Merchandise Kardex: What It Is and How to Keep Your Stock Under Control

Merchandise Kardex: What It Is and How to Keep Your Stock Under Control

If you run a business that buys and sells products —a store, a shop, a distributor, a hardware store or a minimarket— you have probably been through this: you are not sure how many units of an item you have left, how many you sold last week, or whether what the shelf shows matches what your notebook says. The classic tool for solving that problem is called the merchandise kardex, and after decades it is still the foundation of every good inventory control system.

In this article we explain what a merchandise kardex is, which movements it records, how to read it with a practical example, and how it differs from your company's general inventory.

What is the merchandise kardex?

The merchandise kardex is an individual record kept for each product: it notes, in chronological order, every unit that comes into the business and every unit that goes out, together with the date, the detail of the movement and the balance left after each one. In short, it is the life story of every article you sell.

If your business handles hundreds of items, you do not need a notebook with hundreds of loose pages: you need each product to have its own history. That is why the kardex is organized by product and not by invoice. The question it answers is not “what did I sell today?” but “what has happened to this specific product since it arrived at my warehouse?”

The classic kardex format includes the date of the movement, the detail or concept (a purchase, a sale, a return), the number of incoming units, the number of outgoing units and the resulting balance or stock. With that information, the balance can always be verified: add the entries, subtract the exits and compare the result with the physical count.

Which movements does the merchandise kardex record?

In a buy-and-sell business, the kardex must capture every movement that increases or decreases the stock of a product. The most common ones are:

• Purchases or inflows: every time you receive merchandise from a supplier, the units enter the inventory and increase the product's balance.
• Sales or outflows: each sales invoice deducts the units sold from the balance.
• Customer returns: when a customer returns an item, the units go back into inventory and the balance is restored.
• Returns to suppliers: when you send damaged merchandise back to the supplier, the units leave the inventory.
• Shrinkage: damaged, expired or lost products must leave the kardex so the balance reflects only what truly exists.
• Transfers: if the business has more than one warehouse or point of sale, moving units between them is also recorded, so each location keeps its own balance.

Every movement is noted with its date and quantity, so the product's history stays complete, organized and easy to audit.

A practical example of a merchandise kardex

Imagine that you sell 1 kg powder detergent in your store. During January, the kardex of that product would look like this:

See how it works: on January 2, 30 units come in and the balance is 30. Each sale subtracts from the balance, and the return on the 12th restores the 2 units the customer brought back, because that merchandise is available for sale again. The shrinkage on January 25, on the other hand, deducts the damaged unit, since it can no longer be sold.

If at the end of the month you physically count the detergent and find 22 units, the kardex matches. If you find fewer, there is a difference you must investigate: something left without being recorded or there is a counting error. If you find more, there are probably unrecorded entries. That is the real value of the kardex: turning inventory into a system that can be verified.

What is the merchandise kardex for?

The merchandise kardex serves, above all, two purposes: knowing how much you have of each product and knowing how much you have sold of each product. With that, a small business owner can answer questions that used to be solved blindly:

• How many units of this item do I have today?
• How many units of this product did I sell last month?
• When was the last purchase and how much did I receive?
• How much has been lost to shrinkage, returns or mistakes?
• Is it time to place a new order with the supplier?

That information protects the business's money in several ways. First, it prevents stockouts: if you know how much you have, you will not sell a customer a product you no longer have, nor promise merchandise you cannot deliver. Second, it prevents excess: overbuying ties up cash in products that may not move. Third, it lets you detect losses early: if the kardex balance does not match what is in the warehouse, something is going on —a theft, an error or a pending entry— and it is better to know as soon as possible. And fourth, it makes it easier to calculate the cost of goods sold, because each outflow is linked to its value.

How is the kardex different from the general inventory?

The general inventory is the consolidated list of everything the company has at a given moment: product, quantity and total value. It is a photograph: it is taken on a specific date —for example, at the end of the month or the year— and shows how much exists in total. The kardex, by contrast, is a movie: it records every movement over time, product by product.

The practical difference is huge. The general inventory tells you “you have 4,500 units worth 38 million”. The kardex tells you “of the 1 kg detergent, 30 units came in, 34 went out, 22 remain, and the last sale was on January 20”. Without the kardex, the general inventory is just a global figure that is hard to explain; with the kardex, that figure can be broken down and verified item by item.

Also, the general inventory is usually done periodically —once a month or once a year— while the kardex is updated with every movement. That is why the kardex does not replace the physical count: it complements it. The count confirms that the kardex tells the truth, and the kardex explains the differences the count finds.

How to keep the merchandise kardex in Kardex Tauro

Keeping the kardex by hand, in notebooks or in spreadsheets is possible, but fragile: a forgotten entry, a wrong sum or a lost page breaks the whole system. That is why in Kardex Tauro the merchandise kardex is generated automatically, so you never have to write anything twice.

Every purchase you record as an inflow updates the product's kardex: the units come in and the balance goes up. Every sales invoice does the same in the opposite direction: the units go out and the balance goes down. Returns restore units to the inventory and shrinkage deducts them, always with their date and detail. And since everything is stored by product, you can view the complete history of any item whenever you need it: when it came in, when it went out, in which document and how much is left today.

With Kardex Tauro, your merchandise kardex is always up to date, and it matches what is really in your warehouse as long as the physical count is done with discipline. That combination —a reliable automatic record plus a periodic count— is what keeps a small business's inventory healthy, without last-minute stockouts or cash sleeping in products that do not move.