How to Compress a PDF

“The file is too large to attach.” It usually strikes at the worst moment — a form with a 2 MB limit, an email that bounces, a portal that refuses your upload. The fix is to compress the PDF: shrink its file size while keeping it perfectly readable. This guide explains what makes a PDF heavy, how compression works, and how to do it in seconds.

What makes a PDF so large?

Text is tiny. What inflates a PDF is almost always images — scanned pages, high-resolution photos, or screenshots saved at far more detail than a screen or printer needs. A single phone photo can be several megabytes; put ten in a document and you have a file no inbox will accept. Compression targets exactly this: it re-encodes the images at a sensible resolution and quality, leaving your text crisp.

Compress a PDF, step by step

1. Open the tool. Go to Compress PDF and drop your file in.
2. Pick a quality level (see below). The default suits most documents.
3. Compress and download a smaller PDF, ready to email or upload.

Which quality level should I choose?

• Screen — the smallest file, tuned for on-screen reading. Great for email and web upload where print sharpness does not matter.
• Ebook — the balanced default: noticeably smaller with quality most people cannot tell apart from the original.
• Printer — higher resolution kept for clean printing; a more modest size reduction.
• Prepress — maximum quality for professional printing; use only when you truly need it.

Start with ebook. If the file is still over your limit, step down to screen. If a document is mostly text, another big win is converting it to grayscale — dropping colour data alone can shrink a scanned file substantially.

Realistic expectations

A PDF full of high-resolution photos can often drop by 50–80%. A PDF that is already mostly text will barely shrink — because there was little to remove in the first place. Compression is not magic: it removes redundant image detail, so the more image-heavy your file, the bigger the saving. If a document hardly shrinks, that is a sign it was already lean.

Other ways to make a PDF smaller

• Remove pages you do not need before compressing.
• Convert to grayscale with PDF to Grayscale if colour is not essential.
• Optimise for the web with Optimize PDF for Web so it opens page-by-page while downloading.

Is it private and free?

Compression uses professional PDF software running on our secure server. Your file is uploaded over an encrypted HTTPS connection, processed in an isolated workspace, and deleted automatically the moment the smaller PDF is sent back — nothing is stored, logged or shared. It is free, with no watermark and no sign-up.

Frequently asked questions

Will the text get blurry? No. Text stays sharp and selectable — compression only re-encodes images, not the text layer.

My PDF did not get much smaller. Why? It is probably already text-based with few images. Try a lower quality level, or grayscale if it is a colour scan.

Can I compress a scanned document? Yes — scans are images, so they usually compress very well. If you also need to search the text, run OCR PDF first.

Compress your PDF now

Open Compress PDF to slip under any email or upload limit without losing readability — free, secure and deleted right after. Combining files too? Merge PDF first, then compress the result.