Your PDF is 45MB and email won't send it. You need to compress — reduce file size without making the document unreadable. PDF compressors are common, but they work very differently depending on what's making the file large.
What We Compared
- Processing — server upload vs browser-local
- Compression method — image recompression, object removal, font subsetting
- Quality control — adjustable compression level
- Free limits
- Privacy
The Comparison
| Tool | Processing | Method | Quality control | Free limits | Privacy |
|------|------------|--------|-----------------|-------------|---------|
| BrowserStay | Browser (local) | Image recompression workflow | Yes (via image tools) | None | Never uploaded |
| iLovePDF | Server upload | Image + object optimization | Presets | Daily limit | Uploaded |
| Smallpdf | Server upload | Image optimization | Presets | 2/day | Uploaded |
| Adobe Acrobat Online | Server upload | Full optimization | Yes | Limited | Uploaded |
| PDF24 | Server upload | Image optimization | Presets | Generous | Uploaded |
| Sejda | Server upload | Image optimization | Limited | 3/hour | Uploaded |
| Ghostscript | Desktop | Full optimization | Configurable | Unlimited | Offline |
*Based on publicly available information as of 2026.*
Understanding PDF Size
Before choosing a tool, know what's making your PDF large:
| Content type | Typical size | Best compression approach |
|-------------|-------------|--------------------------|
| Scanned pages (images) | 1–5 MB/page | Recompress embedded images |
| Text-only document | 50–500 KB total | Already small; little to gain |
| Mixed text + images | Varies | Target the images |
| High-res photos embedded | 2–10 MB each | Downscale + recompress |
Text-heavy PDFs don't compress much — the text is already tiny. If your 2-page text document is 40MB, it probably contains embedded high-res images or scans.
Server-Upload Compressors
iLovePDF, Smallpdf, Adobe, PDF24, Sejda offer dedicated "compress PDF" tools.
Strengths:
- One-click compression with quality presets
- Handle large files on server hardware
- Adobe offers fine-grained optimization settings
- PDF24 is generous on free tier
Weaknesses:
- PDF uploaded to server — sensitive content exposed
- Smallpdf: 2 tasks/day
- Limited control on free tiers — often just "high/medium/low" presets
- Text-only PDFs show minimal reduction (may disappoint)
Best for: Large scanned PDFs that aren't confidential.
Browser-Based: BrowserStay
BrowserStay doesn't have a dedicated "compress PDF" button. Instead, it uses a local workflow:
- PDF to Image — extract pages as PNG
- Image Compressor — reduce image quality/size
- Image to PDF — rebuild the PDF
Strengths:
- Entire workflow stays on your device
- Full control over image quality and dimensions
- Works well for scan-heavy PDFs
- No daily limits
Weaknesses:
- Multi-step process (not one-click)
- Text-only PDFs won't benefit (no images to compress)
- Rebuilt PDF may lose searchable text (becomes image-based)
- No font subsetting or object stream optimization
Best for: Scanned documents, image-heavy PDFs, confidential files.
Desktop: Ghostscript
Command-line tool for advanced PDF optimization.
Strengths: Most powerful compression, configurable, free, offline
Weaknesses: Command-line only, steep learning curve
Best for: Developers and power users who compress PDFs regularly.
Compression Results to Expect
| Original content | Typical reduction |
|-----------------|-------------------|
| 300 DPI scans | 50–80% smaller |
| Embedded photos | 40–70% smaller |
| Text-only PDF | 0–10% smaller |
| Already optimized PDF | Minimal |
If compression barely helps, your PDF is probably text-heavy or already optimized.
How to Choose
| Situation | Best choice |
|-----------|-------------|
| Scanned confidential document | BrowserStay (image workflow) |
| One-click compress, public file | PDF24 or iLovePDF |
| Text-only PDF | Already small; compression won't help much |
| Maximum control, offline | Ghostscript |
| Hit Smallpdf daily limit | BrowserStay or PDF24 |
Try It Yourself
Compress image-heavy PDFs locally: PDF to Image → Image Compressor → Image to PDF. Your document never leaves your device. See all PDF tools.
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