File Limits in Claude
A beginner-friendly guide to what you can upload to Claude, how big and how many, why chats and projects follow different rules, what PDFs and spreadsheets need, and what to do when a file will not fit.
Imagine posting a parcel. The post office has rules: a maximum weight, a maximum size, and a list of things you are not allowed to send. If you know the rules, the parcel goes through without any fuss. If you do not, you may stand in a queue only to be told the box is too big, or that the item cannot be sent at all. Frustrating, and mostly avoidable.
Uploading files to Claude works in much the same way. Claude can read documents, spreadsheets and images, which makes it a handy helper for real work. But there are limits on file size, file count, page count and how much material Claude can hold in mind at once. This guide explains those limits from scratch. No technical knowledge is needed. Every new word is explained when it first appears, and each big idea comes with an everyday comparison.
File limits change over time, and older articles online often quote older numbers. The figures in this guide reflect what Claude’s help centre described at the time of writing. Before relying on a number for something important, check the current article titled “Upload files to Claude” at support.claude.com.
1Why Does Claude Have File Limits?
Limits can feel annoying, so it helps to understand the reasons behind them.
When you upload a file, Claude does not simply store it like a cloud drive. It reads the contents and makes them available for the conversation. Reading takes computing effort, and holding the contents in view takes space. Two kinds of limit follow from this.
The first kind is about the upload itself: how large a single file may be, and how many files you may attach. These are practical limits on what the system will accept. The second kind is about Claude’s working memory, usually called the context window. This is the total amount of material Claude can consider at one time, including your messages, its replies and the contents of your files. A file can pass the upload check and still be too big to fit comfortably in that working memory.
Upload limit
The rule about how big a file may be and how many files can be attached at once.
Context window
The total amount of material Claude can keep in view at one time, like the size of a working desk.
Token
A small chunk of text, such as a word or part of a word, used to measure how much material there is.
Text extraction
Reading just the written words out of a file, without interpreting pictures or layout.
Think of a lift in a building. There is a limit on how heavy each box may be, and a limit on how many boxes fit in the lift at once. Even if every box passes the weight check, too many together will not fit. File limits and the context window work like those two checks.
Passing the upload is not the same as being fully usable. Always think about both the file’s size and how much text it really contains.
2The Limits at a Glance
Here is the overall picture before we examine each piece.
According to Claude’s help centre at the time of writing, there are two main places to put files. You can attach them to a chat, where they are used for that conversation. Or you can add them to a project, which is a saved workspace that keeps reference material available across many conversations.
| Where | Size per file | Number of files | Other notes |
|---|---|---|---|
| Chat upload | Up to 500MB | Up to 20 files per chat | Images up to 8000 by 8000 pixels |
| Project files | Up to 30MB | No fixed count, but total content must fit in the context window | Text extraction only, except for multimodal PDFs |
| PDFs | Within the limits above | Counts as a file | Over 1000 pages is rejected |
Older help pages and many articles describe a 30MB limit for chat uploads. The current figure for chats is larger. If you see a different number elsewhere, the date of the source probably explains the difference. Trust the current official page.
A chat is like a temporary desk where you spread out papers for one meeting. A project is like a filing cabinet that stays in the room for the whole season. The desk may allow bigger single items for the meeting, while the cabinet has its own rules for what it stores.
3Which File Types Can Claude Read?
Size is only half the story. The kind of file matters too.
Claude’s help centre lists a set of supported document types and a set of supported image types. If a file is not in these families, Claude may not be able to read it.
Text-style files
PDF, DOCX, TXT, HTML, ODT, RTF, EPUB and JSON are among the supported document types.
Tables and data
CSV files are supported, and XLSX spreadsheets are supported when certain features are enabled in your account.
Pictures
JPEG, PNG, GIF and WebP images are supported.
Everything else
Types outside the supported list, such as video and audio files, are not among the documented document or image types.
To upload XLSX files, the help centre says you must enable code execution and file creation in your account. If an Excel file will not upload, check this setting first. Saving a sheet as a CSV is another common route.
flowchart TD
A["Your file"] --> B{"Is it a supported type?"}
B -- "No" --> C["Convert it to a supported type or copy the text"]
B -- "Yes" --> D{"Within the size and count limits?"}
D -- "No" --> E["Split, compress or reduce it"]
D -- "Yes" --> F{"Will the content fit in the context window?"}
F -- "No" --> G["Work in sections"]
F -- "Yes" --> H["Upload and ask your question"]
A library only has shelves for certain kinds of materials. Books, journals and maps are welcome. A live animal is not, however nicely it is boxed. The supported file types are the kinds of materials Claude’s shelves are built for.
