Excel and AI: formulas, sales data, Copilot and Gemini

Excel and AI: why the combination works

Almost every small business has a spreadsheet somewhere: sales figures, hours worked, a stock list, a customer register or a budget. Spreadsheets are powerful, but many people find formulas hard and error messages harder. AI acts like a patient colleague who knows Excel and explains things without making you feel stupid.

There are three ways to use AI with spreadsheets:

• Ask a general assistant. Tell ChatGPT, Claude or Gemini what you want to calculate and get a ready formula with an explanation.
• Upload the file for analysis. Most assistants can read Excel and CSV files, calculate summaries and draw charts.
• Use the spreadsheet's built-in AI. In Excel that is Copilot; in Google Sheets it is Gemini.

Formulas written and explained

The easiest place to start is asking for a formula. Tell the AI which columns hold the data and what result you want. The more precisely you describe your sheet, the more likely the formula works first time.

Excel translates function names into the program's language, and Finnish and Swedish versions usually use semicolons as separators. If a formula does not work, the reason is often that the AI gave you the English version while your Excel is in Finnish or Swedish. Ask for the localised version.

AI is also good at explaining formulas someone else built. Paste a long formula you do not understand and ask for a step-by-step explanation. The same works for error messages such as #N/A, #VALUE! or #REF!.

Analysing sales data

The big win comes when you let AI look at your data and ask questions in plain language: which services sell best, which month was weakest, which customers buy most often, how this year compares with last year. You can do this by uploading the file to an assistant or by using Copilot or Gemini directly in the spreadsheet.

AI can also tidy messy data: merge customers entered under slightly different names, fix date formats, remove duplicate rows or split one column into two. This is often the most time-consuming spreadsheet work, and it is where hours are easily saved.

Copilot in Excel

Microsoft's Copilot is built into Excel. Whether you have it depends on your Microsoft 365 plan: for businesses it is usually a separate add-on licence, and some consumer plans include lighter Copilot features. Check the current details for your own subscription.

With Copilot you can, for example:

• ask for a formula for a new column by describing what you want to calculate
• highlight outliers or the largest amounts
• create a pivot table and chart just by asking
• ask questions about the sheet, such as "which customer brought in the most sales in autumn?"

Copilot works best when the data is formatted as an Excel table (Insert > Table) with clear column headings. Merged cells and blank rows confuse it.

Gemini in Google Sheets

If your business uses Google Workspace, Gemini is also available in Google Sheets, depending on your plan. It works much like Copilot: in the side panel you can ask for formulas, summaries, charts and table templates. For example, "create a project tracker with task, owner, due date and status" gives you a ready skeleton to edit.

For a small business, the choice between Copilot and Gemini usually comes down to which office suite you already use. It is not worth switching suites for the AI alone.

Ready-made templates for everyday business

Many owners do the same calculations by hand over and over. AI builds you a ready template in minutes once you say what you want to track, such as monthly cash flow, hours per customer or site, a stock list with reorder alerts, or a pricing calculator with materials, hours, margin and VAT.

A template is only as good as the numbers you put in. Keep forecasts cautious and update actual figures once a month.

Checking the results: do not trust blindly

AI makes mistakes with spreadsheets. It can misread a column, skip rows, mix up amounts with and without VAT, or invent an explanation the data does not support. The answer still looks confident. That is why checking is part of the job.

1. Check the total. Work out one figure yourself, such as the full-year sales, and compare.
2. Ask to see the method. Ask which rows and columns were used.
3. Spot-check. Pick three random rows and make sure they were handled correctly.
4. Separate facts from interpretation. "Sales fell in November" is a fact. "Because the weather was bad" is a guess.
5. Keep the original. Always make changes in a copy, never in the original file.

Decisions such as pricing, hiring or investments should not rest on an AI analysis alone. Use it to find the right questions and discuss important matters with your accountant or another expert. See also AI for small business and presentations and documents.