PDF too big to email: the limits and the fixes

What is the attachment limit for each email service?

These are the figures as we read them in October 2026. Work and school accounts are usually set by an administrator, so your own limit can differ.

The Kindle figures come from an Amazon help page served on a mirror host, because Amazon's main help pages returned an error when we tried. Treat them as limits as read on that page and check Amazon's own page before you rely on them.

Why does my PDF fail when it is under the limit?

Email carries attachments as text. RFC 2045 describes the encoding: it represents 24-bit groups of input bits as 4 encoded characters, and "the encoded data are consistently only about 33 percent larger than the unencoded data." A 20 MB PDF therefore travels as roughly 26.6 MB.

Providers say this in their own words. Microsoft notes that messages routed outside its datacenters get an additional 33% translation encoding increase, and that Outlook on the web restricts what you can send to 25% less than the configured setting. Google's Workspace receiving page says its stated values are the limit after encoding, which adds about a 37% increase. Not every provider says how it counts, so leave a margin: a file of 18 MB is safer than one of 24 MB against a 25 MB limit.

Should you compress at all?

Compression costs quality, so try the options that do not first.

• Send a link. Gmail says that above its limit it automatically removes the attachment and adds it as a Google Drive link. OneDrive links do not count towards the Outlook.com size limit, though a linked file can be up to 2 GB. Apple's Mail Drop sends attachments up to 5 GB that expire after 30 days, though the recipient's email app may have a smaller limit that prevents delivery.
• Split the file. Two 12 MB emails get through where one 24 MB email does not. The split tool cuts by page range.
• Remove pages you do not need. Blank scans, cover sheets and duplicates add up. The delete pages tool removes them.

If the recipient needs one attached file, such as a portal upload or a work address with a strict limit, compress.

Which size should you compress to?

Pick the page by situation. Each one runs in your browser and aims at a fixed size.

• 5 MB: the normal choice for email. It leaves a wide margin under a 20 or 25 MB cap, even after encoding.
• 10 MB: stays under many mail limits while keeping scans readable. Use it when 5 MB looks too soft.
• 2 MB: for older corporate mail servers and anything with a strict inbox rule.
• 1 MB, 500 KB, 200 KB and 100 KB: for forms and portals with hard caps. Expect visible quality loss on image-heavy pages.

If your target is not on the list, the size hub shows them all. For the general method, see our guide to reducing PDF file size.

What does compressing a big PDF cost you?

Be clear about the trade. In the target size mode and on the size pages, every page is re-rendered as a JPEG. Text is no longer selectable or searchable afterwards, and small print gets softer. A scanned PDF has no real text anyway, so it loses little. A contract exported from Word may lose more than it gains.

A mostly text PDF may not shrink much at all. When it cannot reach the target, the tool tells you the smallest size it managed instead of handing you something unreadable.

The compress tool also has a keep text selectable mode. It recompresses only the images inside the PDF, and text, links and vector graphics stay as they are. Files that are mostly text will barely shrink in that mode, and if the file has no images it can recompress, the tool says the size barely changed. Use it first when your PDF is a text document with a few photos.

What about iPhone and Kindle?

On an iPhone using iCloud Mail, the stated limit is 20 MB, and Mail Drop lifts that to 5 GB for attachments that expire after 30 days. The recipient's email app may still reject a large message. In Gmail on the phone, the Drive link behaviour above applies. Outlook for iOS and Android has a stated message limit of 33 MB on Exchange Online.

For a Kindle, the web upload accepts files of 200 MB or smaller. The email route allows 50 MB per attachment and no more than 25 documents per message. Amazon's page also says Send to Kindle does not support password protected or encrypted files, so a locked PDF will fail even at a small size.

How can you check that compression stays on your device?

Open your browser's DevTools with F12 and go to the Network tab. Tick Preserve log, then compress a real file. If the file were uploaded, you would see a request roughly the size of the PDF. The page's Content-Security-Policy also restricts network connections to our own site. For the wider question, read does a PDF tool upload your file.

Straight answers (PDF too big to email: the limits and)

Related to PDF too big to email: the limits and

• Compress PDF: Shrink a PDF to fit email and upload limits, with a level or target size.
• Split PDF: Split a PDF into separate single-page files or extract a page range.
• Delete PDF Pages: Remove unwanted pages from a PDF document.
• How to Reduce PDF File Size Without Losing Quality (2026)
• Compress PDF Without Losing Quality: What You Can Keep
• Can you merge a PDF without losing its digital signature?
• Compress a PDF to a target size