Why PDFs get so big
A PDF grows large mostly because of images. A page of plain text is tiny, but a scanned page is really a photo, and photos take a lot of space. A brochure full of pictures, or a 30-page scanned document, can easily reach many megabytes. That is when email says "file too large" or an upload form refuses it.
Compressing a PDF means making that file smaller so it is easier to send, upload, and store.
How compression works
The Compress PDF tool re-saves each page as an optimised image at a quality and resolution you choose. Lower quality and lower resolution make a smaller file. You are trading a little sharpness for a much smaller size. For most scans and screen viewing, the difference is hard to notice.
This is why compression works best on scanned or image-heavy PDFs. A PDF that is mostly plain text is already small, so it may barely shrink.
Step by step
- Open the Compress PDF tool.
- Select the PDF you want to make smaller.
- Pick a quality level and a resolution. Lower settings mean a smaller file.
- Click "Compress PDF".
- Download the smaller file and check that it still looks good enough for your use.
Choosing the right quality
Think about where the file will be seen:
- For email or screen viewing: a lower resolution is fine and gives the smallest file.
- For printing: keep a higher resolution so the print stays sharp.
- Not sure? Start in the middle, download it, and open it. If it looks good, you are done. If it is fuzzy, try a higher setting.
One thing to know about text
Because this tool rebuilds each page as an image, the text in the compressed file is no longer selectable or searchable. That is perfect for scans, which are already images. It is less ideal for a text document where you need to copy words later. If you need the text to stay selectable, keep an uncompressed copy too.
Is it private?
Yes. Compress PDF runs entirely in your browser. Your file is never uploaded to a server, so your private documents stay on your device. Many other "compress PDF" websites upload your file to do the work — SimpleFileKit does not, which is safer for anything sensitive.
Extra tips
- Keep the original. Compression removes some detail and cannot be undone, so save a copy of the full-quality file first.
- Split then compress for huge files. If a file is enormous, you can split it and compress the parts.
- Check the target limit. Email often allows about 20 to 25 MB. Aim comfortably under whatever limit you are facing.
A simple example
You scanned a 15-page document and it came out at 30 MB — too big for email. Open Compress PDF, choose a medium quality and a screen-friendly resolution, and you might bring it down to a few megabytes. Open the result to check the pages are still clear, then send it.
Try it now — free and private
Got a file that is too big? Open the Compress PDF tool, pick a quality level, and download a smaller version.