Can Claude Read Excel Files? XLSX, CSV, Add-in

Yes, Claude can read Excel files. Upload an .xlsx or .csv file to a chat and Claude will open it, analyse it and answer questions about it. The one setting that matters: Anthropic's help center says you must have code execution and file creation turned on to upload XLSX files. It's on by default for Free, Pro and Max accounts, so most people never notice it.

There are four ways to get a spreadsheet in front of Claude, and they behave differently:

Below is how each one works, the file size limits Anthropic publishes, and how to check the numbers Claude gives you.

How to upload an Excel file to Claude chat

Anthropic's file upload guide lists the document types Claude accepts. For spreadsheets, that's CSV and XLSX, with the note on XLSX requiring code execution.

To upload:

1. Click the + button in the lower left of the chat box.
2. Choose Add files or photos and pick your file, or drag it into the chat window.
3. Ask your question in the same message.

If the XLSX upload is refused, check the setting. Per Anthropic's guide to creating and editing files, it lives under Settings > Capabilities on web and desktop, labelled "Code execution and file creation" (or "Create and edit files" in the newer layout). On mobile it's under Settings, then Capabilities. On Team and Enterprise, an owner can switch it off for the whole organisation, so if the toggle is missing, ask your admin.

What about old .xls files?

The upload guide lists XLSX and CSV but doesn't mention the older .xls format. The simplest fix is to open the file in Excel, Google Sheets or Numbers and save it as .xlsx or .csv before uploading.

What Claude does with your spreadsheet

Claude doesn't "look at" a spreadsheet the way you do. With code execution on, it gets a private computing environment and writes code, usually Python, to open the file and work with it. Anthropic's file creation guide says Claude can:

• Run analyses on uploaded data, including CSV and TSV files
• Produce charts and visualisations as image files
• Create new Excel files with working formulas and calculations
• Turn spreadsheet data into a Word report, a PDF or a PowerPoint deck

That's why the useful prompts are specific. Some that work well:

• "Which five products had the biggest month-over-month drop? Show the numbers."
• "Find duplicate customer IDs and list the rows."
• "Build a pivot of revenue by region and quarter, then chart it."
• "Turn this export into a cleaned .xlsx with a summary tab that uses formulas."

What Claude doesn't see

Two limits are easy to miss:

• Embedded images. For non-PDF documents, the upload guide says Claude extracts text only. A chart or logo pasted into a sheet won't be interpreted. If the chart matters, export it as an image and upload it separately, or give Claude the data behind it.
• Formula logic you don't mention. Claude analyses whatever its code pulls out of the file. If a column is formula-driven, say so, and ask Claude to confirm whether it worked from the formulas or the calculated values.

File size limits for spreadsheets

Anthropic's two help articles give different numbers, so here are both as published on October 27, 2026:

Because XLSX uploads depend on code execution, the safer planning number for a spreadsheet is 30MB. A large export that misses that can usually be saved as CSV (often much smaller), split by date range, or trimmed to the columns you need.

File size isn't the only ceiling. Big files and long conversations eat into your plan's usage limits faster. The Free plan works for this, with usage that resets every five hours. Our post on whether Claude is free covers what each plan allows.

Claude for Excel: the add-in

If your work lives in Excel, the add-in is often better than uploading. Claude for Excel puts Claude in a sidebar inside the workbook. Anthropic's Claude for Excel documentation says it's generally available on Pro, Max, Team and Enterprise plans. The Claude for Microsoft 365 product page says the same: generally available on all paid Claude plans. It's not on Free.

What it can do, per Anthropic's docs:

• Answer questions about the open workbook with cell-level citations you can click
• Change assumptions while keeping formula relationships intact
• Trace errors like #REF! and #DIV/0! to their root cause
• Build new models or fill in existing templates across multiple tabs
• Sort, filter, edit pivot tables, apply conditional formatting and add data validation dropdowns

You install it from Microsoft AppSource ("Claude for Microsoft 365") and sign in with your Claude account. It runs on Excel on the web, Excel on Windows with a Microsoft 365 subscription (build 16.0.13127.20296 or later), and Excel on Mac (version 16.46 or later).

