🔒 100% browser-based · No uploads

Free Online PDF Compressor

Last updated: October 30, 2026

Compress PDF is a free online PDF compressor. Compress PDF files and reduce PDF file size fast for email, web forms and sharing — 100% client-side, so your file never leaves your device.

Drag & drop your PDF here or click to browse · PDF files only
Choose PDF File

PDF

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Compression level

Fine-tune

Image resolution (DPI) 110 Lower DPI = smaller file. 72 for screens, 150+ for printing.

Image quality 70% JPEG re-encoding quality applied to every page.

Convert to grayscale (extra savings for documents that don't need color)

Preparing…0%

Original Size

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Compressed Size

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Download Compressed PDF

Your PDF is processed locally in your browser and never uploaded.

Why use Compress PDF?

A fast, private PDF size reducer that works on any device — desktop, tablet or phone — without installing software.

Secure & private

Zero server uploads. Every page is compressed on your own device, so confidential documents stay confidential.

Fast compression

No waiting in upload queues. Pages are processed instantly with live page-by-page progress.

Full control

Pick a preset or fine-tune DPI and JPEG quality to hit the exact file size you need.

Clear size metrics

See original vs. compressed size side by side with the exact percentage saved.

Works everywhere

Runs in Chrome, Edge, Firefox and Safari on Windows, macOS, Linux, Android and iOS.

Free, no sign-up

No accounts, no watermarks, no daily limits. Just drop a PDF and download the smaller version.

How to compress a PDF online

Reduce PDF file size in four simple steps:

Upload your PDFDrag and drop a PDF into the upload zone or click “Choose PDF File”.
Choose a compression levelSelect Low Compression (High Quality), Balanced or Extreme Compression — or adjust DPI and quality manually.
Click “Compress PDF”Each page is rendered and re-encoded in your browser while the progress bar shows which page is being processed.
Download the resultCompare original and compressed sizes, then click “Download Compressed PDF”.

PDF compression quality guide

Which setting should you use? Match the preset to where your PDF is going.

Preset	DPI	JPEG quality	Typical savings*	Best for
Low Compression (High Quality)	150	85%	20–60%	Printing, archiving, detailed scans
Balanced	110	70%	50–80%	Email attachments, sharing, reading on screen
Extreme Compression	72	45%	70–95%	Web uploads, job portals, forms with size limits

*Savings are largest on scanned and image-heavy PDFs. Text-only PDFs may not shrink because pages are converted into images.

Frequently asked questions

Everything you need to know about compressing PDFs with Compress PDF.

Is Compress PDF free to use?

Yes. Compress PDF is completely free with no sign-up, no watermarks and no file limits beyond what your device's memory can handle.

Are my PDF files uploaded to a server?

No. Compress PDF runs entirely in your browser. Your PDF is read, rendered and re-encoded on your own device and is never uploaded, stored or shared.

How does Compress PDF reduce PDF file size?

Each page is rendered with pdf.js at your chosen DPI, re-encoded as an optimized JPEG image at your chosen quality, and reassembled into a new PDF with jsPDF at the original page dimensions.

Can I compress a PDF without losing quality?

Use the High Quality preset (150 DPI, 85% JPEG quality) for results that look nearly identical on screen and print well, while still shrinking image-heavy or scanned PDFs significantly.

Which compression level should I choose?

High Quality is best for printing, Balanced is ideal for email and general sharing, and Extreme gives the smallest file for web uploads and forms with strict size limits.

Will the text in my compressed PDF still be selectable?

No. Because pages are rasterized into images, text in the compressed PDF is not selectable or searchable. Keep your original if you need editable or searchable text.

Why is my compressed PDF larger than the original?

Text-only or already optimized PDFs store text as compact vector data. Converting them to images can increase size. Try a lower DPI or the Extreme preset, or keep the original file.

Are all the tools on FreeToolCabin tested for quality and accuracy?

Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.

More free PDF & file tools

Fast, private, browser-based productivity tools from the same family as Compress PDF.

What decides how much your PDF shrinks

Because this compressor turns every page into a JPEG image, the savings depend on what the pages contain, not just on the setting you pick:

Scanned documents and photo pages shrink the most. A scan saved at 300 or 600 DPI holds far more pixels than a screen needs, so dropping to 110 or 72 DPI removes most of the weight.

Page count matters more than you might expect. Each page becomes its own image, so a 40-page report at 150 DPI can end up larger than a 5-page photo brochure at the same setting.

Page size scales the image too. An A3 or tabloid page has roughly twice the area of A4 or Letter, so it produces about twice as many pixels at the same DPI.

Color adds data. Turning on grayscale removes the color information from each page image, which helps most on documents that are mostly black text on white.

Hitting a specific upload limit

Job portals, government forms and school systems often cap uploads at a fixed size such as 1 MB, 2 MB or 5 MB, and many email services refuse attachments above roughly 20 to 25 MB. To reach a target without guessing:

Start with Balanced and check the compressed size shown next to the original.

If it is still too big, lower the DPI first. Halving the DPI cuts the pixel count to about a quarter, which usually has a bigger effect than lowering JPEG quality.

Then lower image quality in small steps and switch on grayscale if color is not needed.

If the file is still over the limit, remove pages you do not need with Split PDF before compressing again.

Before you submit, open the result and zoom to 100% to confirm small print, signatures and stamps are still legible.

When compressing is the wrong fix

Rasterizing pages is a trade-off. Keep the original, or choose another approach, in these cases:

Contracts and forms you still need to fill in: form fields and links become part of the image and stop working.

Documents someone will search or copy from: text is no longer selectable, so a reviewer cannot copy a clause or search for a name.

Text-only exports from Word or Google Docs: these are usually already small, and converting them to images can make them larger.

Files headed to a print shop: printers typically expect 300 DPI, which is higher than the top preset here.

If you only need a few pages as pictures, PDF to JPG may be a better fit than shrinking the whole document.