AI for Excel: Formulas, Analysis, Limits

There are three ways to get AI into Excel today: Microsoft's Copilot is built in, while ChatGPT and Claude come as add-ins, meaning extensions that run in a side panel next to your spreadsheet. All three explain and write formulas, analyse tables and, if you want, change the file themselves. All three vendors explicitly advise you to check the results, so you verify every number you pass on.

I work with Claude every day. My fourteen AI employees run on Claude Team, some also on open models or through the API. The details on features and plans in this article come from the help pages of Microsoft, OpenAI and Anthropic, retrieved on 27 October 2026. I deliberately leave out prices because they change often; each vendor's page shows the current state. All the basics about AI are collected on my AI Basics page.

The three options at a glance

A few terms: you install an add-in once via the "Add-ins" menu in Excel and then sign in with your ChatGPT or Claude account. Copilot in Excel has three ways of working: in edit mode it changes the spreadsheet directly, in plan mode it first proposes a plan for you to confirm, and in chat mode it only answers without changing anything. According to Microsoft, Copilot in Excel can work with models from OpenAI and from Anthropic; choosing the model requires a commercial Copilot subscription or Microsoft 365 Premium.

What AI in Excel does well for beginners

The vendors name similar tasks. For everyday office work in small businesses, four of them are the most useful:

1. Have a formula explained. You have taken over a spreadsheet and do not understand a formula. Ask: "Walk me through how the number in cell F12 is calculated." Claude names the cells it refers to in its answers, and you jump there with one click.
2. Find an error. "Why does cell B45 show #DIV/0!?" (#DIV/0! means division by zero.) OpenAI and Anthropic give exactly this kind of error hunt as an example. The AI traces the formula chain back and suggests a fix.
3. Analyse a table. Copilot shows results as charts, PivotTables, summaries, trends or outliers. A PivotTable is an overview that condenses many rows by category, for example revenue per month and service.
4. Tidy up. Consistent formatting, removing duplicates, standardising labels. ChatGPT for Excel lists this explicitly as a use case.

An example, made up: a hair salon records its daily takings in a spreadsheet with date, service and amount. The owner wants to know which services brought in the most last quarter. She opens Copilot in plan mode and writes: "On a new sheet, create an overview: revenue per service and month for July to September, with a chart. Do not change the original data." She reviews the plan, confirms it and at the end checks one total by hand.

Limits the vendors name themselves

What stands out is how clearly all three point to their own limits.

• Microsoft: Copilot can make mistakes, misinterpret information or produce inaccurate results. It should not be used for decisions in sensitive areas such as finance, law or medicine. Changes you save are visible to everyone with access to the file. Editing only works when Excel's calculation option is set to "Automatic". And according to Microsoft, Copilot was trained on sources predominantly in English and may not perform as well when prompts or data are in other languages.
• OpenAI: Outputs may be incomplete or incorrect. Check formulas, calculations and changed cells before relying on them. For important work, duplicate the file first. Macros and VBA, meaning self-programmed routines in Excel, may not be fully supported.
• Anthropic: Not recommended for final client deliverables without human review, for audit-critical calculations without verification, or for spreadsheets with highly sensitive data without proper controls. According to Anthropic, "data tables" are not supported, which most likely means Excel's What-If "Data Table" feature, and neither are macros and VBA. The add-in does not run on Excel 2016 and 2019 as perpetual licences, on iPad or on Android.

How Copilot and Claude compare at the office beyond Excel is covered in Copilot vs Claude: What Works at the Office.

What to watch out for

• Copy first, then let it work. OpenAI and Anthropic both advise making a copy of the file before larger changes. It takes ten seconds.
• Spot-check by hand. Check at least one total and one row yourself. If they are right, that proves nothing about the rest, but a gross error will stand out.
• Only spreadsheets from trusted sources. Anthropic warns that files from outside can contain hidden instructions that get the AI to hand over or change data. This is called prompt injection. So do not have the AI work on a spreadsheet from an unknown sender.
• Use client data deliberately. With ChatGPT for Excel, according to OpenAI, Microsoft may also be able to read the workbook content, attachments and prompts, and OpenAI may store some logs for 30 days. With Claude for Excel, Anthropic deletes inputs and outputs within 30 days according to its help page, with exceptions. What you can show an AI is covered in AI and Privacy: What the AI Gets to See.
• The decision stays with you. An analysis shows you what is in the numbers. What you do with it is your call.

Frequently asked questions

Is Copilot in Excel free?

Not without a subscription. For individuals, Microsoft requires Microsoft 365 Personal or Family with an AI credits plan, or Microsoft 365 Premium. In a business, according to Microsoft, a business Microsoft 365 subscription that is eligible for Copilot Chat is enough: you then get standard access to Copilot in Excel, even without a Copilot add-on licence. With the add-on licence you get priority access. Without a Microsoft subscription, the easiest free way to AI in Excel is the ChatGPT add-in, which according to OpenAI also runs on the free plan with limited usage.

Which is better for Excel: Copilot, ChatGPT or Claude?

It depends on what you already use. If you have Microsoft 365 with Copilot, there is nothing to install. If you already pay for ChatGPT or Claude, you get the add-in without an extra subscription; usage does count against your plan's limits, and for ChatGPT Business and Enterprise it follows the plan's credits and usage terms. According to the vendors, all three can generate and explain formulas; OpenAI and Anthropic explicitly give error hunting as an example. Try a real task from your day-to-day work with the tool you already have.

Does AI work with older Excel versions?

According to Microsoft, Copilot applies to Excel for Microsoft 365, the subscription version. According to Anthropic, Claude for Excel does not run on Excel 2016 and 2019 as perpetual licences. With an old perpetual version you can still use the regular chat: upload the file and ask questions.

Can the AI write macros for me?

The add-ins struggle with macros. OpenAI writes that macros and VBA may not be fully supported, and Anthropic explicitly excludes them for Claude for Excel. In the regular chat you can have the code of a macro explained or drafted, but you test it yourself, ideally on a copy.

Does this work with Google Sheets too?

According to OpenAI, ChatGPT is also available as an extension for Google Sheets, installed via the Google Workspace Marketplace. Copilot is tied to Microsoft.

Where to go from here

Take a spreadsheet you analyse regularly, make a copy and have a formula in it explained that you did not write yourself. After that, try a small analysis in plan or chat mode. If your documents are texts and PDFs rather than spreadsheets, read Summarize Texts and PDFs with AI first. A finished analysis often turns into a presentation; how to do that with AI is in How to Create a Presentation with AI. How others use AI in their spreadsheets is what we discuss in my community Claude Practitioners.