4Chat Uploads in Detail
Chat uploads are the quickest way to work with a file, so let us look at them closely.
When you attach files to a chat, they are used for that conversation. You can usually add them in several ways: through the plus button near the message box, by dragging and dropping files into the chat window, or, for images, by pasting from your clipboard. Per the current help centre figures, a chat can hold up to twenty files, each up to 500MB, with images up to 8000 by 8000 pixels.
These are limits on what can be attached. The practical limit is often lower. A very large file may contain more text than can fit in Claude’s working memory, and a conversation also uses some of that space for your messages and Claude’s replies. So the number of files and the amount of text you can usefully discuss at once depends on how long the contents are.
Open a chat
Start a new conversation or continue an existing one.
Attach your files
Use the plus button, drag and drop, or paste an image from your clipboard.
Say what you want done
Add a short instruction, such as summarise, compare or extract.
Check Claude has read it
If anything seems missing, ask Claude to name the document’s title or first heading as a quick test.
Handing papers to a colleague in a meeting is quick and easy. But if you hand over a huge stack, they cannot absorb it all at once, however willing they are. Chat uploads are quick, but the amount Claude can digest in one sitting is still limited.
Large attachments and long conversations use more of your plan’s usage allowance. The help centre lists file attachment size as one of the factors that affects how quickly you reach your limits.
5Project Files in Detail
Projects follow a different set of rules because they are designed for material you will use again and again.
A project is a workspace on paid Claude plans where you can save reference material, such as guidelines, background documents or notes, so it is available across many conversations without uploading again. Files in a project’s knowledge area are limited to 30MB each. The number of files is described as unlimited, but with an important condition: the total content must fit within Claude’s context window. Project files use text extraction only, except for PDFs that Claude can read with their visuals.
So “unlimited” does not mean you can add endless material and expect Claude to use all of it at once. It means there is no fixed count, while the real ceiling is the amount of content Claude can hold in view. Some plans may also use a retrieval feature that helps projects handle more material than would otherwise fit, so it is worth reading the current article on projects at support.claude.com.
Advantages of projects
- Upload reference material once and reuse it across chats
- No fixed cap on the number of files
- Good for guidelines, background papers and ongoing work
- Keeps related conversations organised in one place
Things to watch
- Smaller per-file size than chat uploads
- Total content still limited by the context window
- Text extraction only for most file types
- Available on paid plans
flowchart LR
A["Chat upload"] --> B["Used for one conversation"]
C["Project file"] --> D["Available in every chat in the project"]
B --> E["Larger single files, up to 20 per chat"]
D --> F["Many files, each up to 30MB, total must fit"]
A bookshelf can hold many books, but the number you can open on your desk at once is small. A project is the bookshelf, and the context window is the desk. You can own plenty of books, yet only so many fit in front of you at the same time.
6PDFs: Pages and Pictures
PDFs are the most common upload, and they have a few special rules of their own.
For PDFs, the number of pages matters as much as the file size. Claude’s help centre describes two key thresholds. PDFs of up to 100 pages can be read with their visual elements, such as charts, images and diagrams, as well as their text, when used with supported models. PDFs longer than 100 pages are read as text only, so pictures and charts are not interpreted. And PDFs over 1000 pages cannot be uploaded at all. If you try, you will see an error saying the file is too large.
| PDF length | What Claude reads |
|---|---|
| Up to 100 pages | Text and visual elements, such as charts and diagrams, with supported models |
| 101 to 1000 pages | Text only, without interpreting images or charts |
| Over 1000 pages | Not accepted, and an error appears |
Page numbers
When you refer to a particular page, use the page number shown by your PDF viewer, not the number printed on the page itself, since these can differ.
Scanned PDFs
If the text in a PDF is not properly formatted or legible, Claude may have trouble reading it. A clean, text-based PDF generally works best.
