Compress PDF

Why PDFs get large (usually images)

Text takes almost no space; what bloats a PDF is images, especially scanned pages and high-resolution photos stored at far more detail than a screen or printer needs. That is why a five-page scan can be bigger than a hundred-page text document.

Compression mainly re-encodes those images at a sensible resolution and quality, and tidies redundant data, cutting file size while keeping the document perfectly readable.

Getting under an email limit

Attachment limits are a common reason to compress: Gmail caps attachments at 25 MB and Outlook is often around 20 MB, and a photo-heavy PDF passes that quickly. Aiming comfortably under the limit, around 10 MB, is a safe target.

For scanned documents, scanning in grayscale when colour is not needed produces a much smaller file to begin with. This compressor runs locally, so your document is never uploaded.

How much smaller will my PDF get?

It depends on the file. PDFs with redundant structure or uncompressed streams shrink the most; already-optimized or image-heavy PDFs may only reduce a little.

Does compression lower quality?

This tool optimizes the document structure and object streams without re-rasterizing pages, so text stays sharp and the visual content is preserved.

Is my document uploaded anywhere?

No. Compression is performed locally in your browser with pdf-lib, so your file never leaves your device.

Why compress a PDF?

Smaller PDFs are faster to email (many services cap attachments around 25MB), quicker to upload, and take less storage space.