Compress PDF
Reduce PDF file size so it fits an email or uploads faster. You see the exact saving before you download.
Compression runs on our server, so your files are uploaded. Each one is deleted as soon as your download finishes, and nothing is stored.
How to compress a PDF
Most oversized PDFs are large because of the images inside them. Compression re-encodes those at a sensible resolution and strips out data nothing is using. If you have been looking up how to compress PDF file size without buying software, this is the whole process.
- 1
Add your PDFs
Drag files in or click to browse. Add several at a time if you have a batch to get through.
- 2
Compress PDF files
Press Compress and each file is processed in turn. The saving for every file is shown as it finishes.
- 3
Download what helped
Take the files individually or grab the whole batch as a ZIP. If a file did not shrink, just keep your original.
When a file is simply too big
Usually a limit somewhere is the reason you are here.
Email attachment limits
Get a document under the cap most mail providers enforce so it actually sends.
Upload forms
Meet the size limit on an application or government portal that rejects large files.
Scanned documents
Compress a PDF document saved at far higher resolution than it needs for reading on screen.
Sharing by message
Send a document through a chat app that struggles with large attachments.
Website downloads
Publish a brochure or guide that will not take an age to download.
Saving storage
Reduce a large archive of documents you need to keep but rarely open.
Slow connections
Compress PDF files before uploading over mobile data or a poor hotel connection.
Batch housekeeping
Run a folder of scans through in one go instead of opening each in an editor.
Where the size in a PDF actually comes from
People are often surprised that a ten-page document can be forty megabytes while a two-hundred-page one is under a megabyte. The page count has almost nothing to do with it.
How to compress a PDF here
Upload the file and press Compress. You see the original size, the new size and exactly how much came off before you download anything. It is free to compress PDF documents with no sign-up and no watermark.
This is one of the few tools here that uploads, because the image re-encoding involved needs software a browser cannot run. Your file is deleted from the server the moment your download finishes.
Text is tiny, images are not
A page of text is a few kilobytes. The characters are stored as instructions to draw glyphs from an embedded font, and the font is stored once no matter how many times it is used.
A scanned page is a photograph. At 600 dots per inch an A4 sheet is roughly 35 million pixels, and storing that losslessly runs to several megabytes for a single page. Ten scanned pages can easily outweigh a thousand typed ones, which is why compress PDF file size searches are overwhelmingly about scans.
What compression removes
Images are downsampled to a resolution suited to screen reading and re-encoded, which is where nearly all the saving comes from.
Beyond that, a PDF accumulates material nothing references: fonts embedded in full when only a dozen characters are used, duplicated image streams from a merge, orphaned objects left behind by editing, and metadata from whatever produced the file. All of it goes.
What survives untouched is the text. Compression does not rewrite words or reflow paragraphs, so a text-heavy document comes out looking identical and barely smaller.
When the file gets bigger
It happens, and it surprises people. A PDF that has already been optimised, or one built entirely from vector graphics, can come back marginally larger because the re-encoding adds structure without finding anything to remove.
The result is shown either way, so you can simply keep your original when compression did not help.
The phrasing people use
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And because desktop editors charge for this, the free and online variants dominate: compress PDF online, online compress PDF, compress PDF free, free compress PDF, compress PDF free online, compress PDF online free, compress PDF document online, compress PDF document free, compress PDF file online free. Every one of them is this page.
What to try when it is still too big
Split the document. Two emails of ten pages each get through where one of twenty does not, and Organize PDF handles the split.
Check whether you need every page at all. Cover sheets, blank duplex backs and internal appendices often account for more than compression saves.
If the document is a scan that only needs to be readable, converting it to text with Image to Text produces something a fraction of the size.
Getting the best trade-off
Compression trades detail for size. Knowing where the size actually comes from helps you decide.
- Image-heavy PDFs shrink the most. Scans and photo brochures often drop dramatically, while text-only files barely move.
- Check the result before you use it, especially if the document contains small print inside a photographed page.
- Keep your original. The compressed file is a separate download, so nothing is overwritten.
- If the file barely shrank, its size is probably not coming from images and there is little left to remove.
- Merging first then compressing once is quicker than compressing several files and merging afterwards.
- For a document you will print at full size, consider whether you need compression at all, since the detail loss shows up more on paper.
Questions, answered
What compression does to your file and where it goes.
Upload the file and press Compress. You see the original size, the new size and exactly how much came off before you download. No account and no watermark.
Related tools
Other things you can do here without signing up.