Compress Video Online: MP4 to a Target Size, No Upload

Make a video small enough to send: choose a quality, or the size limit you need to fit, such as Discord's or Gmail's. The video is compressed on your device and never uploaded.

How to compress a video

Choose a video (MP4, MOV, WebM, MKV, 3GP or TS). Its size, resolution and length appear straight away.
Pick Smaller, good quality and a quality level, or Fit a size limit and the limit. Check the estimated size, and lower the resolution or remove the sound if you need it smaller.
Press Compress video, watch the result, then download the MP4.

How the size limit works

A video's size is its bitrate (bits per second) times its length. To fit a limit, the tool aims for 97% of it, to leave room for the file's own bookkeeping: total bitrate = limit × 8 × 0.97 ÷ seconds. The sound gets 64 to 128 kbit/s of that and the picture the rest. If the picture would get fewer than about 0.045 bits per pixel per frame, Auto steps the resolution down (1080p, 720p, 540p…) so the picture stays sharp instead of blocky. Encoders don't hit a bitrate exactly, so if the file comes out over the limit, it is compressed again at a lower bitrate, up to two more times.

Example

A 1-minute 1080p phone video of 120 MB, with a 25 MB limit: 25,000,000 × 8 × 0.97 ÷ 60 = 3,233,333 bits a second in all. The sound keeps 128 kbit/s, which leaves 3,105,333 bit/s (3.1 Mbit/s) for the picture. That's still about 0.05 bits per pixel at 1920×1080, so Auto keeps full HD, and the estimate is about 23.36 MB. With a 10 MB limit there's room for only 1.2 Mbit/s, so Auto lowers the picture to 960×540 and the sound to 96 kbit/s, for about 9.34 MB.

Tips

Balanced at 1080p suits most phone videos; Smallest file at 720p for long clips.
A silent clip? Tick Remove the sound. A 60 fps video gets noticeably smaller at 30 fps.
Only need part of it? Trim the video first: a shorter video fits a limit at a higher quality.
WhatsApp accepts files up to 2 GB, but it recompresses videos you send in a chat; compressing first just makes sending quicker on a slow connection.

Video files are read and written with Mediabunny 1.61.3 (Mozilla Public License 2.0), loaded unmodified as a separate file, and coded by your browser's own video and audio encoders (WebCodecs). Licence and source code.

Frequently asked questions

Is my video uploaded?

No. The video is read and re-encoded by your browser's own video encoder on your phone or computer, so nothing is sent to a server, and there is no upload to wait for.

How small can a video get?

File size is bitrate × length. A 1-minute video under 25 MB can use about 3.2 Mbit/s, enough for full HD; under 10 MB it gets about 1.3 Mbit/s, so Auto lowers it to 960×540. Long videos need a bigger limit, a lower resolution, or trimming first.

Will the quality drop?

Some detail is always lost when a video is compressed. Better quality keeps the most; Smallest file and low size limits soften fine detail. Each round of compression loses a little more, so keep your original and compress a copy.

What size should I choose for Discord, Gmail or Outlook?

Discord accepts files up to 20 MB on a free account and Gmail sends up to 25 MB of attachments. Outlook allows 20 MB per email in total, and attachments grow by about a third when they are sent, so aim for about 14 MB there. Limits checked on 7 October 2026.

Which browsers can compress video?

Chrome, Edge, Opera and Samsung Internet on Android and computers, Safari 16.4 or later on iPhone, iPad and Mac, and Firefox 130 or later on computers. Firefox for Android can't encode video yet. Browsers without an H.264 encoder make a WebM file instead of an MP4.

Is there a size limit?

Files up to 2 GB can be opened. The compressed video is built in your device's memory, so very long 4K videos are best done on a computer rather than a phone.

Can't find the tool you need? Tell us, and the most requested tools get built first.