Email Attachment Size Limits by Provider
Quick answer
| Provider | Send limit | Larger files via |
|---|---|---|
| Gmail | 25 MB | Google Drive link |
| Outlook.com | ≈ 20 MB | OneDrive |
| iCloud Mail | 20 MB | Mail Drop (up to 5 GB) |
| Yahoo Mail | 25 MB | Cloud link |
| Proton Mail | 25 MB (total message) | — |
How the limit is counted
Every cap in the table applies to the whole message, not to each file. Four 6 MB photos on one Gmail message add up to 24 MB and squeak through; a fifth one does not. Proton makes this explicit by quoting the limit for the total message, body text included, and the other providers behave the same way in practice.
There is a second reason a file that looks small enough can still bounce. Mail is transported as text, so binary attachments are encoded on the way out and grow by roughly a third in transit. Providers differ on whether they count the raw size or the encoded size, so a 19 MB video sent through a 20 MB account can be refused even though the number on disk looks fine. Leave a margin rather than filling the cap to the last megabyte.
| Total attachments | Safest move |
|---|---|
| Under 10 MB | Attach directly. Works on every provider in the table and most corporate servers. |
| 10 – 20 MB | Attach, but shrink anything you can first; the recipient's server may be stricter than yours. |
| 20 – 25 MB | Only Gmail, Yahoo and Proton accept this much. Outlook.com and iCloud Mail will refuse it. |
| Over 25 MB | Share a link: Google Drive, OneDrive, or Mail Drop (iCloud, up to 5 GB). No provider listed here accepts a larger attachment. |
Documents and scans
Scanned PDFs are the other common offender: a 20-page scan at 300 DPI can easily reach 30 MB because each page is a full-resolution photo. Compress PDFre-draws each page at a lower resolution and JPG quality in your browser; the trade-off is that the text becomes part of the page image and is no longer selectable, which is fine for a receipt or ID copy but not for a contract someone needs to search. If you must keep the text layer, split the file with Split PDF and send it in parts, or use a link.
When a link is the better answer
Links have a cost of their own: the recipient needs an internet connection to open them, some corporate networks block consumer file-sharing domains, and the file can be changed or deleted after sending. For anything that must be archived with the email itself — invoices, signed forms, evidence — a compressed attachment under 10 MB is the more durable choice. iCloud's Mail Drop is the exception that behaves most like a normal attachment, because Apple Mail downloads it automatically on the receiving side.
File too big? — Compress an image to fit, in your browser.Troubleshooting
- “Attachment size exceeds the allowable limit.”
- Your file is over the provider cap. Compress it, or send a cloud link instead.
- The email sends but never arrives.
- The recipient's server may have a smaller limit. Try under 10 MB or share a link.
- Each file is small but the message is still refused.
- The cap is per message. Add up every attachment, including inline images in a signature, and split the send into two emails if the total is close to the limit.
- A bounce message mentions a size in a different unit.
- Some servers report bytes or kilobytes. 20,971,520 bytes is 20 MB. If the number is lower than the provider's advertised cap, the recipient's organisation has set its own.
Sources
- Send attachments with your Gmail message — Google · verified 2026-06-19
- Insert or attach files in Outlook.com — Microsoft · verified 2026-06-19
- Use Mail Drop to send large attachments — Apple · verified 2026-06-19
- Attach and download files in Yahoo Mail — Yahoo · verified 2026-06-19
- Proton Mail size and rate limits — Proton · verified 2026-06-19
Last verified · reviewed occasionally.
Change history
- — Initial publication with provider sources.