When your spreadsheet should become an app

Excel is the most successful business software ever made, and most companies should keep using it. But somewhere between a handy list and the system that runs your operations, a spreadsheet stops being a tool and starts being a risk. Here is how to tell.

• Only one or two people dare to change it. If the file has a guardian, it has a single point of failure.
• More than three people edit it at the same time, and you regularly find conflicting copies called "final_v7_JK".
• You copy data into it from other systems every day or every week.
• Errors have cost real money: a wrong price, a missed invoice, a double order.
• Customers or suppliers need to see part of the data, and you send them screenshots or exports.
• It takes more than a few seconds to open, or it crashes on a normal laptop.

One sign is normal. Three or more means it is worth looking at alternatives.

Before you build an app, check whether a smaller step solves most of the pain.

Most spreadsheet pain is not the spreadsheet itself but the copy-paste work that feeds it. A small pipeline in Python or Power Automate that pulls exports, cleans them and fills the sheet can save hours per week, often for a few thousand euros.

Data validation, locked cells and a simple check tab that turns red when totals do not match catch a surprising number of errors. It is not glamorous, but it works.

A workbook with 40 tabs usually contains three or four separate processes. Splitting them makes each one simpler and reduces who needs to touch what.

If you have done the above and still see the signs, it is time for a proper application. The typical triggers are multiple users with different rights, external people who need access, and data that has to be connected to other systems in real time.

A good app project starts from the spreadsheet, not from a blank page. The columns tell you the data model, the formulas tell you the business rules, and the colour codes people use tell you what the workflow really looks like.

In our experience, automating the input of an existing spreadsheet starts around 2,500 euros. A small internal web app that replaces a critical workbook, with login, roles and an export back to Excel, usually lands between 12,000 and 25,000 euros.

Count how many hours per week your team spends feeding, fixing and checking the file. Multiply by an hourly cost and by 46 working weeks. If that number is higher than the cost of the fix, you already have your business case. Our hours-saved calculator in the Lab does this sum for you.