Email Attachment Size Limits: Gmail, Outlook, Yahoo, Proton (2026)

"Attachment Too Large": Why It Happens

Email was designed in the 1970s to send text, not videos. Attachments are converted into text (Base64 encoding) to travel through mail servers, and every provider sets a maximum size per message to avoid saturating its servers and those of its recipients.

The result: you attach a 22 MB file, the limit is 25 MB… and the email is still refused. Here's why, and how to work around it.

Attachment Limits by Provider

Provider	Sending limit	What happens above
Gmail	25 MB	Gmail automatically inserts a Google Drive link instead
Outlook.com / Hotmail	20 MB (all attachments combined)	Share via a OneDrive link
Yahoo Mail	25 MB (all attachments combined)	Refused
Proton Mail	25 MB (encoded size)	Refused

These figures come from our file size limits reference, which lists 30+ platforms (email, messaging apps, social networks, work tools) with their sources and the date they were last checked.

Why Is My 20 MB File Refused?

Three traps explain most failures:

1. Base64 encoding: to travel by email, a file grows by about 33%. A 20 MB PDF becomes about 27 MB once encoded — above Gmail's 25 MB. Some providers count the encoded size, others the original size.
2. The recipient's limit: your provider may accept 25 MB, but if the recipient's server only accepts 10 MB (common in companies), the email bounces.
3. MB vs MiB: 25 MB can mean 25,000,000 bytes or 26,214,400 bytes depending on the platform. When you're close to the limit, keep a margin.

Rule of thumb: to be safe, keep the total of your attachments under 15–18 MB.

Check Where Your File Fits

The file limits checker tells you instantly where a file can be sent: drop a PDF, a video or a photo, and see whether it fits on Gmail, Outlook, WhatsApp, Discord, Slack and 25+ other destinations. The file is only analyzed on your device — nothing is uploaded.

If it doesn't fit, one click opens the right tool with the right setting: the PDF compressor, the video compressor on the right preset, the image compressor with a target size…

How to Send a File That's Too Large

1. Compress It

The simplest solution, and often enough:

• PDF: the PDF compressor typically reduces scanned or image-rich documents by 40–80%.
• Photos: the image compressor with a target size; 10 photos at 300 KB = 3 MB instead of 40.
• Video: the video compressor — a 1-minute 4K video can go from 400 MB to 20 MB.
• Audio: the audio compressor — a WAV converted to MP3 loses 80–90% of its weight.

2. Split It

A long PDF can be split into several parts sent in separate emails.

3. Use a Link

For really large files, a link is better than an attachment: Google Drive, OneDrive, Dropbox or WeTransfer (3 GB on the free plan). The recipient downloads the file without clogging their inbox.

Conclusion

Attachments are limited to 20–25 MB on the main providers, but the real limit is often lower because of encoding and the recipient's server. Aim for under 15–18 MB, compress before sending, and use a link for anything bigger.