How to make a PDF small enough to email

Most email services won’t send attachments over about 20–25 MB. Here’s how to get a PDF under the limit without wrecking it.

5 minute read. Updated October 27, 2026.

You finish a document, attach it, press send, and get told the file is too large. It’s one of the most common PDF problems, and it usually has a simple cause: the PDF contains images that are far bigger than they need to be.

What the limits are

Gmail allows attachments up to 25 MB, and Outlook.com up to about 20 MB. Work email systems are often stricter, sometimes 10 MB. Encoding an attachment for email makes it roughly a third larger than the file on your computer, so a 19 MB file can fail on a 25 MB limit. Aim for well under the limit, not just under it.

Why PDFs get big

Text takes almost no space. A 300-page novel can be under 2 MB. What bloats a PDF is images: scanned pages, phone photos, and screenshots. A single page scanned at high resolution can be several megabytes, so a 20-page scan can easily reach 50 MB or more.

That tells you what to expect before you start. If your PDF is mostly text, compression won’t save much, because there isn’t much to remove. If it’s scans or photos, you can often cut the size by 70% or more.

How to compress it

Open Compress PDF and add your file. It stays on your device; nothing is uploaded.
Pick a level. Recommended suits most files: it shrinks the photos and scans inside the PDF and leaves text sharp. Strong squeezes images harder. Maximum is for scanned documents that are still too big.
Select Compress PDF and check the before and after sizes.

Choosing the right level

Recommended and Strong only touch images, so text stays selectable and searchable, and charts and diagrams drawn as vectors stay crisp. Maximum works differently: it redraws every page as a compressed image. That squeezes scans hardest, but the text in the result can’t be selected or searched. For a signed contract or an ID scan that rarely matters; for a report someone needs to copy text from, stick with Recommended or Strong.

Open the compressed file and zoom in on the smallest text before you send it. If it’s blurry, go back one level.

When it’s still too big

Split it. Use Split PDF to break it into parts and send them in separate emails.
Remove pages nobody needs. Blank pages, duplicate scans and cover sheets add up. Organize PDF lets you delete them.
Use a file link. For very large documents, upload the file to a cloud drive you already use and send a link instead of an attachment.

Preventing it next time

If you scan with your phone, most scanner apps have a quality or size setting. “Medium” or 150–200 dpi is plenty for documents you’ll read on screen or print on an office printer. Scanning at 600 dpi produces huge files with no visible benefit for ordinary paperwork.