Compress Video for Email Fit Gmail's 25 MB attachment limit
Gmail's attachment limit is 25 MB, and Google documents that figure as the total size of your message content and attachments before encoding, so it is measured against the file as it sits on your disk. A 24 MB video attaches and sends. The catch arrives later. Once the message leaves, the attachment travels as base64 text that runs roughly a third larger, and the mailbox at the other end measures that larger version. Google's own receiving limit is documented at 50 MB after encoding, so Gmail to Gmail has room to spare. A stricter work server may not. This page opens with an 18 MB target for that reason, because 18 MB encodes to around 25 MB and clears the receiving limits you are most likely to meet. Everything is encoded on your own machine, so the file makes one trip, when you send it.
- 18 MB target
- Nothing uploaded
- Up to 20 videos
Drop videos or browse your device
MP4, MOV, M4V, MKV, AVI, WebM, WMV, TS, MTS, MPEG, 3GP, FLV and more
Up to 20 videos at once
Your video is processed in your browser's memory and never uploaded, so the ceiling is set by your device, not by us.
Aims for 18 MB at 720p, the size that still arrives when you do not know the recipient's mail server. Gmail itself accepts up to 25 MB.
Privacy-first. No uploads. If this helps, share it.
Bigger files? Run it in the Cloud
This tool runs on this device for free. For a file over the device limit or a long video, the same tool runs on our servers, with up to 5 GB per file and 6 hours of video, faster, and with your files kept for up to 7 days, or as long as you choose with any pack or plan. From 1 credit a minute, with 10 credits free when you create an account.
- The video never leaves your device
Compression runs on your own machine, inside this tab, through a WebAssembly build of FFmpeg. The only copy that goes anywhere is the one you attach to your own message, which matters when the video is a property walkthrough, a medical clip, a client deliverable or a family recording.
- Targets the size that arrives
The page opens on the Email goal, which aims for 18 MB. That is not Gmail's limit: Gmail accepts up to 25 MB and measures it before encoding, so a 24 MB file attaches happily. 18 MB is the conservative figure, because the server at the other end measures the encoded message and sees about a third more. A bitrate ceiling is worked out from the video's own duration and the encoder aims under it. If you know the recipient is on Gmail or Workspace, one click switches the target to 24 MB.
- 20 videos per batch, 1.75 GB each
Prepare a set of clips for one message, or several messages in one sitting. The queue works through videos one at a time, since the browser build uses a single thread, and each result can be saved on its own or with the rest as a zip.
How to compress a video for Gmail
Gmail's published limit is 25 MB, and Google documents it as the size before encoding, so a file just under 25 MB attaches. What that limit does not cover is the receiving server, which measures the encoded message and sees roughly a third more. Add your video, leave the target at 18 MB when you do not know where it is going, and raise it toward 24 MB when you know the recipient is on Gmail or Google Workspace.
- Add the video
- Keep the 18 MB target
- Attach the smaller MP4
What Gmail and other mail services accept
Two numbers matter here, and they are measured with different rulers. Gmail's sending limit counts your message and its attachments before encoding, so it lines up with the size on your disk. Receiving limits count the encoded message, which runs roughly a third larger. That gap is why the right target depends on who you are writing to.
| Service or path | Published limit | What it means |
|---|---|---|
| Gmail, sending | 25 MB | Google documents this as the total of message content and attachments before encoding, so it is the size on your disk. Your body text, signature and any inline images come out of the same 25 MB, so leave a little headroom. |
| Gmail and Workspace, receiving | 50 MB | Documented for Workspace Enterprise Standard and measured after encoding, which Google puts at about a 37 percent increase. A full size Gmail attachment lands inside it. Google does not publish a receiving figure for personal Gmail accounts. |
| Outlook.com | 25 MB | Microsoft publishes the same 25 MB for files attached in Outlook.com. The Outlook desktop app is a separate thing and defaults to 20 MB for internet email accounts, which is where the lower figure in most guides comes from. |
| Typical corporate mail server | Often 10 to 36 MB, encoded | Set by the recipient's administrator and applied to the encoded message. Microsoft 365 mailboxes default to about 36 MB received, which a full size Gmail attachment clears. A self managed Exchange server ships with a 10 MB default, which it does not. If the address is a work domain whose rules you do not know, compress smaller. |
| Google Drive link fallback | Your Drive storage | What Gmail switches to when your message and attachments add up to more than 25 MB. The file goes to Drive and the message carries a link, with sharing permissions the recipient may have to request. |
Providers move these numbers and administrators override them, so read the table as a snapshot rather than a promise. Checked against Google's and Microsoft's own pages on 16 August 2026.
