How to Reduce PDF File Size for Email and Online Forms

"File too large" is one of the most common messages people see when they try to email a document or upload it to an online form. Most email services limit attachments to around 20-25 MB, and many forms allow only 2-10 MB. This guide explains why PDFs become so large and how to make them smaller for free.

Why are some PDFs so big?

A PDF that contains only text is usually small - often under 1 MB even with many pages. Size grows quickly when the PDF contains scanned pages or photos. A scanner or phone camera saves each page as a large, detailed image, and a 10-page scan can easily reach 20 MB or more.

How to compress a PDF step by step

1. Open the Compress PDF tool.
2. Choose the PDF file you want to make smaller.
3. Pick a level: Light keeps the best quality, Recommended is a good balance, and Strong gives the smallest file.
4. Press Compress PDF. When the progress bar finishes, the smaller file downloads and the tool shows how much space you saved.

The tool works in your browser, so your document is never uploaded to our server.

Which compression level should I choose?

• Light (150 DPI): for documents that will be printed or contain small text.
• Recommended (110 DPI): for most emails and online forms. Text stays easy to read on screen.
• Strong (80 DPI): when a form has a very low size limit. Check that small text is still readable.

Good to know

Compression works by turning each page into an optimised image. This gives big savings for scans, but the text in the result can no longer be selected or searched, and links stop working. If your PDF contains mostly text, it is probably already small; in that case the tool tells you and keeps your original.

Other ways to make a PDF smaller

• Remove pages you do not need with Delete PDF Pages.
• Send only part of the document by extracting pages with Split PDF.
• Compress photos before turning them into a PDF with the Image Compressor, then use JPG to PDF.

Summary

Large PDFs are almost always caused by scanned pages or photos. Use Compress PDF with the Recommended level for most cases, and remove unnecessary pages to save even more space.