Email and messenger attachment size limits, in 1 table

Email attachment limits, checked on 11 October 2026

Each figure comes from the provider’s own help page, named in the last column. “Send at most” is the stated limit divided by 1.33, the size of file that still fits once encoded.

Two things the table cannot show. The limit counts the whole message, so 3 PDFs of 7 MB each are one 21 MB message. And company mail servers set their own numbers; if you write from a work address, the administrator’s limit beats anything above.

Chat apps and messengers

Messengers are far more generous, because they do not encode files as text.

On WhatsApp, send a PDF with the document option, not as a photo. A document arrives exactly as you sent it. The real limit on a phone is usually mobile data and the recipient’s patience, not the 2 GB.

Why a file under the limit still bounces

Email was built for text. Before an attachment is sent, it is turned into plain characters, and that encoding adds about a third to its size. Microsoft’s Exchange Online documentation puts the figure at 33 percent.

So the working numbers are:

• 25 MB limit: send 18 MB or less.
• 20 MB limit: send 15 MB or less.
• 10 MB limit: send 7 MB or less.

What happens when you go over

It depends on who notices first.

1. Your own mail app refuses. Gmail on the web swaps the file for a Google Drive link above 25 MB. Outlook.com offers a OneDrive link. iCloud Mail offers Mail Drop, which carries up to 5 GB. In each case the recipient gets a link, not an attachment, and the file now sits in your cloud storage.
2. A server on the way refuses. The message leaves, then comes back as a “non-delivery report” a few minutes later. Microsoft’s documentation describes exactly this for messages over a mailbox’s limit.
3. The recipient’s server refuses. Their limit can be lower than yours. A bounce from their side looks the same as one from yours, and nothing in your mail app warns you beforehand.

A link is fine for holiday photos. For a contract or a medical record it changes who can open the file and for how long, which is why compressing or splitting is often the better route. The guide on sending a large PDF weighs the 3 routes.

Over the limit: make the PDF fit

Most oversized PDFs are scans or photos, and those shrink a lot. On our test files, the Email preset takes a 10-page colour scan from 17.6 MB to 1.7 MB, and 5 phone photos from 14.7 MB to 395 KB. Text stays text and stays sharp.

1. Drop the PDF on the tool above. It opens in your browser; nothing is uploaded.
2. Keep the Email preset, or type a size target such as 15 MB if you know the limit.
3. Press Compress and read the result: the size before and after, and what changed.
4. Download the smaller copy and attach that one. Keep the original.

What this page cannot fix

Limits change, and providers do not announce it. This table was checked on 11 October 2026 against each provider’s help page; when it matters, look at the page named in the source column.

Compression cannot shrink what is not pictures. A PDF that is mostly text is already small, and the tool returns it unchanged with a line saying so. If a file still will not fit at a quality you can accept, cut it into parts with Split PDF and send 2 emails, or send only the pages the reader needs with Extract pages. For the quick version of all this with a bounced email in front of you, see PDF too big to email; for upload forms with their own caps, see PDF size limits by portal.