Using the Claude app, questions about features come up a lot: "Why won't this file upload?", "How much of a PDF does it read?", "How many files in a project?" Rather than login/connection problems (covered separately), this guide answers common FAQs about file upload and document handling, based on the official Help Center. (As of June 2026; source: Anthropic's official "What kinds of documents can I upload to Claude".)
Which document formats can you upload
Per the official Help Center, Claude supports these formats in chats and project knowledge bases: PDF, DOCX, CSV, TXT, HTML, ODT, RTF, EPUB, JSON, XLSX.
One condition: to upload XLSX (Excel) files, you must enable either the analysis tool or Upgraded file creation and analysis in your account. Without it, XLSX upload may be blocked.
What are the file count and size limits
Limits depend on where you upload.
- Chat uploads: 30MB per file, up to 20 files per chat.
- Project knowledge bases: 30MB per file; unlimited number, but the total content must fit within Claude's context window. Except for multimodal PDFs, only text is extracted.
Crucially, even within size/count limits, an additional token limit applies based on the length of extracted content. So even "under 30MB," very long content may only be partially used. Images are supported up to 8000×8000 pixels.
How much of a PDF does Claude read
PDF handling splits by page count. Under 100 pages, Claude analyzes visual elements (charts, tables, images) along with text. Over 1000 pages, it processes text only.
The official docs also give practical tips: when referring to a page, use the page number shown in your PDF viewer, not the printed page number. Use images that are 1000×1000 pixels or larger and avoid small/low-resolution images. For large documents, splitting them into smaller sections reduces limit issues.
If upload fails — a checklist
If a file won't upload or seems only partially used, check these in order:
- Is the file under 30MB?
- Are there no more than 20 files in this chat?
- Is it a supported format (PDF/DOCX/CSV/TXT/HTML/ODT/RTF/EPUB/JSON/XLSX)?
- For XLSX, is the analysis tool / file creation & analysis enabled?
- Is the content long enough to hit the context limit (then only part may be used)?
- Did you split very large documents into smaller pieces?
Note: These limits (30MB, 20 files, etc.) are the values stated in the official Help Center, with an additional token limit based on extracted-content length. Plans, features, and exact numbers may change — check the official Help Center for the latest.
Related reading
Login/response problems: when Claude isn't working; reducing made-up links/content: 6 ways to reduce hallucinations.
Disclaimer: This article is based on Anthropic's official Help Center (accessed June 2026). This site is not affiliated with Anthropic; screens, features, and limits may change with updates.