Spreadsheets vs a real system: when to move
Move when more than one person needs the same truth at the same time. Spreadsheets are an excellent thinking tool and a poor system of record. Keep spreadsheets for thinking. Move to a system the moment two people depend on the same numbers.
When should we stop running the business on spreadsheets?
How to decide:
One person is reasoning about a problem. Buy. Nothing is faster. Any process can be modelled in an afternoon without asking anyone's permission.
Two people edit the same sheet. Build. That produces two versions of the truth, and the reconciliation happens in someone's head.
You need to know who changed a number and why. Build. A cell that changed does not say who changed it or why. When a number is wrong, there is no way back.
Invalid entries must be impossible rather than discouraged. Build. Nothing stops an invalid entry, so validation lives in whoever remembers the convention.
Other software needs to read the data. Build. A sheet in someone's drive cannot be read reliably by anything else.
What drives the cost:
Reconciliation time. Concurrency is the first failure: two people editing the same sheet produce two versions of the truth, and the reconciliation happens in someone's head every week.
No history to fall back on. A cell that changed does not say who changed it or why. When a number is wrong, there is no way back, and the cost is the work redone.
The specification is already written. A spreadsheet a team has actually used for a year is the most accurate specification of a process you will ever get, which makes the build cheaper than starting from a conversation.
What people get wrong:
Treating the sheet as wasted work. The sheet is not wasted. It records what people really do rather than what a policy says, and that is the best starting point for a build.
Waiting for the spreadsheet to break. It will not break. It will quietly produce two versions of the truth, and nobody will be able to say which one is right.
Replacing thinking tools too. Keep spreadsheets for thinking. For a single person reasoning about a problem, nothing is faster.
Why do spreadsheets win for so long?
They are free-form, immediate, and everyone can already use one. Any process can be modelled in an afternoon without asking anyone's permission.
Where do spreadsheets quietly fail?
Concurrency, history and rules. Two editors produce two versions of the truth, a changed cell does not say who changed it or why, and nothing stops an invalid entry.
What does a real system add?
One record, one version, an audit trail, and rules that hold whether or not anyone remembers them. Permissions so the right people see the right things, and data other software can read.
Is the spreadsheet work wasted when we move?
No. A spreadsheet a team has used for a year is the most accurate specification of a process you will ever get, because it records what people really do rather than what a policy says.
Last reviewed 22 August 2026