How to Reduce PDF File Size for Email Attachments

The Email Attachment File Size Problem

Many email providers restrict attachment sizes to 20MB or 25MB. If you try to send a scanned contract, portfolio, or ebook that exceeds this, your email will bounce or be blocked. Compressing the PDF is the easiest way to make sure it arrives.

Understanding PDF Structure

PDFs contain font files, vector paths, metadata, and high-resolution images. Images are usually the main reason why a PDF is huge. Scanned documents are essentially a collection of full-page images, which makes them very heavy.

How PDF Compression Works

PDF compressors shrink file sizes using two main techniques:

Image Downsampling: Reducing the resolution (DPI) of embedded images. For example, a 300 DPI image can be downsampled to 150 DPI or 72 DPI, which is standard for screen display.
Image Compression: Applying lossy compression (like JPEG) to embedded photos. This discards visual detail that is invisible to the human eye.
Object Removal: Deleting metadata, thumbnails, unused fonts, and duplicate color profiles.

Step-by-Step Guide to Compressing PDFs

To compress your document securely without buying software:

Use a secure browser tool like our Image Compressor or a dedicated PDF compressor.
Import your PDF. If it consists of images, you can convert them using our Image to PDF tool which optimizes dimensions automatically.
Choose the compression profile: standard compression is best for text with images, while high compression is ideal for drafts.
Download the optimized PDF and inspect it to ensure text remains readable.

Privacy Warnings for Sensitive Documents

Never upload bank statements, legal contracts, or identity documents to unknown cloud services that process files on external servers. Always use tools that process files locally in the browser tab, keeping your private data on your own device.

Conclusion

Reducing PDF size is straightforward. By downsampling images and removing metadata, you can shrink files to email-friendly sizes. Explore similar tools in our PDF Tools Category.