How to Compress PDF Files Without Losing Quality

Why are PDFs so large?

PDFs can contain high-resolution images, embedded fonts, metadata, and multiple layers. A scanned document can easily reach 10–50MB because each page is stored as a full high-DPI image rather than as text.

• Scanned documents: Each page is a large raster image (often 300 DPI), leading to massive files.
• Embedded images: Photos and graphics inside a PDF are often stored at original quality.
• Fonts and metadata: Embedded fonts and document metadata add to file size.

Compression strategies

1. Reduce image quality. Most of a PDF's size comes from images. Reducing embedded image quality from 300 DPI to 150 DPI can halve file size with minimal visible difference on screens.
2. Remove metadata. PDF files often contain author information, creation dates, revision history, and other metadata that isn't needed for the final document.
3. Flatten form fields. Interactive form fields and annotations add overhead. Flattening them reduces size.
4. Optimize fonts. Subset fonts to include only the characters used in the document, rather than the entire font file.

Common size targets

• Email attachments: Most email providers cap at 25MB. Aim for under 10MB to be safe with multiple recipients.
• Government portals: Indian exam portals often set limits of 500KB–2MB for uploaded documents.
• University submissions: Many online submission systems cap at 5–10MB per file.
• Web downloads: Smaller is always better — under 2MB loads quickly even on mobile data.

Using our PDF Compressor

1. Upload your PDF. Drag and drop or click to browse. We process locally — your document never leaves your device.
2. Choose compression level. Light compression preserves maximum quality; heavy compression achieves the smallest file size.
3. Preview the result. Check that text is still readable and important images are clear.
4. Download. Get your compressed PDF ready for submission.

When compression isn't enough

If your PDF is still too large after compression, consider these alternatives:

• Split into multiple files: Submit multi-page documents as separate smaller PDFs.
• Use image-to-PDF conversion: Convert optimized images to PDF rather than scanning at maximum DPI.
• Extract and re-scan: If the original scan was at 600 DPI, re-scan at 200–300 DPI for documents that don't need print-quality resolution.