Warehouse kardex

In any business that handles physical merchandise, someone needs to answer the same question every day: how many units of this product do we have? The answer may come from a quick count, from the person in charge remembering, or from the movement record that is updated with every purchase and every sale. That third option, kept with discipline, is exactly what a warehouse kardex does. If your stockroom control depends on notebooks, loose sheets or quick notes, and every time you need to know a balance you have to walk over and look at the shelves, this article is for you. Here you will learn what a warehouse kardex is, what it is for, what data it must contain, how it is used in the daily operation of the stockroom and why it is the warehouse keeper's main working tool. At the end you will find a practical example with real stockroom movements.

What is a warehouse kardex?

A warehouse kardex is a chronological, organized record of every movement that affects the physical stock of the products kept in a stockroom or warehouse. It logs the inflows (purchases, customer returns, overages), the outflows (sales, internal use, shrinkage, returns to suppliers) and the unit balance left available after each transaction. Its purpose is not to keep cost accounting but to control physical stock: knowing what merchandise is on hand, in what quantity, where it is stored and how it has changed over time. That is why it is also called a stockroom card, a stock card or an inventory card. It can be kept on paper, in a spreadsheet or in inventory software, but the logic is always the same: every movement of merchandise must be recorded and must update the balance. In short, the warehouse kardex is the written memory of the stockroom. If you ever need to explain why units are missing, when a batch arrived or who received a shipment, it is the first place to look for the answer. Without that record, stock control becomes a permanent guess.

Differences between the warehouse kardex and the accounting kardex

It is very common to confuse the warehouse kardex with the accounting kardex, also called the valued kardex. Both record inflows and outflows of merchandise, but they serve different purposes and are usually handled by different people. Knowing the difference avoids misunderstandings about who should keep each record and what each one is for. The accounting kardex works with monetary values: besides units, it records the cost of every inflow and outflow, calculates the cost of goods sold and feeds the company's financial statements. It is managed by the accounting department and applies inventory valuation methods such as weighted average or FIFO. The warehouse kardex, on the other hand, works with physical units and does not need prices to do its job. It is an operational tool for the warehouse keeper to control stock: it tells them how many pieces are on hand, where they are stored and whether it is time to order more, without getting into accounting figures. The main differences are summarized below:

Purpose: the warehouse kardex controls physical stock; the accounting kardex values inventory and calculates costs.
Main information: units and locations, versus units and monetary values.
Person in charge: the warehouse keeper in the first case; the accountant in the second.
Valuation methods: not applicable to the warehouse kardex; they do apply to the accounting one (weighted average, FIFO).
Destination of the information: purchasing decisions and daily operations, versus reports and financial statements.

Even though they are different records, they complement each other. When a company uses integrated inventory software, a single movement — a purchase or a sale — can update both the physical control of the warehouse and the valued kardex used by accounting at the same time, without entering the information twice.

What data must a warehouse kardex include?

For a warehouse kardex to be truly useful, it must identify each product and each movement without ambiguity. A good format includes, at minimum, the following fields:

Product identification: code or reference, description, unit of measure (units, kilograms, boxes) and presentation.
Warehouse location: aisle, rack, module or position where the item is stored, so it can be found without walking through the whole warehouse.
Date and type of movement: the day of the transaction and its kind: purchase, sale, return, transfer or adjustment.
Inflows: the units that entered the warehouse.
Outflows: the units that left the warehouse.
Physical balance: the stock available after each movement; this is the figure that answers how much is on hand.
Supporting document: invoice, delivery note or purchase order number backing the movement, so it can be traced later.
Notes and person responsible: comments about batches, expiration dates or condition of the merchandise, and the name of whoever recorded the movement.

When the kardex is kept on paper, each product has its own card and balances are calculated by hand or with a calculator. In inventory software these fields come already structured and the balance updates itself with every inflow or outflow, eliminating addition and subtraction errors.

How is the warehouse kardex used in daily operations?

