Compress PDF Online Free — Reduce PDF Size
A PDF that is too large to email or upload is a common frustration, especially when the file is full of scanned pages or photos. This free compress PDF tool shrinks your file right in your browser, without uploading it anywhere. Here is exactly how it works, because the method matters: each page of your PDF is re-rendered as a picture at a reduced scale and quality, and those pictures are rebuilt into a new PDF. That works very well for scanned documents and image-heavy PDFs, which can shrink by half or more. It works poorly for text and vector PDFs, such as a document typed in Word and saved as PDF, because those files are already small and turning their crisp text into pictures barely saves anything, and can make the text look softer. This page tells you that honestly before you start, so you know what to expect.
One PDF at a time. Best for scanned or image-heavy PDFs.
No PDF selected yet.
Privacy: your PDF never leaves your browser. Compression runs entirely on your device.
How to Use
- Add your PDF. Click the drop zone and choose one PDF file, or drag it in. Its name and original size appear below the box.
- Set the quality. The slider defaults to 70 percent, a good balance for scanned pages. Use 80 to 90 percent if the text must stay crisp, or 50 percent if you need the smallest possible file.
- Click Compress PDF. Each page is re-rendered as a JPEG image at a reduced scale and quality, then rebuilt into a new PDF. The progress bar shows each page as it finishes.
- Check the sizes and download. The result shows the original size, the new size and the percentage saved. Click Download compressed.pdf, then open it and check that the text is still readable before you send it.
Worked Example
Suppose you scanned a 10-page contract on an office scanner and the PDF is 8.4 MB, too large for your email limit of 5 MB. Add the PDF, leave the quality at 70 percent, and click Compress PDF. The expected result is a new file, compressed.pdf, with the same 10 pages, roughly 2.5 to 4 MB in size, a saving of about 50 to 70 percent. Open it and check a page: the text should still be easy to read, though it may look slightly softer than the original scan. If the file is still too large, run it again at 50 percent quality. Now suppose instead the PDF is a 120 KB report typed in Word. Compressing it the same way will barely shrink it, and might even make it larger, because text PDFs are already small and turning their text into pictures adds image data. That is normal, and it is why this tool is honest about its limits.
How the Compression Works, Honestly
There are two very different kinds of PDF. A scanned PDF is really a stack of photographs of pages, and those photographs are usually stored at high resolution, so re-rendering them smaller and at lower JPEG quality removes a lot of wasted data. That is where this tool shines, and savings of 50 percent or more are common. A text or vector PDF is different: its letters are stored as text and its lines as mathematics, which takes almost no space at all. Re-rendering such a PDF turns that efficient text into pictures, which are bigger, not smaller, so the result barely shrinks and the text loses its sharpness and its ability to be selected and copied.
Tips for the Best Result
Start at the default 70 percent quality and only go lower if you need to, because each step down softens the text a little more. If your PDF is a scan, make sure the original scan is straight and clean, since compression will not fix a crooked or faint page.
Frequently Asked Questions
Is compressing a PDF free here?
Yes. Compressing a PDF on this page is completely free, with no account, no sign-up and no watermark on the compressed file.
Are my PDF files uploaded to a server?
No. Your PDF never leaves your browser. Pages are re-rendered and rebuilt entirely on your device, so your document is never uploaded, stored or seen by anyone else.
Why did my PDF barely shrink?
Text and vector PDFs, such as a document typed in Word and saved as PDF, are already very small. Turning their crisp text into pictures barely saves anything and can even make the file larger. This tool works best on scanned and image-heavy PDFs.
Will the text still be readable after compression?
Usually yes at 70 percent quality or above, although text may look slightly softer because pages become pictures. Always open the compressed PDF and check it before sending it, and keep your original file.
Can I still select and copy text in the compressed PDF?
No. Because each page is rebuilt as a JPEG image, the text is no longer selectable or searchable. If you need searchable text, keep the original PDF for that purpose and use the compressed copy only for sharing.