Compressing a PDF to fit Gmail and Outlook attachment limits

"Your message has an attachment that's too large" is a familiar bounce for anyone who's tried to email a scanned contract or a photo-heavy report. Gmail caps attachments at 25MB; Outlook.com and Microsoft 365 typically cap at 20MB (and some corporate configurations set it lower still) — limits that a handful of scanned pages at camera resolution can hit surprisingly fast.

Compress vs. Compress to Target Size

Compress PDF shrinks a file by re-encoding its pages at a compression level you choose — fast, and usually enough when you're not chasing an exact number. Compress to Target Size solves the more specific version of this problem: tell it the size you need to land under, and it works through compression levels for you until the result fits — useful when you know the exact ceiling (say, 20MB for an Outlook recipient) and don't want to guess at a percentage.

If compression alone isn't enough

A handful of very large scanned images sometimes can't shrink enough through compression alone without becoming illegible. In that case, splitting the document into two smaller emails (Split PDF) or sharing a link instead of an attachment are the practical fallbacks — no compression setting fixes a file that's fundamentally too much content for one message.