Got a Spreadsheet You Didn't Build? 7 Questions to Ask Copilot Before the Meeting
Bottom line: switch Copilot in Excel to Chat only, then ask it 7 things. What the file is about. Where the trends and outliers are. How the numbers break down. What the comments say. What a formula does. What to ask the person who built it. And how to check the answers.
Chat only guarantees that nothing in the workbook changes, so Copilot can't edit someone else's file.
Say a workbook lands in your inbox an hour before the meeting. Many tabs, someone else's logic, no notes. Welcome to Tuesday. This is how I'd read it with Copilot.
First, switch Copilot in Excel to Chat only
Do this before your first question. Copilot in Excel opens in edit mode by default, and edit mode can change the workbook. So use the mode selector above the message box and pick Chat only. (The 3 options read Allow editing, Plan and Chat only.)
Microsoft's own tutorial says Chat only guarantees that nothing in your workbook changes. Copilot reads your data, analyses it and answers in the pane. That's the right setting for a file you didn't build, and for a file that isn't yours to break.
You need a Copilot licence that covers Excel (see Is Copilot in Excel free?). More habits like this one are in Copilot tips for Excel.
What is this workbook actually about?
Start wide. You want the map before the details: what each sheet holds, what the numbers measure, and over what period.
Summarise this workbook sheet by sheet. For each sheet, tell me what it is for, what the key columns are, and what date range it covers.
What to check: Microsoft doesn't say whether chat mode reads every sheet. So check that the answer mentions each tab. If one is missing, name it and ask again.
What are the main trends and outliers?
This is the use Microsoft documents most clearly. Ask about your data and it can return insights such as summaries, trends and outliers. Microsoft's tip: be specific, and name the columns.
Look at the Revenue and Date columns on the Sales sheet. What are the 3 main trends, and which months are outliers?
What to check: in chat only, the answer stays in the pane and nothing is added to the file. If you want a chart or a PivotTable in the file, that's edit mode. Don't do that on a file that isn't yours.
How do the numbers break down?
Totals hide the story. Ask for the split along the line your meeting will argue about.
Break down total revenue by region and by product. Show the top 5 and the bottom 5 of each, and what share of the total each one is.
What to check: ask which columns it used, then check one number against the sheet yourself. If it can't point to where a figure came from, don't repeat that figure in the meeting.
What are people saying in the comment columns?
Survey answers, support notes, customer feedback. Nobody reads them all. Microsoft documents this one: Copilot can summarise large sets of text and pick out key themes and sentiment. In edit mode it adds the results as a new column. In chat only, it answers in the pane, so nothing lands in the file.
Summarise the comments in column F. Give me the 5 main themes, the overall sentiment, and one example comment for each theme.
What to check: Microsoft says you can hover over the superscript number in a text analysis to see the source data. That's documented for text-analysis results. Whether chat-only answers carry those numbers isn't documented, so read a few raw comments yourself.
What does this formula do?
Every inherited file has a formula nobody dares touch. So ask about it. Select the cell with the formula and ask. Microsoft documents the request, though not for a specific mode, so confirm it answers in chat only. It's a question, not an edit.
Explain the formula in cell D3 in plain English. What does it calculate, and which cells does it depend on?
What to check: pick the 2 or 3 formulas your totals depend on, not all of them. Then compare its explanation with the cells it names.
What should I ask the person who built this?
This one is meeting prep rather than analysis. The goal is to walk in with a sharp question instead of a nod, not to audit the file.
I didn't build this workbook. List 5 questions I should ask its author about the data, the assumptions, and anything that looks hard-coded or inconsistent.
What to check: treat the list as a checklist to confirm, not as findings. Copilot can misread what it sees.
How do I know Copilot's answers are right?
You don't, until you check. Microsoft says plainly that Copilot can make mistakes, misinterpret information or produce inaccurate results, and that you should avoid using it for decisions in sensitive areas such as finance, legal or medical topics. Review and verify before you rely on it.
So use it to get oriented and to prepare questions. Then:
1Spot-check 3 numbers
Any figure you plan to say out loud, find it in the sheet yourself.
2Ask where it looked
Which columns, which sheets. A vague answer is a warning sign.
3Ask the owner
If a decision hangs on it, the person who built the file confirms the number. Copilot doesn't.
What can't Copilot in Excel read? Mostly, Microsoft doesn't say
Here is what I can and can't tell you. Microsoft documents what chat mode does (analyse without changing). It documents almost nothing about what it can't read (which is the part you'd want to know).
1Charts and pictures
Microsoft documents Copilot creating and editing charts. It says nothing about reading an existing chart or an image in a sheet. Don't assume it sees them.
2Hidden and protected sheets
The only rule Microsoft states is about a hidden .Rules worksheet, which Copilot ignores. Nothing on other hidden sheets, and nothing on protected ones.
3Big files
The Excel FAQ, get-started and tips pages state no file size, row or cell limit. One Microsoft accessibility tutorial still mentions a cell limit that contradicts them. Test a big file before you rely on it, and check the answer covers all of it.
4The shape of the data
Structure helps. Microsoft's tutorial says Copilot works best with a table or range with one header row, one kind of thing per column and no merged cells scattered around. When it struggles, it says, the shape of the data is very often the reason.
On a big or unusual file, the check from question 7 is not optional.
Questions about Copilot Excel data analysis
How do I analyse data in Excel with Copilot?
Open the Copilot pane, switch it to Chat only, and ask about your data. Name the columns you care about, because Microsoft says that produces more accurate results. Copilot can return summaries, trends and outliers.
Can Copilot analyse an Excel spreadsheet without changing it?
Yes. In Chat only mode, Microsoft says Copilot analyses your workbook data and gives insights without making changes. Excel opens Copilot in edit mode by default, so switch the mode before you ask.
What is the best Copilot prompt for Excel data analysis?
One that names the sheet and the columns and asks for a specific output, such as the 3 main trends or the top 5 by region. More wording ideas are in Copilot prompts for Excel.
Can Copilot in Excel read charts, images or hidden sheets?
Microsoft doesn't say. It documents Copilot creating charts, not reading existing charts or images, and its only stated hidden-sheet rule is that a hidden .Rules worksheet is ignored. Check that the answer covers what you expect.
Is Copilot's Excel analysis accurate enough for finance decisions?
Not without review. Microsoft says Copilot can make mistakes or misinterpret information, and that you should avoid using it for decisions in sensitive areas such as finance. Use it to get oriented, then verify the numbers.
How do I check where a Copilot answer came from?
For text analysis, Microsoft says to hover over the superscript number to see the source data. For everything else, ask which columns it used and check a few figures against the sheet.
Reading a file you didn't build is a leadership skill.
I run a 90-minute executive briefing for leadership teams. And hands-on Excel workshops for finance teams. Clients include Intel, Roche, EY, Deloitte and Amdocs.