How to compress a PDF without losing quality
Shrink oversized PDFs for email and sharing while keeping text sharp and readable — the settings that matter.
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Why PDFs get so large
Most bloated PDFs are full of uncompressed images — scanned pages, photos and screenshots saved at full resolution. The text itself is tiny. Good compression targets the images: downsampling them to screen or print resolution and recompressing them efficiently, while leaving text vectors untouched.
Step-by-step
- Check what is inside the PDF first: a 50-page text report rarely needs compression, while a 10-page scan almost always does.
- Open the Compress PDF tool and upload your file.
- Start with the balanced setting. It typically cuts 60–80% of the size with no visible difference on screen.
- Open the result and zoom to 150% on a photo page. If it still looks clean, you are done.
- Only switch to maximum compression if you must hit a strict attachment limit — text stays readable, but photos get softer.
- Keep the original file. Compression is one-way; you cannot get the discarded detail back.
Common mistakes
Do not compress an already-compressed PDF repeatedly — each pass throws away more detail. And never compress the only copy of an archival scan; work on a copy and keep the original at full quality.
Best settings
- Email attachment: Balanced compression fits Gmail and Outlook limits.
- Screen reading: Images at 150 DPI look sharp on any display.
- Print and archive: Keep the original; compress only the shared copy.
Frequently asked questions
Why are some PDFs so large?
Most bloated PDFs are full of uncompressed images — scanned pages, photos and screenshots saved at full resolution. The text itself is tiny.
How much can balanced compression save?
It typically cuts 60–80% of the size with no visible difference on screen. Open the result and zoom to 150% on a photo page — if it still looks clean, you are done.
Should I compress an already-compressed PDF again?
No — do not compress an already-compressed PDF repeatedly; each pass throws away more detail. And never compress the only copy of an archival scan; work on a copy and keep the original at full quality.
What setting should I use for an email attachment?
Balanced compression fits Gmail and Outlook limits. Only switch to maximum compression if you must hit a strict attachment limit — text stays readable, but photos get softer.
Can I get the discarded detail back after compression?
No — compression is one-way; you cannot get the discarded detail back. Keep the original file.