Our take: Adobe Acrobat Online made the smallest file (−96.5%). iLovePDF gave the best balance, and PDF24 is the pick if you want no usage limits.
- ✓ Same file, same day, measured by us
- Test file 2,876,218 bytes (3 pages)
- ! All 7 upload your file
We ran one PDF through 7 free online compressors on their default (recommended) setting and measured the output size. Every tool uploaded the file to its servers.
Results (smallest first)
| Rank | Tool | Setting | After | Reduction | Free terms | File retention |
|---|---|---|---|---|---|---|
| 1 | Adobe Acrobat Online | High (default) | 99 KB | −96.5% | No sign-up needed | Deleted unless you sign in or save |
| 2 | PDFgear | Default | 223 KB | −92.3% | No sign-up or email | Says files are deleted permanently |
| 3 | iLovePDF | Recommended | 311 KB | −89.2% | No sign-up needed | Deleted after 2 hours (official) |
| 4 | PDF Candy | Recommended | 354 KB | 약 −88% | Hourly usage limit | Deleted after 2 hours (official) |
| 5 | Sejda | Medium (default) | 382 KB | −86.7% | Limited free tasks | Retention not stated |
| 6 | PDF24 | DPI 144 · quality 75% | 510 KB | −82.3% | No usage limits | Deleted after 1 hour (official) |
| 7 | LightPDF | Default | 850 KB | −70.4% | 3 free tasks | Not confirmed |
Which one to use
- Smallest possible file: Adobe Acrobat Online. Photos lose a lot of quality, so pick Medium for print.
- Balance of quality and size: iLovePDF (−89%). Officially deletes files after 2 hours.
- Many files, no limits: PDF24. No usage caps; files deleted after 1 hour.
- A hard size limit like “under 2 MB”: LightPDF’s target-size mode. Free use is capped at 3 tasks.
How we tested
- Test file: a 3-page PDF with one 3000×2000 photo, 2,876,218 bytes (2.74 MB). It is a synthetic image with no personal data, generated identically each time.
- Setting: each tool’s default or “recommended” level. Numbers come from the tool’s result screen or its server job response.
- Date: 28 Sep 2026, Chrome desktop, not signed in.
- We compared size only, not visual quality. Photo-heavy PDFs may lose quality as they shrink.
Left out of this comparison
Smallpdf did not complete our automated run that day (free use is capped daily). Soda PDF was left out because downloading the result required creating an account.
Measured 28 Sep 2026 · Tool policies change. Got a different result? Tell us.