How to compress a PDF without losing quality
Published
Email attachments are often capped at 20 or 25 MB, and upload forms at much less. Here is how to make a PDF smaller while keeping text sharp, and what actually makes PDFs big.
Why some PDFs are so large
Text is tiny: a hundred pages of plain text is often under a megabyte. What makes PDFs large is pictures. Scans and photos straight from a phone camera can be 3 to 5 MB each, and a scanned contract is really a stack of photographs.
Good compression therefore shrinks the pictures and leaves the text alone, so headings and small print stay perfectly crisp.
Choosing a compression level
Recommended re-encodes photos at a quality you will not notice on screen or in print, and usually saves 50 to 90 percent on scanned or photo-heavy files. Strong goes further for email or web forms, with slightly softer photos. Lossless only repacks the file structure, so nothing changes visually; it helps most on files exported by older software.
Step by step
- Open the Compress PDF tool and add your file.
- Choose Recommended, or Strong if the file must be very small.
- Press Compress PDF. The result shows how much smaller it got.
- Open the result and check that it still looks right before you send it.
If the file barely shrinks
A PDF that is mostly text is already efficient, so there is little to remove. If a scanned file is still too big, split it into parts with Split PDF, or remove pages you do not need.