Big PDFs are the silent killer of email attachments and form uploads. Most "compress PDF" tools solve the file-size problem by making your text blurry — here's how to avoid that.
1. Know what's making your file big
Before compressing, it helps to know why a PDF is large. Scanned pages (images of text) are almost always the biggest culprit, followed by high-resolution images embedded for print.
2. Choose a compression level that matches the use case
- Email attachment / form upload: medium compression is usually enough.
- Long-term archive where size matters: higher compression is fine.
- Anything you might print: stick to light or medium compression.
3. Compress the file
- Open a PDF compressor in your browser — no install needed.
- Upload your PDF.
- Pick a compression level (start with "Recommended").
- Download and check the file size.
4. Check the result before you send
Open the compressed PDF and zoom in on a page with text and a page with an image. If text looks soft or images are blocky, choose a lighter compression level.
Common mistakes to avoid
- Compressing an already-compressed file repeatedly — quality loss compounds.
- Using maximum compression by default.
- Forgetting to keep the original uncompressed copy.