Claude AI Spreadsheet Reading: formats, limits, features, etc

Claude AI supports spreadsheet reading through direct uploads, connected sources, and knowledge bases in Projects. Users can analyze CSV, TSV, and XLSX files, run code-based transformations, and create editable Excel workbooks with live formulas. In late 2025, Anthropic has clarified supported formats, size limits, and context capacities, making spreadsheet workflows more practical across consumer, enterprise, and developer contexts.

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Supported spreadsheet formats.

Claude AI natively supports CSV and TSV uploads in chats. To upload and analyze XLSX files, users must enable the Analysis tool or the Upgraded file creation and analysis feature in Claude.ai. Once enabled, XLSX spreadsheets are parsed like simpler formats, allowing structured analysis.

In Projects, users can add CSV, TSV, and XLSX files directly into a knowledge base. Projects then use Claude’s retrieval-augmented generation to surface only the most relevant content within the context window, expanding practical capacity beyond direct upload limits. Connected Google Drive integrations further extend spreadsheet support, allowing Claude to access Sheets stored in cloud folders.

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File size limits and upload capacity.

Spreadsheet uploads in Claude AI are subject to a 30 MB per file limit. This applies to both uploads in chats and downloads when Claude generates spreadsheets. In chats, users can upload up to 20 files per conversation. In Projects, there is no limit on the number of stored files, but all usable content must fit within the model’s context window, or be filtered through RAG.

For large data tables, CSV or TSV formats are generally preferred because they are lighter and more stable. Very wide or multi-sheet XLSX workbooks may approach the 30 MB cap quickly, and breaking them into smaller files is recommended.

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Context windows and project capacity.

Claude AI’s ability to process spreadsheets depends on model context windows. By default, Claude models handle up to 200,000 tokens, which covers medium to large datasets. Enterprise users of Claude Sonnet 4 can access 500,000 tokens in-app, and through the API, context extends to 1 million tokens.

Projects use retrieval-augmented generation to bypass raw context size. When multiple spreadsheets are stored, Claude retrieves only the most relevant slices rather than loading all data at once. This makes Projects effective for managing very large or numerous spreadsheets while staying within the window size.

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How Claude processes spreadsheets.

With the Analysis tool enabled, Claude can parse spreadsheet tables, execute transformations, and generate visualizations. Internally, Claude uses JavaScript execution to process data dynamically. This enables operations such as pivot tables, sorting, filtering, statistical summaries, and graph creation.

Beyond analysis, Claude can create and edit Excel (.xlsx) files with working formulas, formatting, and multiple sheets. Generated files open directly in Excel and remain fully editable. A common workflow is uploading a CSV, asking Claude to structure it into an organized workbook with formulas, and downloading the resulting file.

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Practical behaviors and restrictions.

If XLSX uploads fail, the first step is to verify that the Analysis tool or upgraded file creation feature is enabled. Without this, XLSX support may be restricted.

Performance degrades when files approach the 30 MB cap or when prompts attempt to load extremely wide or long spreadsheets into the context at once. Splitting large sheets into smaller CSVs and referencing them individually produces better results.

In chats, the 20-file upload limit must be observed. In Projects, while there is no file count limit, retrieval capacity and context still define practical boundaries. Naming sheets and referencing column ranges explicitly improves Claude’s precision when handling complex workbooks.

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Table of spreadsheet reading limits.

Feature	Capacity	Notes
File formats	CSV, TSV, XLSX (with Analysis enabled)	Google Sheets via Drive connection
Max file size	30 MB per file	Applies to uploads and downloads
Files per chat	20	In Claude.ai conversations
Files in Projects	Unlimited storage	Context constrained, RAG expands capacity
Default context	200k tokens	Across consumer plans
Enterprise context	500k tokens in Sonnet 4	1M via API
Processing	JavaScript-based analysis	Code for tables, formulas, and plots
Output	Editable XLSX	Formulas, formatting, multiple sheets

This table outlines the supported formats, upload rules, and processing features that govern Claude’s spreadsheet capabilities.

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Operational considerations.

For best use of spreadsheet reading in Claude AI, users should prefer CSV or TSV formats for large datasets, keeping XLSX files under the 30 MB limit. Enabling the Analysis tool is essential for handling native Excel workbooks. For large or multi-file scenarios, Projects are the better option, since retrieval automatically narrows context to the most relevant sections.

When working with sensitive or high-volume data, enterprises benefit from the expanded context windows of Sonnet 4 and from RAG in Projects. Users who need output for ongoing work can rely on Claude’s ability to generate complete, formula-driven Excel files ready for direct use. These capabilities position Claude AI as a strong assistant for spreadsheet analysis and generation, balancing file limits with robust processing and retrieval tools.

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