Large PDF files are a headache. Email attachments get rejected, upload portals throw errors, and cloud storage fills up fast. The good news is that most PDFs can be compressed dramatically — often by 60–90% — without any visible loss in quality. Here's everything you need to know.
Why are PDFs so large?
PDFs often become bloated for a few reasons. High-resolution images embedded in the file are the biggest culprit — a single scanned page can add several megabytes. Embedded fonts, metadata, revision history, and colour profiles also add unnecessary weight. Compression works by intelligently reducing these without touching the actual readable content.
The four compression levels explained
Most PDF compressors — including ours — offer multiple levels:
• Screen — Maximum compression. Ideal for sharing via email or uploading to web portals. Images are downsampled to 72 dpi. Best for documents that will only be read on screen.
• eBook — A balanced middle ground. Images are kept at 150 dpi. Good for most everyday documents — reports, invoices, forms.
• Printer — Light compression. Images stay at 300 dpi. Use this if the PDF will be printed and quality matters.
• Prepress — Minimal compression. Best for professional publishing or design files where every pixel counts.
How to compress a PDF for free — step by step
1. Go to tecpdf.com/compress
2. Drag and drop your PDF or click to select it
3. Choose your compression level (eBook is a great default)
4. Click Compress PDF
5. Download your smaller file
No signup required. Your file is processed on a secure server and permanently deleted immediately after you download. The whole process takes under 30 seconds for most files.
How much smaller will my PDF get?
Results vary depending on the original file. A 10 MB PDF full of high-resolution photos on Screen mode might compress to under 1 MB — a 90% reduction. A text-heavy PDF like a Word document converted to PDF might only reduce by 10–20%, because there's little visual data to optimise. If your PDF is already optimised, the compressor will return the original unchanged rather than making it larger.
Tips for the smallest possible file size
• Choose Screen compression for anything going via email or web upload
• Remove unnecessary pages before compressing — use our Split PDF tool to extract only the pages you need
• Avoid scanning documents at 600 dpi when 150–200 dpi is perfectly readable
• If you're converting from Word, avoid embedding high-res images unless necessary
Is compressed PDF quality really preserved?
For text-based content — yes, completely. Text in PDFs is stored as vector data, not pixels, so it's never affected by compression. What changes is the resolution of embedded images. On Screen mode, images are downsampled to 72 dpi — fine for reading on any screen, but you'd notice the difference if you zoomed in to 400%. For print use, choose Printer or Prepress mode instead.
Ready to compress your PDF? Try our free tool at tecpdf.com/compress — no signup, no watermark, instant results.