Compress PDF

Why PDF files get so big

A PDF full of text is tiny: a hundred pages of text can weigh less than a photo. What makes a PDF heavy is almost always the images inside it, such as scanned pages, photos pasted into a report or high-resolution graphics. A phone scan of a single page can easily reach several megabytes. Compressing a PDF therefore means making those images lighter.

How this tool compresses

It finds the photos and scans stored inside the PDF, reduces their dimensions where they are larger than any screen or printer needs, and saves them again at a lower quality. The text, lines and vector graphics are left exactly as they were, so the words stay crisp, selectable and searchable. You choose how far to go:

• Light keeps images almost as sharp as the original.
• Recommended gives a big reduction with no visible difference at normal zoom.
• Strong pushes further for the smallest file that still reads well on screen.
• Maximum turns each page into a picture. It is the only option that works on some scanned documents, but the text is no longer selectable, so it is worth using only when you need it.

When compression will not help

A PDF that is mostly text is already small, and there are no photos to shrink. In that case the tool tells you and keeps the original instead of giving you a file that is barely different. The same applies to images that are already stored efficiently.

Scans and signatures

If you scan documents yourself, scanning at 150 to 200 dpi in black and white or grayscale produces far smaller files than color at 600 dpi and is still perfectly readable. And if a PDF is digitally signed, compressing it changes the file, so the signature in the new copy will no longer be valid. Keep the signed original for any purpose that needs it.

Need an exact size?

Many portals and email services set a limit, often somewhere between 2 and 25 MB. If you need a PDF to fit a specific limit, use reduce a PDF to an exact size, which keeps trying until the file fits.