Email Attachment Size Limits: Gmail, Outlook, Yahoo and iCloud
Every provider publishes an attachment limit, and the number you actually get is lower than the one advertised. Here is what each major service allows, the encoding quirk that eats roughly a third of your headroom, and the practical alternatives when a file will not fit.
Limits by Provider
Most major email providers cap attachments at around 25 MB, and the usable figure is closer to 18 MB once the message is encoded for transmission.
| Provider | Stated attachment limit |
|---|---|
| Gmail | 25 MB (larger files are offered as a Drive link instead) |
| Outlook.com | 20 MB via the web, higher for some desktop configurations |
| Yahoo Mail | 25 MB |
| iCloud Mail | 20 MB, with Mail Drop offered above that |
| Corporate Exchange | Set by an administrator, often 10–35 MB |
Treat these as approximate. Providers adjust them, and an administrator can set anything they like on a business account. Check your provider's current documentation before relying on a specific number.
Why Your Real Limit Is Lower
A 24 MB file frequently bounces against a 25 MB limit, and the reason is encoding rather than the file itself.
Email cannot carry raw binary data, so attachments are encoded into text using Base64. That encoding inflates the payload by roughly 33%. A 20 MB file becomes about 27 MB on the wire — over a 25 MB cap despite appearing comfortably under it.
The rule of thumb: your usable attachment limit is about three quarters of the stated one. Against a 25 MB cap, files under roughly 18 MB are safe.
Message headers, the body, and any signature image add a little more on top.
Send a Link Instead of an Attachment
Create a share link in seconds — no size cap to work around, and it expires on your schedule.
The Recipient's Limit Matters Too
Your provider's limit governs whether the message sends. The recipient's governs whether it arrives — and a message rejected at their end may bounce hours later, or silently vanish into a quarantine neither of you checks.
This is the common failure behind "I sent it, did you get it?":
- You send a 22 MB attachment from a provider allowing 25 MB.
- Their corporate mail server caps inbound messages at 10 MB.
- The message is rejected or quarantined on arrival.
You cannot know the recipient's limit in advance, which is the strongest argument for not attaching large files at all. A link is a few hundred bytes and passes every mail server on earth.
What to Do When It Will Not Fit
Send a link instead of an attachment
Upload the file once and email a link to it. The message stays tiny, neither mail server's attachment cap applies, and you can set the link to expire so the file is not left online forever. Create one at getfileshare.cloud/upload — uploads have their own per-file ceiling, which the page states before you choose a file.
Compress it, if it will actually compress
Documents, spreadsheets and text compress well in a ZIP archive. Photos, video and audio are already compressed and will barely shrink — a ZIP of a video is close to a waste of time.
Transfer directly, if the recipient is available now
For a file going to someone you are already talking to, skip email entirely: they open getfileshare.cloud/receive and you send it from getfileshare.cloud/send. Nothing is stored anywhere, and the only ceiling is the per-file limit.
Split the file
Archive tools can split a large archive into fixed-size parts. It works, and it asks the recipient to reassemble them — usually the least pleasant option for whoever is receiving.
Frequently Asked Questions
What is the maximum attachment size for Gmail?
Gmail caps attachments at 25 MB. Because attachments are Base64-encoded for transmission, which adds roughly a third to the size, files above about 18 MB frequently fail against that cap. Attaching something larger prompts Gmail to upload it to Drive and send a link instead.
Why is my 20 MB file rejected by a 25 MB limit?
Email encodes attachments as Base64 text, inflating them by around 33%. A 20 MB file becomes roughly 27 MB in transit, which exceeds a 25 MB cap even though the file on disk is well under it.
How do I send a file larger than 25 MB by email?
Send a link rather than an attachment. Upload the file once, paste the link into your message, and the email stays small enough for every mail server in the path. This also sidesteps the recipient's own inbound limit, which you have no way of knowing.
Does compressing a file help it fit under the limit?
It depends entirely on the file type. Documents, spreadsheets and text often shrink substantially in a ZIP. Photos, video, audio and PDFs are already compressed, so a ZIP typically saves a few percent at best — not enough to bring a large file under a cap.