also be calculated using ending inventory numbers for the same period that the cost of goods sold number is taken.

These periods can be decided according to you; it could range from a few hours to monthly to annually. This type of method is generally used by small companies that don’t have many stocks to track or slow sales rate. Businesses that don’t have a large number of frequent sales or purchases can also adopt periodic inventory management.

The biggest benefit of using the moving average approach is that it makes it much easier to calculate the average cost of goods sold. If you’re coming into your big season, you’ll undoubtedly be carrying more inventory at the start of that period. Hopefully you’re also carrying significantly less at the end of the season. It’s hard to predict buying behavior, so sales trends and buying habits may not sit perfectly within the mathematical bounds of these formulas. While safety stock will help you to prevent stockouts, they will still occur.

Whether you rely on just a few of the above formulas or all of them to provide a clear picture of your product landscape, formulas and ratios help create consistency for managing your business. Streamlining these calculations as much as possible can save a lot of time and alleviate big headaches. If your business has been expanding gradually and regular inventory counts seem confusing, then you can opt for the perpetual inventory system for smooth inventory management. No additional training for employees –since a perpetual inventory software isn’t required, businesses with periodic inventory systems don’t need to focus on technical employee training. Less expensive –unlike the perpetual inventory system, businesses do not have to invest in specialized software for inventory counting in the periodic system.

Improving Inventory Turnover With Inventory Management Software

It complements other inventory management methodslike ABC analysis, FIFO , LIFO, EOQ, etc. by allowing you to have a proper understanding of inventory flow anytime. After researching in great depth, I finally found the case study of Sulfo Rwanda Industries. It’s an excellent example of the practical applications of the perpetual inventory method. With this formula you can select a range of values and see how they rank, in ascending or descending order.

  • The study finally proved that Sulfo Industries used raw materials such as fuel oil, peat, gypsum, gas-oil.
  • Once you receive the alert, you can replenish inventory with the right reorder quantity needed.
  • In addition, it’s a key calculation in determining how well your inventory is translating into sales for your business.
  • Less expensive –unlike the perpetual inventory system, businesses do not have to invest in specialized software for inventory counting in the periodic system.
  • In this approach, warehouse managers keep a continuous track of inventory balances, which means the stock is updated automatically every time an item is received or sold through every point of sale.
  • Each time a sale or purchase happens, the perpetual inventory method records those changes into the sales revenue account.

Calculating average inventory is a useful accounting measure to track changes and activities over time. This is often a better lens to view a company’s inventory standing than a single point in time or accounting period. Inventory management is key to managing costs and maintaining customer satisfaction.

The Cost Of Goods Sold Cogs

The diversity of retail inventory management adds to its complexity and drives home its importance to your brand. Clarifies the value of your inventory, and it’s useful for several other important inventory formulas as well. It’s also critical data for your yearly tax filing, since it reduces your taxable business income. Calculating stock turn is significant because it clarifies whether individual products are profitable for your business. It’s also a clear indicator of which products have weak sales performance, as well as whether your purchasing levels are on target. However, regardless of the magnitude of your business, you will, at some point, have to carry out a physical inventory count.

Lower DSI is usually desirable, but like inventory turnover ratio this will vary by industry. Benchmark your DSI against peer companies to get idea of performance. Or maybe your business is seasonal—like ice cream in the summer or holiday decorations in winter. Looking at a single point in time won’t necessarily give you an accurate picture of your inventory. Take the revenue from your last fiscal year and compare it to your average inventory from the same time. This will show you how much inventory each month on average you needed to supply and support that amount of sales. You could perform the same exercise for any given period—year-to-date, a quarter or even a month.

Last in first out is the cost flow assumption that is used by business to calculate the worth of their inventory. This method also uses the running ledger tally for purchases and sales. The only difference is that here the last-placed stock is sold first, and thus the leftover inventory is the inventory that was purchased first i.e. the oldest one. FIFO is a method to account for an inventory in a way that the stock purchased first will be sold first so that the leftover inventory is always the recently purchased inventory.

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As we touched upon earlier, safety stock acts as an emergency buffer you can break out when it looks like you’re on the verge of selling out. You want to have enough safety stock to meet demand, but not so much that increased carrying costs end up straining your finances.

Also check out our articles on the ABC method and Wilson’s Formula, which will help you better understand and apply these methods. Quickly, the normal distribution is a mathematical law that will make it possible to predict the probability of selling a certain quantity.

Safety stock management is a critical part of being a retailer and a manufacturer. It will help to reduce the chance of stock outs, which lead to inefficiency, unhappy customers, and ultimately, lost sales and reduced profits.

Hassle-free –periodic inventory system requires physical inventory counts after a specific interval of time. Considering the periodic inventory system and perpetual inventory system, the latter is more complicated where inventory needs to be tracked with every sale. The cost of products sold can be calculated by using either the periodic inventory formula method or the earliest cost method. The company makes a physical count at the end of each accounting period to find the number of units in ending inventory. The company then applies a first-in, first-out method to compute the cost of ending inventory. Use of technology-Perpetual inventory system uses perpetual inventory system software for real-time inventory tracking. Products are scanned with the use of barcode scanning for accurate inventory levels.

Service level plays a key factor when calculating safety stock which is what you are trying to maintain. A 100% service level would mean you always have stock, which is a risk in itself and varies in demand. For example, if you sell an average of 1000 quantities, you have a high probability of selling around 1000 and you have a much lower probability of selling 500 or 2000, for example.

By knowing the amount of finished inventory on hand, your small business can accurately determine stock levels for improved inventory tracking. This equation tells us that we need 870 units of safety stock on hand to meet the demand of sales over an average lead time of eight days, while maintaining a service level of 90%. The inventory turnover ratio is the number of times a company has sold and replenished its inventory over a specific amount of time.

If the supply and demand are consistent, you may not require large amounts of safety stock. For some retailers, a safety stock calculation can simply be a gut-feeling, an educated guess at what they think is right. However, this isn’t recommended as it can cause issues with stock outs causing customer frustration and lost sales. This safety stock is more important because it takes into account both uncertainty about lead time and sales. For example, if you want an average service rate of 50%, you don’t need safety stock because you have a 50/50 chance of selling more or less than the average next month. The first method I will present is the basic method, which I also call “the old-fashioned way”.