The warehouse kardex is not a document filled out at the end of the month: it is updated with every movement of merchandise, the moment it happens. The most common operations that feed the record are:

Receiving: when merchandise arrives from a supplier, it is checked against the purchase order and the invoice, placed on the rack and recorded as an inflow.
Dispatching: when merchandise is delivered for a sale, to an internal customer or for production, the outflow is recorded immediately.
Transfers: when merchandise moves from one warehouse to another or from one location to another, the movement is noted: total stock does not change, but its location does.
Returns: customer returns come back to the warehouse and are recorded as inflows; returns to suppliers leave the stockroom and are recorded as outflows.

The golden rule is simple: record everything the same day. An outflow that is not noted becomes an invisible shortage that only shows up during the physical count. On the other hand, an up-to-date kardex lets you answer in seconds how many units of any reference remain and whether they are enough for the order that just came in.

Who keeps the warehouse kardex?

The natural person in charge of the warehouse kardex is the warehouse keeper or stockroom supervisor. They are the ones who receive the merchandise, place it on the racks, dispatch it and know it physically, so they are best able to record each movement accurately. In small businesses this role falls on the owner, a manager or the same person who works at the counter, but it must always be clear who is responsible for the record. The best practice is to have a single person responsible for keeping the kardex up to date. When several people move merchandise without telling the person in charge, the record loses value quickly. And when the warehouse keeper is away or changes jobs, a well-kept kardex allows the replacement to take over without losing track of the stock.

The relationship between the warehouse kardex and the physical count

The warehouse kardex says how much should be there; the physical count says how much is actually there. Comparing the two is the basis of inventory verification and warehouse audits. If the count matches the kardex balance, the control system is working well. If it does not, there is a difference to investigate: it could be an unrecorded dispatch, a return that was not noted, a typing error, shrinkage or a loss. When a difference appears, the right approach has three steps: record the adjustment in the kardex so the balance reflects reality, find the cause of the shortage or overage so it does not happen again, and review the recording procedure. It is also wise to run cycle counts by zone or product category during the year and one full count at least once a year. A kardex that is never compared with reality can look very tidy and still be very wrong.

Practical example: movements in a warehouse kardex

Let us see how it works in practice. Suppose the warehouse keeps track of the product "nitrile gloves size M", code GNT-M, located in aisle 2, rack B. The kardex for that item during the first half of a month could look like this:

Date	Movement	In	Out	Balance
01/06	Opening inventory	—	—	50
03/06	Purchase received (invoice 0042)	100	—	150
05/06	Dispatch for sale (delivery note 0118)	—	20	130
08/06	Customer return	2	—	132
10/06	Transfer to secondary warehouse	—	12	120
12/06	Dispatch for internal use	—	3	117
15/06	Adjustment for shrinkage found in count	—	2	115

Each row in the table tells a story: the opening inventory, a purchase that raised the balance to 150, the sales and internal uses that gradually reduced it, a customer return that brought it back up and an adjustment for shrinkage found during the count. If the month-end count shows 115 units on the shelf, the kardex and reality match. If it shows a different figure, the difference is investigated and corrected with its own movement.

Benefits of keeping the warehouse kardex up to date

Keeping the warehouse kardex with discipline brings concrete benefits to any business that handles merchandise:

It prevents surprise shortages: you know how much you have before committing to a sale.
It speeds up dispatching: the warehouse keeper knows exactly where to find each product.
It makes purchasing easier: restocking decisions are made with figures, not gut feeling.
It detects shrinkage and losses on time, instead of discovering them months later.
It brings peace of mind in audits, because every movement has a supporting document and a person responsible.
It provides the basis for reconciling with the accounting kardex at the end of each period.

If you still control your stockroom with paper cards or with Excel formulas that break every time someone deletes a cell, it is worth moving to a tool designed for this: Kardex Tauro records the inflows and outflows of your warehouse, updates the balances automatically and lets you check the stock of every product from any device, following the same logic of the classic kardex but without calculation errors.

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