Why PDF files get so large
PDFs can balloon in size for several reasons: high-resolution images embedded in the file, uncompressed fonts, embedded color profiles, and metadata bloat. A single scanned page at 300 DPI can easily reach 2–3 MB. A 20-page report with photos? Easily 40 MB.
The two main compression approaches
1. Image resampling
Most of a PDF's size comes from images. Reducing image resolution from 300 DPI (print quality) to 150 DPI (screen quality) cuts image data by roughly 75% with almost no visible difference on screen.
2. Font subsetting
Fonts embedded in PDFs often include every character in the typeface, even if your document only uses 40 of them. Subsetting strips out unused characters.
How to compress a PDF with PDFCraft
- Go to the Compress PDF tool.
- Upload your file (up to 200 MB).
- Choose a compression level:
- Screen — smallest file, optimized for web viewing
- eBook — balanced quality, great for email
- Printer — high quality for printing
- Click Compress and download your smaller file.
Tips for best results
- Scanned documents compress dramatically — sometimes 10× smaller.
- Text-only PDFs are already small and gain little from compression.
- If quality looks degraded, try the Printer preset instead of Screen.
- For archiving, use eBook preset — it balances size and fidelity well.
How much smaller can it get?
| Original size | After compression | Reduction |
|---|---|---|
| 10 MB scanned document | 1.2 MB | −88% |
| 5 MB presentation with photos | 1.8 MB | −64% |
| 2 MB text report | 1.6 MB | −20% |
Compression works best on image-heavy files. Text-only PDFs are harder to shrink because text is already stored efficiently.