Compress PDF

Drop in a PDF and get a smaller one back. The images are resampled to a sensible resolution and the text is left alone, so it stays selectable.

Hybrid processingPDFWorkingNo account needed

What this tool does

Compress PDF does two things to your document. First it rebuilds the file structure losslessly: streams that arrived uncompressed are compressed, objects are packed together, anything nothing refers to any more is dropped and embedded page thumbnails are removed. Then it goes after the part that is usually most of the file, which is the pictures. Each image is resampled down to about 150 dpi (never enlarged) and re-encoded as JPEG at quality 70, and the resolution is worked out from the size the image is actually drawn at on the page, not from the size of the page.

That distinction is what makes it useful on real documents. A camera photo of 4000 pixels placed three inches wide on a page is holding more than 1,000 pixels per inch, so it comes down to 450 pixels and loses almost all of its weight while looking the same on screen and in print at that size. A scanned page that fills the sheet at 300 dpi comes down to 150. Text, fonts and vector graphics are never touched, so what you could select and search before you still can, and links, bookmarks and form fields come through with it.

It only ever helps. The smallest of the original, the rebuilt file and the recompressed file is what comes back, and it is checked page for page against your upload first, so a PDF that has nothing left to give is returned as it was rather than made larger, and the result says so. Some images are deliberately left alone because re-encoding them risks damaging how they look: black-and-white scans, 16-bit and CMYK images, images with an indexed palette, a colour-key or stencil mask, JPEG 2000 images, images too large to decode safely, and any image that also appears somewhere its size cannot be measured, such as inside an annotation. A PDF made up only of those has little to gain.

The work runs on the server, not in the tab, because it needs native tools. The upload travels over an encrypted connection, the job runs on one machine, and both it and the file it produces are deleted once their six-hour retention runs out. Documents over 300 pages are refused with the page count in the message, and a very large one is finished as far as the time allows, biggest images first, and the result says when that happened.

How to use it

  1. Add your PDF. Drop in a single file, or a stack of them. Each file becomes its own job and returns its own result, so a batch of invoices stays a batch.
  2. Let it run. There is nothing to configure. Every file gets the same treatment, and progress moves through optimising and recompressing the images. A scan or a photo-heavy document usually takes a few seconds.
  3. Compare the sizes, then download. The result shows the size it came in at, the size it left at and the percentage saved, with a short line about what was done. If the saving is not worth having, keep your original.

Processing & privacy

Hybrid processing. Smaller jobs can run locally; heavier jobs may use secure server processing.

Common use cases

Getting under an email limit

Mail servers reject on bytes, not on content. A scan or a report full of photos that bounces at 5 MB usually comes back well under the limit, and it is still searchable when it lands.

Sending a phone scan or a photo PDF

Scanner apps and photo-to-PDF tools store every page as a full-resolution picture, so a handful of pages can run to many megabytes. Resampling them to 150 dpi keeps them readable and cuts most of the weight.

Submitting to a portal

Grant, tax and tender portals cap what they accept. Run this first, and if the file is still over a specific figure, use Compress PDF to Target Size, which tightens the images further until it fits.

Cleaning up an export

Files written by word processors and layout apps carry uncompressed content streams, oversized pictures and objects nothing points to any more. Only what the document still uses is written back.

Questions

Where is my file processed?
On the processing service, not in your browser. It is uploaded over an encrypted connection, processed there, and the copies held on the server, the input and the output alike, are deleted about six hours later. The Clear now button clears the tab you are looking at, not the server copy.
Does compressing lose quality?
Yes, in the images, and only there. Resampling to 150 dpi and re-encoding as JPEG discards detail that a screen or a normal print rarely shows, and the text, vector graphics and layout come back untouched. If you need the original resolution, for large-format printing or for pulling images back out later, keep your original.
Why did my PDF barely get smaller?
Because there was little to reclaim. A PDF with no large pictures, one already run through an optimiser, or one whose images are black-and-white or CMYK, has almost nothing this can safely remove. In that case the original is returned unchanged and the result says why, rather than handing you a slightly larger file.
Can I choose how much to compress?
Not here, on purpose. One setting suits nearly every file, and having to choose is what makes tools like this feel harder than they are. If you need a specific size, use Compress PDF to Target Size: you type the figure and it works out how far to go.
I need the file under a specific size
Use Compress PDF to Target Size. It starts with the same recompression and, if the file is still over your figure, applies progressively stronger image settings until it fits, returning the sharpest version that does.
Can I compress a password-protected PDF?
Not one that needs a password to open. The page count is read before anything else, and that read fails without the password, so the job stops with an error rather than returning something broken. Take the password off with Unlock PDF first, then compress the result. A PDF that opens freely but restricts printing or copying is different: it is tidied losslessly with its restrictions kept, but its images are not recompressed.

Related tools

  • Merge PDF — Combine several PDFs into one document in the order you choose.
  • Split PDF — Split one PDF into separate documents by page range.
  • PDF to JPG — Export every page of a PDF as a JPG image.
  • JPG to PDF — Turn one or many JPG photos into a single PDF.
  • Protect PDF — Add a password and set permissions on a PDF.
  • Sign PDF — Draw, type or upload a signature and place it on the page.