A report you attach to one conversation is different from reference material you add to an ongoing Project. That distinction explains why you may see both 500 MB and 30 MB quoted as Claude’s file limit.
This guide covers Claude.ai chat and Projects. If you are working with files in a coding workspace, see Claude Code permissions and workspace access. For an overview of the two approaches, read how chat uploads differ from workspace access. The Anthropic Files API has separate rules.
Claude file upload limits at a glance
Anthropic’s file-upload guidance documents the following limits. Check that guidance when preparing a workflow that depends on a particular figure.
| Where or what you are uploading | Documented limit | What it means for your files |
|---|---|---|
| Claude.ai chat | Up to 20 files per chat and 500 MB per file | Extracted content can still reach additional token limits |
| Claude Project files | 30 MB per file; no fixed file-count cap listed | Paid-plan Projects can use retrieval for knowledge larger than a single context window |
| Images | Maximum 8,000 pixels on either dimension | Check both width and height before uploading |
| PDFs | Maximum 1,000 pages, subject to other file limits | The PDF’s total length affects whether its visuals can be processed |
Adding a file to a Project? Use the 30 MB per-file limit, not the 500 MB chat limit.
If you are comparing tools, see Gemini Apps file-upload limits for that product’s figures.
Which file types does Claude support?
Anthropic lists these document formats:
PDF, DOCX, CSV, TXT, HTML, ODT, RTF, EPUB, JSON and XLSX.
Supported image formats are:
JPEG, PNG, GIF and WebP.
XLSX processing requires Claude’s code-execution and file-creation capability. If it is unavailable in your session or plan, XLSX processing may be limited or unavailable.
There is also an important distinction between a document’s text and its pictures: Claude does not read images embedded in non-PDF documents as images. A Word document containing a chart may therefore provide useful text without making the chart itself available for visual interpretation.
If a required format is not listed, check the current upload guidance and interface before converting or preparing a batch.
Can Claude read charts and images inside a PDF?
The answer depends on the length of the whole PDF:
| PDF length | Documented handling |
|---|---|
| Up to 100 pages | Text and visual elements can be processed |
| 101–1,000 pages | Text-only processing throughout the document |
| More than 1,000 pages | Exceeds the PDF page limit |
Consider a 200-page research report with a chart on page 50 and another on page 150. Both are affected by text-only processing. The first chart does not gain visual processing simply because it appears within the first 100 pages.
If a visual is essential to your task, use an authorised excerpt of no more than 100 pages or upload the relevant image separately. The other file and image limits still apply.
Splitting a report creates new files, uses more of the 20-file chat allowance and can separate important context. Keep the labels, definitions and surrounding material needed to understand each excerpt. These distinctions are documented in Anthropic’s file-upload guidance.
What about images inside Word documents?
Images embedded in non-PDF documents are not read as images. If a DOCX or HTML file contains an important chart, screenshot or diagram, extract and upload that visual separately when you are authorised to do so.
Separate image uploads must use a supported image format and be no larger than 8,000 pixels on either dimension. They also need to fit the applicable file limits.
For example, if you want Claude to compare the conclusions in a supplier report with its chart, provide the relevant text and the chart in forms Claude can process. Ask about a specific label or value, then compare the answer with the original. Supported visual processing does not guarantee that every detail will be interpreted correctly.
How Project knowledge differs from one chat’s context
Projects can hold reference material for ongoing work, but stored knowledge and the context used for one answer are different things.
On paid plans, Projects can automatically use retrieval when knowledge approaches the context limit. This allows Claude to select relevant material from a larger collection for a response. It does not put every stored document into every answer. See Anthropic’s Project retrieval guidance.
Chat attachments also have limits beyond their byte size and file count. A file below 500 MB can still contain enough extracted content to reach an additional token limit.
When building project context, organise your questions around the material you need. Name the report or section you want used and verify important facts against it. For a large comparison, work through focused questions or divide the task across chats or Projects where appropriate.
What to check when a Claude upload fails
Start by identifying where you are adding the file: a chat or a Project. Then work through the relevant checks:
- File type. Is it listed as supported? For XLSX, is the required capability available?
- File size. Apply the chat or Project limit for that upload.
- File count. A Claude.ai chat accepts up to 20 files.
- Images and PDFs. Check image dimensions or PDF page count as well as size.
- Extracted-content limits. A file within its size cap may still reach an additional token limit.
If those checks do not explain the failure, consult Anthropic’s current support guidance. Claude Code and API limits do not describe Claude.ai uploads.
Check new versions before they become project context
A client brief, research report or reference document may be updated after you first add it to a project. Check new document versions for prompt-injection signals before using the replacement. An edited or re-exported copy needs its own check too.
For a repeatable approach, .mdSiren is a document security checkpoint for AI projects. It checks each supported exact version and routes it to Approved, Needs review or Quarantine before you add it to Claude yourself. This is not a native Claude integration. Coming soon.
Frequently asked questions
What is the maximum file size in Claude.ai?
500 MB per file in a Claude.ai chat. Files added to a Project have a separate 30 MB per-file limit.
How many files can I add to one chat?
Up to 20 files per Claude.ai chat. That is a chat limit, not a Project file-count limit.
Why do some sources say 30 MB?
30 MB is the current per-file limit for Project files. Check whether a guide is discussing chat attachments or Project knowledge before applying its figure.
Can Claude read a 1,000-page PDF?
A 1,000-page PDF is within the page limit, subject to size and other constraints, but receives text-only processing throughout. Text and visual processing applies to PDFs of up to 100 pages.
Can Claude read images inside a DOCX?
Not as embedded images. If a visual matters to your task, upload it separately in a supported format within the applicable limits.
Does Claude Code use these upload limits?
No. Claude Code works with workspace access, permission rules and sandboxing. See the Claude Code permissions guide for that workflow.