Charts in long reports
If a long report has important charts, consider splitting out the pages with charts into a shorter PDF so Claude can read the visuals as well.
flowchart TD
A["PDF"] --> B{"How many pages?"}
B -- "100 or fewer" --> C["Text and visuals can be read"]
B -- "101 to 1000" --> D["Text only"]
B -- "Over 1000" --> E["Rejected: file too large"]
A short picture book can be enjoyed with both words and illustrations. A very long novel is usually all words. A shelf-breaking encyclopedia may not fit on the bus at all. PDF page limits work in a similar way.
7Images: Size and Quality
Images have their own rules, and quality matters as much as size.
Claude can read images in the JPEG, PNG, GIF and WebP formats. According to the help centre, image dimensions can be up to 8000 by 8000 pixels. For best results, Claude’s guidance suggests using images that are at least about 1000 by 1000 pixels, and avoiding very small or low-resolution pictures, because details are harder to read when an image is tiny or blurry.
Use clear images
Sharp, well-lit pictures are easier to read than blurry or dark ones.
Avoid tiny images
Very small, low-resolution images lose detail, especially small text in screenshots.
Crop to what matters
If only part of an image is relevant, crop it so Claude focuses on the right area.
Paste directly
You can copy an image and paste it from your clipboard into the chat.
Showing a friend a tiny blurry photo on a far-away screen makes it hard for them to see anything. A clear, close picture lets them point out details. Image quality works the same way for Claude.
If an image of a document is hard to read, try retaking it in better light or exporting a screenshot at a higher resolution rather than uploading a small thumbnail.
8Documents, Spreadsheets and Embedded Pictures
Not every file is read in the same way, and the difference can surprise people.
For documents that are not PDFs, such as Word files or text files, Claude extracts the text. This means that if a Word document contains diagrams, photos or charts, Claude reads the words but cannot interpret those embedded images. If the pictures matter, you can paste them separately as images, or export the document as a PDF if that preserves them in a form Claude can read.
Spreadsheets deserve special care. A simple CSV file is just plain text with commas between values, which is easy to read. An XLSX workbook can contain several sheets, formulas and formatting. If a workbook has many sheets, converting the sheet you need into a CSV can make the contents simpler and reduce unnecessary material.
| File | How Claude reads it | Watch out for |
|---|---|---|
| DOCX, TXT, HTML, RTF, ODT, EPUB, JSON | Text extraction | Embedded images are not interpreted |
| Text, and visuals for PDFs of up to 100 pages | Page count thresholds | |
| CSV | Plain text values | Very large tables use a lot of space |
| XLSX | Spreadsheet analysis when the needed features are enabled | Setting must be turned on in your account |
| Images | Visual reading | Quality and resolution affect results |
Imagine a reader who can read printed words perfectly but cannot see the photos in a magazine unless you hold them up separately. For most non-PDF documents, Claude is that reader. If a photo matters, hold it up by sharing it as an image.
After uploading a spreadsheet or a document with tables, ask Claude to describe what it sees, such as the column names or the number of rows. This quickly reveals whether the file was read as expected.
9The Context Window: The Real Ceiling
This is the idea that explains most surprises with large files.
The context window is the amount of material Claude can hold in view during a conversation. It is measured in tokens, which are small chunks of text. Everything counts against it: your messages, Claude’s replies, instructions behind the scenes and the text from your files. Different Claude models and different plans can have different context window sizes, so there is no single number that applies everywhere.
This is why a very large file can upload successfully and still cause trouble. The upload limit says the file is acceptable to send. The context window decides how much of its text can actually be used at once. If the text is too long, Claude may be unable to use all of it, or the conversation may run into length limits sooner than expected.
flowchart LR
A["Your messages"] --> E["Context window"]
B["Claude's replies"] --> E
C["Text from your files"] --> E
D["Background instructions"] --> E
E --> F["What Claude can use right now"]
The upload check
The system checks type, size and count. Passing means the file is accepted.
The reading step
Text is pulled out of the file and turned into tokens.
The fit check
The tokens must fit in the context window together with the rest of the conversation.
A guest may be allowed into a hall at the door, but the hall still has only so many seats. Passing the door check is the upload limit. Finding a seat is the context window.
10What To Do When a File Will Not Fit
Most limit problems have simple, practical fixes.