Add-in limitations

Anthropic also warns about prompt injection: "Only use Claude for Excel with trusted spreadsheets." A downloaded template or vendor file can hide instructions meant to manipulate the add-in. When Claude proposes a risky operation, it asks you to confirm, so read those prompts properly.

Usage in the add-in counts against the same limits as the rest of your Claude account. For how Claude for Excel compares with Copilot, Gemini in Sheets and others, see our roundup of AI tools for Excel.

Reading spreadsheets with Claude Code

Claude Code works on files on your own computer, which is handy when a spreadsheet is part of a project or too sensitive to upload through a browser. It handles the two formats differently, according to Anthropic's Claude Code tools reference:

• CSV is plain text, so Claude reads it directly. Files over 256KB are read in pages rather than all at once.
• XLSX is a binary format, and the Read tool refuses it. Claude doesn't stop there. The error suggests a skill for the file type if you have one, or a shell command or script that reads the format. In practice, Claude writes a short Python script with a library like pandas or openpyxl.

That second point is worth knowing before you start. The script runs on your machine, so it needs Python and whatever library it imports to be available there. For a quick read of a large workbook, exporting the sheet you need to CSV first is often faster.

Claude Code needs a paid plan or a Console (API) account. The Free plan doesn't include it.

Spreadsheets through the Claude API

Developers can do the same thing in code. The API's code execution tool can process files uploaded through the Files API, and its docs list CSV and Excel (.xlsx, .xls) among them. The sandbox comes with pandas, numpy, openpyxl, xlsxwriter and xlrd pre-installed. The container has no internet access, so Claude can't install anything beyond the pre-installed libraries.

API usage is billed per token, separately from any Claude chat plan.

How to check Claude's spreadsheet answers

Claude is good at spreadsheets and still makes mistakes: a mis-read header, a filter applied to the wrong column, a total that silently skipped blank rows. Anthropic's own add-in docs say not to use it for audit-critical calculations without verification. A few habits catch most errors:

1. Ask for the method. "Show the code you ran" or "list the steps" makes a wrong filter visible.
2. Check row counts first. Ask how many rows and columns Claude loaded. If it doesn't match your file, stop there.
3. Spot-check two or three numbers by hand. Pick one total and one individual row and confirm them in Excel.
4. Prefer formulas over pasted values. When Claude builds a file, ask for formulas so you can audit the logic in the sheet itself.
5. Name the sheet and range. In multi-tab workbooks, say which tab and which columns to use.

The same discipline applies to reports. We cover the PDF equivalent in can Claude read PDFs, including how page limits change what Claude sees.

Where Taku fits

Most spreadsheet wins with AI happen once in a chat and then get lost. Taku is an AI-native desktop workspace where you can save a workflow that worked, such as "clean this export and build the summary tab," and run it again next month on new files instead of re-prompting from scratch. It's in Beta.

FAQ

Can Claude read xlsx files?

Yes. Claude accepts XLSX uploads in chat as long as code execution and file creation is enabled, which it is by default on Free, Pro and Max.

Can Claude read Excel files on the free plan?

Yes. Code execution and file creation is available on the Free plan, so you can upload and analyse spreadsheets. The Claude for Excel add-in itself needs a paid plan.

What's the maximum Excel file size for Claude?

Anthropic's upload guide lists 500MB per file for chat uploads, but its file creation guide gives 30MB per file for uploads and downloads with code execution. Plan on 30MB for spreadsheets.

Can Claude edit an Excel file and give it back?

Yes. In chat, Claude can create or rebuild an .xlsx file with working formulas for you to download. In the Claude for Excel add-in, it edits the open workbook directly and warns before overwriting existing data.

Can Claude run Excel macros or VBA?

No. Anthropic lists macros and VBA operations as unsupported in Claude for Excel.

Does Claude Code read Excel files?

It reads CSV directly. For .xlsx, its Read tool refuses the binary format, and Claude reads the file with a script or a skill instead.