Shrink a PDF so it fits an email attachment limit

The job

Most mail systems stop accepting messages when an attachment is roughly 20–25 MB. A scanned contract or a photo-heavy PDF easily reaches 30 MB. The goal is a smaller PDF that still reads clearly on screen.

Compress it once

Open the PDF compressor, drop the file in, and keep the defaults: 150 DPI and medium quality. For a typical scan that alone is often enough.

• Resolution controls how sharp pages look. 150 DPI is comfortable for reading; 96 DPI is fine for a quick look on a phone; 220 DPI is for documents with small print.
• Quality controls the JPEG artifacts inside each page. Medium is a good balance; low can blur thin text.

Worked example

A 28 MB scan of a 12-page contract, compressed at 150 DPI and medium quality, typically lands around 2–4 MB — well under a 20 MB limit. If the result still exceeds the limit, run it again at 96 DPI and low quality before giving up.

When compression is not enough

Two fallbacks: split the document with Extract PDF pages (send pages 1–6 and 7–12 as two attachments), or check whether you even need a PDF — PDF to image produces JPGs that may be smaller for a one-page scan. Note that a compressed PDF's text is no longer selectable, so keep the original if the recipient needs to copy text or the file must stay searchable.

• Limits: 25 MiB input, 60 pages, encrypted PDFs are not supported.
• If the output ends up larger than the input — it happens with already-optimized PDFs — the tool says so; try a lower resolution instead of sending the bigger file.