Many businesses start tracking stock in Excel, and that is a good decision. It is fast, familiar and free of project overhead. The trouble is that a spreadsheet that worked for one person and fifty products keeps getting asked to do more, until one day it quietly becomes the most important system in the company without ever being designed as one.
Here are the signs that it is starting to break, and how to tell when it is time to move on.
Two people, one file
The first crack usually appears when a second person needs the same file. Microsoft's own documentation describes the older "Shared Workbook" feature as legacy, with limitations, and points to co-authoring as its replacement. Co-authoring works when the file is stored in OneDrive or SharePoint Online and everyone uses a version of Excel that supports co-authoring.
Even then, Microsoft's guidance on conflicting edits is that, generally, the last change saved wins, and it suggests assigning each person their own areas or sheets to avoid collisions. That is reasonable advice for a shared budget. For stock, it is a problem: if two people update the same quantity at nearly the same time, Microsoft's documented rule is that the last change saved wins, so one update can overwrite the other and the quantity ends up wrong.
Overwriting is the default
In a spreadsheet, typing a new number replaces the old one. There is no built-in notion of "a movement of minus three units because of order 1042". You see only the result. So a count of 40 becomes 37, and unless someone also noted why, nobody can tell whether it was a sale, a breakage, a correction or a slip of the finger.
Excel does offer version history for files stored in the cloud, and you can open a past version. But that is a copy of the whole file at a point in time. It is a way to go back to an earlier copy of the file, which makes version history a recovery tool for emergencies, not a movement-by-movement record of daily operations. Excel's Show Changes feature (for files in OneDrive or SharePoint) can show who changed a cell, when, and the previous value, for a limited period. It does not record why, and it is not a movement ledger with order references, so for stock it is a weak substitute for a real audit trail.
Everyone can change everything
A spreadsheet can be protected by sheet or by file, but day to day it usually comes down to who has the file. The person who receives goods can also change prices. The person who answers customers can also delete a row. That is rarely malicious; it is that nothing stops an honest mistake such as sorting one column without the others, or dragging a formula over the wrong cells. A system can give the warehouse the ability to record movements, sales the ability to see availability, and only managers the ability to correct things.
Selling what you do not have
This is where the cost becomes visible to customers. Stock in a file is a snapshot. If it is saved on someone's laptop, or a copy was emailed on Tuesday, then sales and warehouse are working from different numbers. An order is accepted for something that was already sold an hour ago, and someone has to call the customer to apologize. A system where orders and stock live in the same place reserves the item the moment it is sold, for everyone at once.
Other warning signs
- Only one person really understands the file, and holidays make you nervous.
- Several versions exist, named "final", "final2" and "final-REAL".
- Formulas break when someone inserts a row or sorts the data.
- You spend the first hour of Monday reconciling the weekend's changes.
- You need the numbers on a phone, in the warehouse, or for a customer, and the file does not work there.
- Another tool, such as the website or invoicing, needs the same data, and someone retypes it.
One of these is annoying. Three or four together mean the file has outgrown its job.
What moving to a system actually involves
A common fear is that moving means throwing away the spreadsheet you know. In practice, the spreadsheet is the best specification you have: its columns show what you track, its formulas show your rules, and its history shows your exceptions. A well-planned move usually starts by importing the existing data, rebuilding the screens people actually use (receive, sell, count, adjust), and keeping the export-to-Excel option for the reports that people like to slice themselves. You do not need to replicate every tab on day one.
When to stay with Excel
If one person maintains it, the number of products is small, and a mistake costs little, Excel may be the right tool for years. Moving earlier than needed only adds cost. The signal to move is not the size of the file, but the cost of an error: lost sales, wrong promises to customers, and hours of reconciliation.
A practical first step
For one week, keep a short list of every time the spreadsheet caused a problem: a conflict, a wrong number, a question nobody could answer, a customer disappointed. At the end, add up the time it took to fix each. That list is the honest case for or against a change, and if you decide to move, it is also your first set of requirements.