How to reduce PDF size for email without making it unusable
A practical way to shrink a PDF for Gmail, Outlook, and client email limits while keeping the file readable enough to send.
Start with the reason the email is failing
Most people do not care about compression for its own sake. They care because the attachment is too large for Gmail, Outlook, or a client mailbox. That matters because the right target is not “smallest possible file”. The target is “small enough to send without ruining the document”.
A PDF often becomes heavy because it contains scans, screenshots, oversized images, or pages that were exported from another tool without any size discipline. Text-heavy PDFs usually compress differently from scan-heavy PDFs, so expecting the same result every time leads people in the wrong direction.
Use medium compression first
For email attachments, medium compression is usually the safest place to start. It often reduces enough size to pass common sending limits while keeping text, tables, and page layout comfortable to read.
If the PDF is mostly text with a few images, medium compression is often enough. If the file is a stack of phone scans or scanned paperwork, you may need a stronger setting, but you should still check the output before sending it to someone important.
Check the output like a sender, not like a designer
Open the compressed PDF and inspect the pages that matter: signatures, totals, small tables, ID numbers, and any screenshots. The question is simple: can the other person read what they need without friction?
If the answer is yes, stop there. A smaller file that still works for the recipient is better than chasing another few megabytes while degrading the document further.