How to Compress a PDF (Free & Online)

Alex Chen Updated 2026-06-26 pdf-toolkit

Upload your PDF to PDF24 — open-source, fully free with no daily limits. For faster results, Sejda compresses most files in under 10 seconds.

Step-by-step

Choose a PDF compression tool

For unlimited free compression with no signup, use PDF24 — open-source, browser-based, and processes files up to 100MB. For faster processing with 3 free tasks daily, Sejda delivers compressed files in under 10 seconds. For simple one-click compression, iLovePDF offers 2 free tasks per day with three quality presets.

Upload your PDF file

Drag and drop your PDF into the upload area or click to browse. PDF24 processes files locally in your browser — no data leaves your device, which matters for contracts and tax documents. iLovePDF uploads to cloud servers, so avoid it for sensitive files.

Select compression level

Most tools offer three compression levels. Sejda provides 'Extreme', 'Recommended', and 'Less' — 'Extreme' reduces file size by 60-80% with minor quality loss, while 'Less' keeps near-original quality at 10-30% reduction. iLovePDF labels its presets as 'Extreme', 'Recommended', and 'Less Compression'. Pick 'Recommended' for email attachments — it balances size and readability.

Click Compress and wait

Processing takes 5-15 seconds for a typical 10MB document. PDF24 runs locally so speed depends on your computer — larger files may take 30-60 seconds. Sejda uses cloud processing and finishes most files in under 10 seconds regardless of size.

Download the compressed PDF

Click the download button to save your compressed file. Compare the original and new file sizes — iLovePDF shows both sizes side by side after compression. If the result is still too large, re-upload and select a stronger compression level. The original file stays untouched.

Verify the output quality

Open the compressed PDF in PDF24 or your preferred viewer and scroll through every page. Check that text remains sharp, images aren't pixelated, and fonts render correctly. For documents with charts or diagrams, zoom to 200% to catch quality loss. If quality is unacceptable, re-upload and use a lower compression level.