Summarising a table or sheet with AI

What happens when I ask AI for a summary of a table?

You type a question, and the AI reads the data it's pointed at and writes an answer. In Excel, Copilot returns insights as charts, PivotTables, summaries, trends or outliers.¹

You can keep it from touching the file. Microsoft says chat-only mode can analyse your workbook data and provide insights without making changes to your workbook.²

Why can the numbers be wrong?

A few reasons, and the makers' pages point to several.

The question was vague. Microsoft's tip is to be specific and name the columns.¹ "How are we doing?" leaves a lot to guess. "Total of column D by region in column A" doesn't.

The data was messy. A column with numbers stored as text, blank rows or mixed types can trip up any tool. Excel's own PivotTable guide has a good example: if Excel interprets your data as text, the data is displayed as a COUNT instead of a sum.³ The same mess can mislead an AI.

The AI only saw part of it. Google says its AI function doesn't have access to your whole spreadsheet, so you give it a range. It also says using the range argument is highly recommended to improve output quality.⁴

Text, not arithmetic. Google notes responses from the AI function are limited to text.⁴ A total it gives you is generated text, so compare it with a formula such as SUM.

It's a language tool. Google's AI function page warns that the suggestions can be inaccurate or inappropriate.⁴

How do I check a summary?

Use the sources the tool gives you. For summaries of text such as survey comments, Microsoft says to hover over the superscript number in the analysis to see the source data Copilot referenced.¹

For numbers, recompute one or two yourself:

• Add the column with a plain SUM and compare it to the AI's total.
• Build a quick PivotTable on a copy of the data and compare the groups.
• Count the rows, and see that the AI's count matches.

If a figure is out by even a little, don't use the rest without checking it too.

For PivotTables, Microsoft says your data should be organised in columns with a single header row.³ That tidy layout helps AI and humans alike.

Which parts should I trust?

Trust it to point you at something. Don't trust it to be your final number.

Use AI to ask "which region looks odd?" Then confirm that with a formula. Microsoft says Copilot's output needs verifying.¹

If a figure goes into a report, a tax return or a quote, it needs to come from a formula or PivotTable you can repeat. Which jobs fit that rule is sorted out in the exact-figures rules.

If you're not sure what the AI sees, read the basics page.