How to make a PDF small enough to email

You attach the PDF, press send, and the email bounces back or never leaves: the file is too big. Gmail lets you attach up to 25 MB, and Outlook.com 20 MB; many work email systems set their own, often lower, limits. Scanned documents and PDFs full of photos pass those numbers easily.

Why some PDFs are so large

Text costs almost nothing. What makes a PDF heavy is pictures: phone photos dropped into a report, a scanner set to its highest resolution, or slides exported with full-size images. A single page scanned in color at 600 dpi can be several megabytes on its own. Shrinking a PDF is mostly about storing those pictures more sensibly.

Compress it in a minute

1. Open Compress PDF and drop your file on the page. It stays on your device; nothing is uploaded.
2. Choose a level. Start with Balanced.
3. Download the smaller file. The page tells you the new size, so you can see whether it is under your email limit before you download.

Which level to choose

• Light rewrites the file's structure and strips its metadata. Nothing you can see changes. It helps most with PDFs exported badly from other software.
• Balanced re-saves embedded photos at a sensible size and quality. Text and line drawings stay perfectly sharp and selectable. This is the right choice for almost everything.
• Strong turns every page into a single compressed image. It gives the smallest file, but the text can no longer be selected or searched. Use it for scans, or when nothing else gets you under the limit.

If a PDF is already as small as it can sensibly be, the tool tells you instead of handing back a file that is bigger than the one you started with.

Still too big?

• Send only what's needed: Delete pages you don't need, or extract the ones you do.
• Split the PDF into two or three files and send them in separate emails.
• For scans, try Strong: a scan is already a picture of the page, so you lose nothing you had.

Compression works on your device, so it also works on documents you would rather not upload anywhere: pay stubs, bank statements, medical records.