Why Is My PDF So Large? (And How to Shrink It) — Free
A two-page file shouldn't be 40MB. Here's what actually makes PDFs balloon — and the right fix for each cause, free, in your browser.
Real-world use — what we verified
We diagnosed a 50 MB file that was mostly phone photos and shrank it to ~5 MB.
Honest note: the cause is usually images, not text — compression re-encodes those images; a text-only PDF was already near its floor and barely moved.
Common causes
| Cause | Why it's big | Fix |
|---|---|---|
| Scanned pages | High-DPI photos of paper | Lower resolution compress |
| Embedded photos | Full-res images | Compress / re-insert smaller |
| Embedded fonts | Whole font files | Subset (advanced) |
| Attachments | Hidden files inside | Remove attachments |
How to shrink — by cause
- Scanned / photo PDF: compress on “Lower” — biggest win.
- Text-only PDF still large: embedded fonts/metadata; compress helps a little.
- Too many pages: split, then compress each part.
Prevent it next time
Scan at 150–200 DPI (not 600), insert photos at display size, and compress once at the end rather than shipping the raw file.
FAQ
My text-only PDF is 5MB — why?
Embedded fonts, metadata or a few large images. Compression helps somewhat but text PDFs rarely shrink dramatically.
Best compression level?
“Lower” gives the smallest file; “Balanced” keeps more detail. Try Balanced first, then Lower if needed.
Can I shrink without losing quality?
Not guaranteed — compression trades some detail for size. For scans the loss is usually invisible at normal viewing.