Split the file into sections
Divide a long document into chapters or topics and upload them one at a time, or work through them in separate steps. Claude’s own guidance recommends dividing larger documents into smaller sections to stay within limits.
Upload only the relevant pages
If you only need part of a document, extract just those pages into a new file. This saves space and keeps Claude focused.
Convert to a simpler format
Save a spreadsheet sheet as a CSV, or copy text into a plain text file, so there is less overhead.
Compress or resize images
Reduce very large images to a reasonable resolution, while keeping them clear enough to read.
Paste the key text
When only a few paragraphs matter, pasting them directly into the chat can be easier than uploading a whole file.
Summarise in stages
Ask Claude to summarise each section separately, then combine those summaries, and return to the original for details that matter.
Use a project for reusable material
If you will refer to the same documents often, add them to a project so you do not have to upload them in every chat.
flowchart TD
A["File will not upload or fit"] --> B{"What is the problem?"}
B -- "Too large" --> C["Split, trim pages or compress"]
B -- "Wrong type" --> D["Convert to a supported format"]
B -- "Too much text" --> E["Work in sections and summarise in stages"]
B -- "Reused often" --> F["Add to a project"]
When a sofa will not fit through the door, you do not give up on the sofa. You take off the legs, turn it sideways or find another route. Large files usually need the same practical thinking.
11Reading Error Messages
When an upload fails, the message and a short checklist usually point to the cause.
| What you see | Likely cause | What to try |
|---|---|---|
| “Uploaded file is too large” | File exceeds a size or page limit, such as a PDF over 1000 pages | Split the file or upload only the relevant part |
| File will not attach at all | Unsupported type, or a limit such as 20 files already reached | Convert the type, or remove some files first |
| Spreadsheet upload fails | The required account setting for XLSX is off | Check the setting, or save the sheet as a CSV |
| Claude seems to ignore part of a document | Content too long for the context window, or text could not be read | Work in sections and ask Claude to describe what it can see |
| Charts in a PDF are not discussed | PDF is over 100 pages, so only text is read | Share the chart pages in a shorter PDF or as images |
| Conversation ends sooner than expected | Large attachments and long chats use more of the available space and allowance | Start a new chat with a short summary, and use fewer or smaller files |
If an upload fails with no clear message, try a small supported file in a fresh chat. If that works, the problem is likely with the first file. If not, check your connection and the service status.
A car’s warning light does not fix anything by itself, but it tells you where to look. Error messages work the same way: read them, think about the likely cause and then apply the matching fix.
12Privacy and Sensible Sharing
The fact that Claude can accept a file does not mean every file should be shared.
Documents often contain personal details, confidential business information or other sensitive material. Before uploading, think about whether Claude really needs all of it. You can often remove unrelated pages or replace real names and numbers with neutral labels, and still get a useful result.
If you use Claude through your workplace, follow your organisation’s rules about what may be shared with AI tools. How files and conversations are handled can differ between products and plans, so read the privacy information that applies to yours.
Share only what is needed
Trim pages or sections that contain unrelated sensitive details.
Replace identifiers
Swap real names, numbers and addresses for neutral labels where possible.
Follow workplace rules
Respect your organisation’s policies on confidential material.
Check privacy settings
Understand how your product treats uploaded files and conversations.
Before photocopying a document for someone, you might cover the private lines. Preparing a file before uploading is the same careful step.
13Common Mistakes with File Limits
These errors appear often, and each has an easy fix.
Problem
Assuming that because a file uploaded, Claude has used all of its content.
Why It’s Harmful
The upload limit and the context window are different. Long content may not all be usable at once, so answers may miss parts of the file.
Correct Approach
Ask Claude what it can see, work in sections for long files, and return to the original for critical details.
Problem
Relying on an old article for limits that have since changed.
Why It’s Harmful
You may plan around a wrong number, for example an older smaller chat limit, and make poor decisions.
Correct Approach
Check the current help centre article before depending on a figure for important work.
Problem
Expecting Claude to read pictures inside Word or other non-PDF documents.
Why It’s Harmful
Only the text is extracted from these files, so important diagrams are silently ignored.
Correct Approach
Share important images separately or use a PDF where visuals can be read.
Problem
Uploading a huge, unfocused file when only a small part is relevant.
