Gmail's attachment limit
According to Google's official Gmail help page, checked in September 2026, personal Gmail accounts can attach up to 25 MB. Above that, Gmail replaces the attachment with a Google Drive link. That's fine for some people, but many offices, schools and forms expect the file itself in the email.
The limit covers the total of all attachments in one email, not each file. If you're sending three PDFs, add up their sizes and compress each one to a lower target.
The recipient may accept less
Gmail's limit is only the sending side. The recipient's email provider may accept less than 25 MB; Microsoft's documentation, for example, says Exchange mailboxes default to 10 MB. If someone gave you a smaller limit, type that number into the compressor instead.
What gets smaller and what doesn't
PDFs of phone photos and scans shrink the most, because ConvertirDocs recompresses exactly those images. Text and vector graphics stay untouched, so typed text remains sharp and selectable. A PDF that's mostly text is usually already small, and if the result isn't smaller, you get your original back with the message “Your PDF is already optimized”.
It's 100% free, with no sign-up. Compression happens in your browser, so the file never leaves your device before you send it.
Common mistakes and bounced emails
Forgetting the total is the classic one: three 9 MB files are 27 MB together. Another is compressing until small print blurs. If fine print suffers, remove pages nobody asked for with “Remove pages” or split the document into two emails with “Split PDF”.
If the email still won't send or bounces, check the total size of all attachments and ask the recipient what their limit is.