PDF Compressor
Compress PDF files to reduce size while keeping quality — free, browser-based, no upload
Compression Level
Drag & drop PDF files here, or click to select
Supports multiple files — PDF only
Free Online PDF Compressor — Reduce PDF File Size Instantly
PDF files are the standard for sharing documents — contracts, reports, presentations, manuals, invoices, and more. But high-quality PDFs can become very large. Scanned documents, image-heavy presentations, and print-ready files routinely reach tens of megabytes. That creates problems: email attachments are limited (usually 25 MB), cloud storage fills up fast, slow uploads make sharing frustrating, and large files take longer than necessary to open on mobile devices.
This free PDF Compressor reduces your PDF file size right in your browser. Choose from three compression levels — Low (minimal compression, best visual quality, ~10% reduction), Medium (balanced compression and quality, ~30% reduction), or High (maximum compression, ~50% reduction) — upload one or many PDF files at once, and click Compress All. Each file shows its original size, compressed size, and the exact percentage saved. A summary bar totals everything so you can see the combined savings across all files.
All processing happens in your browser. Your PDFs are never uploaded to a server, never stored remotely, and never read by anyone other than you. When you are done, download each compressed file individually. No signup, no watermarks, no limits on file count or file size.
How PDF Compression Works
A PDF file can contain vector graphics, raster images, fonts, metadata, form fields, annotations, layers, and embedded files. Each of these elements contributes to the total file size. PDF compression reduces size by applying techniques to each element type:
Image downsampling
Images inside the PDF are resampled to lower resolution (for example, from 300 DPI to 150 DPI). This is the biggest size saver for scanned documents and image-heavy PDFs.
Image recompression
Images are re-encoded using more efficient compression. JPEG quality can be reduced, or lossless PNG images can be converted to lossy JPEG where visual quality loss is acceptable.
Font subsetting
If a PDF embeds an entire font containing 10,000+ glyphs but only uses 50, subsetting keeps only the glyphs actually used — dramatically reducing the font data size.
Metadata and overhead removal
Redundant metadata, document revision history, unused objects, and structural overhead are stripped out. This alone can save several percent on complex documents.
The Low compression level applies gentle optimisation with minimal visible quality loss. The High compression level aggressively downsamples and recompresses for the smallest possible file. The Medium level is a compromise: most people will not notice any quality difference, while the file size drops significantly.
When to Compress PDFs
Email attachments
Most email providers limit attachments to 25 MB. Compressing a 40 MB PDF to 20 MB lets you send it directly instead of using a file-sharing link.
Web uploads
Many web portals, government forms, and application systems impose strict upload limits (5 MB, 10 MB, etc.). Compressing ensures your file meets the limit.
Cloud storage savings
If you store thousands of PDFs in Google Drive, OneDrive, or Dropbox, compressing them by 30–50% can free up significant storage space.
Faster page loads on websites
If you host downloadable PDFs on your website (brochures, whitepapers, reports), smaller files mean faster downloads and better user experience.
Mobile viewing
Large PDFs can be slow to render on mobile devices. Compressed PDFs open faster, scroll smoother, and use less memory.
Archiving and backup
Long-term storage of compressed PDFs reduces backup sizes and transfer times without losing content readability.