Why It’s Harmful
It wastes space and usage allowance, and the important section may get less attention.
Correct Approach
Upload only the relevant pages or paste the key text, and say clearly what you want done.
Problem
Treating “unlimited files” in projects as unlimited capacity.
Why It’s Harmful
The file count has no fixed cap, but total content must still fit in the context window, so excess material may not be fully used.
Correct Approach
Keep project material focused and relevant, and remove outdated files.
Problem
Uploading sensitive files without thinking.
Why It’s Harmful
It creates unnecessary privacy risk and may break workplace policies.
Correct Approach
Remove or replace sensitive details when they are not needed, and follow your organisation’s rules.
14Benefits and Trade-offs
Understanding the limits lets you use file features well.
Advantages of file uploads
- Claude works from your real material, not guesses
- Many common document, data and image types are supported
- Chats accept sizeable files and several at once
- Projects keep reference material ready for repeated use
- Long documents can be summarised and queried quickly
Disadvantages / Trade-offs
- Size, count and page limits apply
- The context window caps how much can be used at once
- Non-PDF documents lose embedded images
- Large files use more of your usage allowance
- Limits can change, so older information may be outdated
A well-organised traveller knows the airline’s baggage rules and packs accordingly. Knowing Claude’s file limits lets you prepare your files so nothing is left at the gate.
15Frequently Asked Questions
According to the help centre at the time of writing, up to 20 files per chat. Projects have no fixed file count, but the total content must fit within Claude’s context window.
The current help centre figures describe up to 500MB per file for chat uploads and up to 30MB per file for project files. Older sources mention 30MB for chats, so check the current article for the latest numbers.
Documents such as PDF, DOCX, CSV, TXT, HTML, ODT, RTF, EPUB and JSON, XLSX spreadsheets when certain account features are enabled, and images in JPEG, PNG, GIF and WebP formats.
The help centre says XLSX files need code execution and file creation to be enabled in your account. You can also try saving the sheet as a CSV.
Yes. PDFs of up to 100 pages can have their visuals read as well as their text with supported models. Longer PDFs are read as text only, and PDFs over 1000 pages are rejected as too large.
No. For non-PDF documents, Claude extracts the text only, so embedded images are not interpreted. Share important images separately.
It is the amount of material Claude can hold in view at once, shared between your messages, its replies and your files. A file can pass the upload check but still contain too much text to use fully.
Split it into smaller sections, upload only the relevant pages, summarise in stages, or paste key passages. Claude’s guidance recommends dividing larger files into smaller sections.
Yes. The help centre lists attachment size among factors that affect usage limits, so large files and long conversations can use your allowance more quickly.
The “Upload files to Claude” article at support.claude.com is the best source. Developers building their own tools on Claude can find separate limits in the documentation at docs.claude.com.
16Summary and Key Takeaways
Claude’s file limits come in two layers. The first layer is about the upload itself: which file types are supported, how large each file may be and how many files can be attached. At the time of writing, chats accept up to twenty files of up to 500MB each, projects accept files of up to 30MB each with no fixed count, and images can be up to 8000 by 8000 pixels. PDFs add page rules: visuals can be read in PDFs of up to 100 pages, longer ones are read as text only, and those over 1000 pages are rejected. The second layer is the context window, the shared working space that decides how much material Claude can actually use at one time. Most problems come from that second layer, which is why splitting, trimming, converting and summarising in stages are the standard fixes. Since limits change, check the current help centre article before depending on a number, and share only the material your task needs.
Key Takeaways
- Two kinds of limit — the upload rules (type, size, count) and the context window, which decides how much content Claude can use at once.
- Chats and projects differ — chats allow up to 20 files of up to 500MB each, while projects allow files up to 30MB with no fixed count but a context window ceiling.
- PDFs have page rules — visuals are read up to 100 pages, text only from 101 to 1000 pages, and files over 1000 pages are rejected.
- File type matters — non-PDF documents give text only, spreadsheets need a setting for XLSX, and images work best when clear and not tiny.
- Passing upload is not the same as fitting — a large file may be accepted yet hold more text than Claude can use at once.
- Use practical fixes — split files, upload only relevant pages, convert formats, compress images and summarise in stages.
- Verify numbers and protect privacy — limits change, so check support.claude.com, and share only what your task needs.