Compress preset

Compress Video for Email

18 MB targetGmailH.264 MP4

Email still trips on video attachments. Gmail stops at 25 MB of total message size, and because attachments are base64 encoded on the way out, that leaves room for about 18 MB of actual video. Outlook.com caps the message at 20 MB, which fits about 14 MB of video. Corporate Exchange servers often enforce 10 MB at the gateway. The buttons above the size field are set to the raw video size that fits each cap, not the cap itself, so the message does not bounce.

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Compressing for Email in detail

The output is standard MP4 with H.264 video and AAC audio, so the file opens the moment your recipient clicks it. No plugins, no codec installs. The encoder works out a bitrate from your target and the clip length and encodes in one pass, so the result lands near the target. A one to two minute clip at 18 MB still looks good at 720p. For a five minute clip you will want to trim first or accept a softer picture.

Privacy matters in email more than most channels. Signed quotes, client onboarding walkthroughs, and medical intake videos often end up attached to messages. Running the compression locally means the source file never leaves your machine during the process. The only copy of the compressed MP4 goes where you send it.

Attachment limits by mail provider

Setting	Value	Notes
Gmail	25 MB per message	About 18 MB of raw video after base64 overhead.
Outlook.com	20 MB per message	About 14 MB of raw video after encoding.
Microsoft 365 business	Admin-controlled, up to 150 MB	Defaults vary by tenant. Ask IT before assuming more than 20 MB.
Corporate Exchange	10 to 25 MB	Varies by IT policy; 10 MB is a common gateway default.
ProtonMail Free	25 MB per message	Same ceiling as Gmail on the free tier.
Apple iCloud Mail	20 MB per message	Larger attachments go out as a Mail Drop link from the Mail app.

When to use this preset

Client onboarding walkthroughs

Record a three minute product walkthrough and fit it into 18 MB so new customers watch it in Gmail without a Loom account.

Signed quote explainers

Attach a short screencast explaining the line items of a quote, keep it inside the Outlook cap, and skip the meeting.

Status updates to stakeholders

When a Slack message is not formal enough, a short video attached to an email lands in the inbox as a deliverable with full context.

Support bug recordings

Compress a 1080p OS-level screen recording down to 10 MB so it passes through strict corporate mail gateways on the first try.

HR and legal evidence clips

Keep a clip as an email attachment for an audit trail; under 20 MB is small enough to archive and clear enough to review later.

Frequently asked questions

What is the maximum video attachment size for Gmail?

Gmail allows messages up to 25 MB in total, counting the body, headers, and every attachment after base64 encoding. Base64 inflates binary data by about a third, so roughly 18 MB of raw video fits. That is why the default target on this page is 18 MB rather than 25.

How do I email a large video?

You have two choices. Either compress the video to fit your provider's cap using this tool, or upload it to a cloud link like Google Drive and paste the share URL into the email. Compression keeps the video as a true attachment, which recipients treat as part of the message, while a link gives them one more thing to click.

What is the Outlook attachment size limit?

Outlook.com personal mailboxes limit the message to 20 MB, which fits about 14 MB of raw video. Microsoft 365 business tenants can be configured up to 150 MB, but many stay near the default. Corporate Exchange gateways often enforce stricter caps, sometimes 10 MB, regardless of what the Outlook client shows.

Can I send a video larger than 25MB in Gmail?

Not as a direct attachment. Gmail prompts you to upload the file to Google Drive and sends a share link instead. If you want a true attachment, compress the video to 18 MB or less so the encoded message stays within the 25 MB transport limit.

What format should I send video in email?

MP4 with H.264 video and AAC audio. Every modern mail client previews MP4 inline, and every operating system plays the file with the default media player when the attachment is saved. Avoid MOV for Windows recipients, MKV for any recipient, and WMV for anyone on a Mac or phone.

Does email compress video attachments?

No. Mail servers do not re-encode attachments. They forward the bytes as-is and enforce the total message size limit before delivery. That means the 30 MB video that failed to send will still be 30 MB at every hop. Compressing client-side is the only way through.

Why was my video email rejected?

Almost always because the total message exceeds the recipient's mail server limit. Even if your outbound server accepts the message, the receiving server may reject it. When in doubt, compress to the conservative 10 MB target, which fits nearly every corporate Exchange policy in the wild.