How to send a large video by email

Email attachment limits are the most misleading numbers in this whole subject, because the number the provider publishes is not the number your file has to come in under.

Get that one fact right and the rest is straightforward.

The published limits, and the real ones

Email cannot carry raw binary data. Attachments are base64-encoded for transport — every three bytes of file become four characters of text — which inflates them by about 33%. The published limit applies to the encoded message, not to the file on your disk.

Provider	Published limit	Keep the file under	Why
Gmail	25MB sending	~18MB	25MB cap is on the base64-encoded message
Outlook.com	20MB	~15MB	Same encoding overhead, measured after MIME
Exchange / Microsoft 365	Set per organisation	Often 10MB	Administrators routinely lower the default

So a 24MB video that looks like it should sneak under Gmail's 25MB becomes a roughly 32MB message and bounces. The bounce message will tell you the attachment was too large, having given you no way to work out by how much.

The arithmetic, if you want to check your own number:

file size × 1.33 ≈ message size

18,000,000 × 1.33 = 23,940,000    clears Gmail's 25MB
25,000,000 × 1.33 = 33,250,000    does not

The dated figures live on the Gmail limit page and the Outlook limit page, each with a link to the provider's own documentation.

One more wrinkle on corporate mail: the recipient's server has a limit too, and it is often lower than yours. A 15MB attachment that leaves your Outlook happily can be rejected by the receiving Exchange server with no notification to you at all. If a message to a specific company keeps vanishing, that is usually why.

Option 1 — compress the video to fit

The best option when it works, because the recipient gets a real attachment rather than a link they have to trust, click and keep alive.

For most clips this is entirely practical. An 18MB budget holds:

• A 2-minute clip at 1080p (about 1.1 Mbps — above the 1080p floor)
• A 5-minute clip at 720p (about 450 kbps — tight, but 480p is a comfortable fallback)
• A 10-minute clip at 480p
• A 30-minute clip at nothing watchable — see option 2

Compress to 18MB for Gmail or to 15MB for Outlook. Both presets target the real ceiling rather than the published one, run entirely in your browser with nothing uploaded, and measure the finished file to confirm it is actually under the limit before handing it to you.

If you are unsure whether your clip can fit, drop it in — the page tells you the resolution and bitrate you would get, before spending any time encoding.

Option 2 — trim before you compress

If the clip is long, this is not a lesser option. It is the correct one.

Size is bitrate multiplied by duration, so a 30-minute video into 18MB means roughly 80 kbps for picture and sound together. Nothing watchable exists at that bitrate, and any tool that accepts the job anyway is going to hand you a smear. Cutting to the 90 seconds that actually matter gets you 1.6 Mbps and a genuinely good-looking 1080p clip.

The fastest trim is usually the one already on your device: QuickTime on macOS (⌘T), the Photos app on Windows, or the built-in editor in your phone's gallery. All of them trim without re-encoding, so the cut is instant and lossless.

Option 3 — send a link instead

Upload to Google Drive, OneDrive, Dropbox or WeTransfer and email the link. Gmail offers this automatically when an attachment is too big, inserting a Drive link in place of the file.

The trade-offs are real and worth being deliberate about:

• The file is uploaded to a third party, which may matter for anything confidential.
• WeTransfer links expire, typically after seven days.
• Drive and OneDrive links depend on sharing permissions being right, which is the single most common reason a recipient reports "I can't open it".
• Some corporate mail filters strip or flag external file-sharing links more aggressively than attachments.

Good for very large files and for recipients you know. Worse than an attachment for anything that needs to still work in six months.

Option 4 — a shared folder, for recurring sends

If you send video to the same person regularly, a shared Drive or OneDrive folder removes the problem permanently: drop the file in, and they already have access. No link, no limit, no permission dialog each time.

What to do, in order

1. Under about 18MB already? Attach it. Nothing to do.
2. Over, but a few minutes or less? Compress it to 18MB. It will almost certainly still look good.
3. Long? Trim first, then compress.
4. Genuinely needs to stay long and large? Send a link, and check the sharing permissions before you hit send.

FAQ

What is the maximum video size I can email?

Treat it as about 18MB for Gmail and about 15MB for Outlook.com, for the file as it sits on your disk. The published limits of 25MB and 20MB apply to the base64-encoded message, which is roughly a third larger than the file itself. Corporate Exchange servers are frequently configured lower, so 10MB is the safer assumption for business addresses.

Why did my 24MB video fail to send on Gmail when the limit is 25MB?

Because Gmail measured the encoded message, not the file. Base64 encoding added about a third, making your 24MB attachment roughly a 32MB message — well over the 25MB cap. Compressing the file to 18MB or less resolves it.

Does zipping a video make it small enough to email?

No, and it is worth knowing why: video is already compressed, heavily and with a lossy codec designed for exactly this data. A ZIP wrapper around an MP4 typically saves under 2% and sometimes makes the file slightly larger. It also means the recipient has to unzip before they can watch. Re-encoding the video is the only thing that meaningfully changes its size.

Can I send a large video without uploading it anywhere?

Yes — compress it so it fits as an attachment. The compressor on this site runs in your browser using your own machine's hardware encoder, so the video is never uploaded to us or to anyone else. See compressing video without uploading it for how that works and why it is usually faster than a link.