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Seven patterns for replacing repetitive Excel work with AI
You do not need to move all of your spreadsheet work to AI. Leave what formulas already do well, and hand over only the part a person was eyeballing and judging. Here are the seven patterns that keep coming up in practice.
7 patterns AI vs formula Verification included
The short answer
The most common failure in spreadsheet automation is letting AI do the arithmetic. Formulas are exact and reproducible. What AI is good at is not calculating but organising, classifying and interpreting — the part a person used to do by looking.
The seven below are split along that boundary, and each one states how you verify the result. Automation without a verification step is not automation, it is delegation — and when it is wrong, nobody finds out.
Draw the boundary first — what to hand over, and what never to
| Task | Give it to | Why |
|---|---|---|
| Totals, ratios, deltas | A formula | The result is always the same, and it can be audited |
| Branching on a condition | A formula | IF and VLOOKUP are already exact and fast |
| Classifying free text | AI | It handles variations in wording that no rule set covers |
| Pulling fields out of unstructured documents | AI | The layout changes every time, so no formula can locate anything |
| Summarising what a table means | AI | The output needed is prose, not a number |
| Final amounts and reported figures | A formula (never AI) | A value you cannot walk back has to be reproducible |
The seven patterns
Keeping the order reduces the failures
There is one thing to do before choosing a pattern: write down how many times a month you do the task and how many minutes it takes. Without that number you have no way to judge whether the automation worked, and nothing to put in front of a budget holder.
Scope comes next. Make the first attempt one column, one task. Move a whole sheet at once and finding where it went wrong costs more than the automation saved.
Last is preserving the original. Always write AI output to a new column or a new sheet. Automation that overwrites source values cannot be undone, and what cannot be undone cannot be verified.
Frequently asked questions
Can I use AI inside the spreadsheet itself?
There are AI features built into the spreadsheet tools, and there is sending the file out to an external tool. If company data is involved, the deciding factor is not features but data handling: check first whether what you paste is used for training, and where it is stored.
The results vary slightly each run. Is that usable?
Anything involving judgement — classification, summarisation — will vary. That is why it never touches final figures, and why a human check is attached. Work that must return the same value every time belongs to formulas in the first place.
What about files containing customer data?
That decision comes before the choice of tool. For files holding personal data or commercial terms, confirm the storage location and the retraining position in the contract before uploading. Until that is settled, test on a sample with the identifying fields stripped.
Which pattern should we start with?
Pattern 2, normalising spellings, carries the least risk. The output is a mapping table a person can review at a glance, and it never touches the source.
Start with what to hand over
Decide which task moves first
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