Why Is My Email Attachment Too Large?
Why an attachment gets refused or turned into a link, and how to make it fit.
1. The file is over the limit
Every email service caps attachments. Gmail allows 25 MB per message for personal accounts, according to Google's help centre; work and school accounts use whatever the administrator sets. Outlook.com allows 20 MB. Company mail varies: older self-hosted Exchange servers default to 10 MB, while Microsoft 365 business mail allows more. Ask IT if you are not sure.
The limit is for the whole message, so three 10 MB photos fail just like one 30 MB video.
2. The file is under the limit, but still too big
This is the one that confuses people. Email sends attachments as text, using an encoding called base64, and that makes every file about a third larger on the way. A 19 MB file becomes roughly 25 MB in transit. That is why a file that looks comfortably under 25 MB can still be refused or converted.
A safe target for Gmail is about 18 MB of real attachments. For Outlook.com aim for about 14 MB, and for a 10 MB company limit about 7 MB.
3. Gmail turned it into a Google Drive link
When you attach more than Gmail allows, it does not refuse. It removes the attachment and puts a Google Drive link in the email instead. That works if the other person can open Drive links, but many people cannot or will not, and the link depends on the file's sharing settings. To send a real attachment, make the file smaller.
4. How to make it fit
Video is usually the cause. The MP4 under 25 MB page has an 18 MB setting for Gmail, and the MOV to MP4 page converts iPhone video while it shrinks it.
PowerPoint decks get big because of the photos inside. The PowerPoint compressor recompresses the pictures and leaves the slides alone.
PDFs, especially scans, can be shrunk with the PDF compressor.
Photos can be brought down to a sensible size with the image compressor. Phone photos at full size are 3 to 8 MB each, so a few of them add up fast.
5. The other side has a smaller limit
Your message can leave fine and then bounce because the recipient's server accepts less. If you get a bounce saying the message is too large, send a smaller file or ask what their limit is.
Questions
What is the Gmail attachment limit?
25 MB per message for personal accounts. Because of encoding, aim for about 18 MB of real attachments.
What is the Outlook attachment limit?
Outlook.com allows 20 MB. Company mail depends on the server; older Exchange setups default to 10 MB.
Why did Gmail say my 20 MB file is over 25 MB?
Email encoding makes files about a third larger in transit, so 20 MB becomes roughly 27 MB.
Are my files uploaded when I compress them here?
No. Everything on Nearlimit runs in your browser; the file never leaves your device.
Related tools
Email providers change their limits. Gmail's figure was checked against Google's help centre and Outlook's against Microsoft support in September 2026. Nearlimit is not affiliated with Google or Microsoft.