How to compress a PDF to reduce file size
Quick answer
In Adobe Acrobat: File > Save as Other > Reduced Size PDF (or Compress PDF tool). For images-heavy decks, use PDF Optimizer and downsample images to 150–220 ppi for screen use.
Avoid repeated recompression of already-scanned PDFs - quality drops fast. Keep an original archive copy.
Exact menu names vary by Acrobat Pro vs Reader (Reader has fewer optimize tools).
Compress a PDF
Acrobat Pro
- Open the PDF.
- Use Compress PDF / Reduce File Size from Tools or File menus.
- Choose screen vs printing quality, then Save under a new filename.
Print to PDF (moderate savings)
- Open the PDF > Print > destination Microsoft Print to PDF (Windows) or Save as PDF (Mac).
- Lower print quality if the dialog offers it, then save.
- Compare size and readability.
Online tools
- Only for non-confidential files.
- Upload, compress, download, delete from the service if possible.
What makes PDFs huge
- High-resolution embedded images
- Scanned pages as images
- Embedded fonts subsets sometimes help little vs images
If you need small + searchable
Run OCR after scanning at reasonable DPI (300 for text) instead of 600+ color photos of pages.
Frequently asked questions
Text looks blurry after compress?
You downsampled too aggressively - recompress from the original with milder settings.
Email still rejects the file?
Zip the PDF, split pages, or host a link instead of attaching.
Does compressing remove passwords?
No - security settings are separate.
Sources checked: Adobe Acrobat Help. Verified October 2026.