Compress PDF – Reduce a PDF to an Exact File Size
About PDF Compressor
Add a PDF and either give it a target size in kilobytes or pick a compression level. The file is rebuilt smaller in your browser and downloaded — nothing is uploaded.
Upload forms and government portals almost always cap the PDF you attach — “file must be under 100 KB”, “maximum 500 KB”. This tool compresses to that number: it renders each page, re-saves it as a JPEG image inside a new PDF, and lowers the resolution and quality until the whole file fits the limit you set. The result shows the final size, page count and settings used.
Because pages are turned into images, text in the compressed PDF is no longer selectable or searchable. That is the right trade for a scan or a photo-heavy document you just need to get under a size limit; for a text PDF you want to keep searchable, send fewer pages instead. If a PDF is already smaller than anything compression can produce, the original is returned untouched.
Everything runs on your device using your browser — the PDF is never uploaded, there is no account, and there is no watermark on the output. It works on a phone as well as a laptop, though a very large PDF is limited by your device's memory.
Choosing a target size
Check the limit on the form first, and enter a figure a little under it. Sizes here use 1 KB = 1,000 bytes, the convention most upload forms apply, so a PDF compressed to 'under 500 KB' will pass a 500 KB check. If a form says '100 KB' and your scan is several megabytes, the PDF has to be reduced hard — expect noticeably softer pages — while a limit of 1 MB or more usually leaves the pages looking much as they did.
Page count matters as much as the setting. A fixed size spread over twenty pages leaves each page far less room than over two, so if a heavily compressed result is unreadable, remove pages you do not need — with the PDF Toolkit's Split — rather than pushing the target lower.
Target size, or a compression level?
Use the Target file size tab when something enforces a number: an application portal, an email gateway, a form field. It works toward the limit and reports the size it reached. Use the Compression level tab (Light, Balanced, Strong) when no number is set and you simply want a smaller file — it is quicker to judge by eye, and Light keeps more detail than Strong. If neither is satisfactory the file may already be near the smallest it can get without damaging legibility.
When the result looks wrong
Text is blurry: the target was too low for the page size. Raise it, or send fewer pages. Text cannot be selected or searched: that is expected, because each page is rebuilt as an image to reach a guaranteed size; keep your original for any copy that needs to stay searchable. The file came back unchanged: it was already smaller than an image-based rebuild would be, which happens with text-only PDFs, and the original is already within what compression can offer.
It is slow or stops on a phone: every page is rendered in memory, so long or high-resolution scans are limited by the device. Try a laptop, or split the document and compress the parts. It says the PDF is password-protected: remove the password in the app that created it, then try again.
What it is not for
It will not shrink a PDF losslessly or keep its text layer. For a document you will keep editing or archiving, compress a copy and keep the original. For a bundle of photos, the Images to PDF tool followed by this one gives you more control over the final size than compressing an already-large PDF.
What you can use it for
- Shrink a scanned document to the KB limit on a job or exam application portal.
- Compress a photo-heavy report so it fits an email attachment cap.
- Reduce a bank statement or invoice PDF before uploading it to a form.
- Get a multi-page scan under a government portal's maximum file size.
How it works, step by step
- 1
Add your PDF
Drag in or choose one PDF file. It is read locally — nothing is uploaded.
- 2
Set a target
Enter a maximum size in KB on the Target file size tab, or pick Light / Balanced / Strong on the Compression level tab.
- 3
Compress
Each page is rendered and re-saved on your device. A progress bar shows which page it is on.
- 4
Download
Check the final size, then save the compressed PDF.
Frequently asked questions
Is my PDF uploaded to a server?
No. The PDF is read, rendered and rebuilt entirely in your browser. It is never uploaded, stored or logged.
How does compressing to an exact KB size work?
The tool renders each page to an image, then lowers the resolution and JPEG quality — guided by a quick test of the first page — until the whole PDF fits under your target, and reports the size it reached.
Why is the text not selectable after compressing?
To guarantee a small size the tool replaces each page with a flattened image, which removes the searchable text layer. If you need the text kept, reduce the page count instead of compressing.
It says my file is already small enough — what does that mean?
Some PDFs, especially plain text ones, are already smaller than a rebuilt image version would be. In that case the original file is offered unchanged.
What is the largest PDF I can compress?
There is no fixed limit, but because everything runs in memory on your device, very large or high-page-count PDFs may be slow or run out of memory on a phone.
Can it compress a password-protected PDF?
No — encrypted PDFs are rejected with a clear message. Remove the password first, then compress.