Why 25 MB on disk is not 25 MB on the wire
Email was built to carry text, so every attachment is re-encoded into plain characters with base64 before it is sent. Base64 turns every three bytes into four, a 33 percent increase on its own, and the line breaks and MIME headers around it push the real figure closer to 37 percent. The part most guides get backwards is which end applies that. Google states its 25 MB sending limit is measured before encoding, so at compose time Gmail is looking at the file on your disk. The receiving server is the one that measures the encoded message. Google's own mailboxes are documented to take 50 MB after encoding, which is comfortably more than a 24 MB attachment turns into. Servers you do not control are the risk, and 18 MB on disk encodes to around 25 MB, which is the figure most of them are set to.
Your message body, your signature and any other attachments come out of the same total at both ends, so aim a little under the ceiling rather than at it.
On the Gmail app the swap is easy to miss
The Gmail apps for Android and iOS apply the same 25 MB total as the web, and they deal with an oversized video the same way: the file goes to your Google Drive and the message carries a link. On a small screen that substitution is easy to miss, because the compose screen still shows a video and the message sends without complaint. The person at the other end gets a link, sometimes one they have to request access to, and you find out when they reply asking for the file.
Open the message in Sent rather than trusting the compose screen. A real attachment appears with its file size, a Drive link appears as a link.
Phone video is the usual culprit. A minute of 4K from a recent phone can run to several hundred megabytes, so it is nowhere near the limit before compression.
Compressing before you attach settles it, because the file Gmail measures is already small enough.
Get a video under the limit in three steps
Three steps, and none of them is an upload.
Add your videos
Drag videos in or browse your device. MP4, MOV, MKV, AVI and WebM are accepted, 20 files per batch and 1.75 GB per file, which covers phone recordings, screen captures and camera exports.
Keep the 18 MB target
It is already filled in under Custom, with a quality slider and a resolution choice beside it. Writing to a Gmail or Google Workspace address, you can raise it toward 24 MB. Writing to a work domain whose rules you do not know, try 9 MB.
Download it, then attach it
You get an H.264 MP4 with AAC audio, which plays in every mail client and on every phone. Check the size on the result card, then attach that file rather than the original.
Why bother, when Gmail offers the Drive link anyway
The Drive fallback is convenient for Google, and it is genuinely fine for some messages. It is a poor substitute in more situations than people expect.
A link is not a file
A Drive link depends on sharing permissions, on the recipient signing in with the right account, and on the file staying where you left it. Move it, tidy your Drive months later, or leave the company, and the link in that thread stops working. An attachment sits in the mailbox for as long as the mailbox does.
Mail filters are wary of links
Some company mail gateways flag or strip links to consumer file hosts, and a few block them outright as a data loss precaution. A modest attachment often walks straight through where a Drive link gets quarantined.
The recipient's limit is not your limit
Gmail will take 25 MB from you, but the mailbox at the other end measures the encoded message and may only accept 10 MB of it. Those rejections come back hours later as a delivery failure notice that is easy to skim past. Compressing to a smaller target is the simplest way to clear both ends in one pass.
You cannot eyeball the number that matters
Nothing in a file browser tells you what a video will weigh once it is encoded for email, and Gmail only reacts after it has finished taking the file in. Setting a target first turns a guess, a silent Drive link and a second attempt into one pass.
Just need a size number rather than an email preset? Compress video under 25 MB.
Not sending the picture at all? Extract the audio as MP3 instead, which is far smaller than any video.
Email attachments tend to be the private ones
The videos people compress before emailing are insurance claims, property walkthroughs, clips for a specialist, job application recordings, evidence for a dispute and family video going to one relative. Sending that to a stranger's server first, only to make it smaller, gives away more than it saves.
The work here is done by a WebAssembly build of FFmpeg running in the page. There is no transfer, no queue on someone else's machine, no retention policy to read and no sign in that could tie the file to a name. When the tab closes, the only compressed copy is the one in your downloads folder.
What that means in practice
- The video is sent once, by you, to your recipient
- The file and its name stay on your own machine
- No account, no watermark, no upsell on the output
- The work runs on your own processor, so a long video takes time
Gmail attachment troubleshooting
Compress for a specific place
Some places have a hard size limit and a few quirks of their own. These pages open the compressor already set to that target, and explain what the limit actually is.
- WhatsApp Video Compressor
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Open toolFrequently asked questions
Gmail publishes 25 MB for messages you send, and Google documents that as the total of your message content and attachments before encoding, so it maps to the size on your disk. For receiving, Google documents 50 MB after encoding on Workspace Enterprise Standard and 70 MB on Enterprise Plus. It does not publish a receiving figure for personal Gmail accounts.
Attachment limits were checked against Google's and Microsoft's own help pages on 16 August 2026.