Video Compressor
Shrink MP4 and MOV videos to a size or quality you pick. Runs in your browser.
About this video compressor
This video compressor makes MP4, MOV, WebM and MKV files smaller by re-encoding them with your browser's own video encoder. Use it to get a clip under an upload limit, send it by email, or free up space without leaving a watermark on the result.
Your video is never uploaded. Encoding runs on your device, usually on the graphics chip, so there is no upload wait, no file size cap and no queue.
You can pick a quality preset, or type a size in megabytes and let the tool work out the bitrate from the video's length. Resolution, frame rate, codec and audio are all yours to set, and you see an estimate before you start.
Features
Target size in MB
Type 20 and the tool divides the size by the duration, keeps 4% back as a safety margin, subtracts the audio and gives the rest to the video. If the target can't fit, it tells you the smallest size that can.
Three honest presets
Smaller, Balanced and High quality set a bitrate from the output resolution and frame rate. Balanced lands near 4.7 Mbps for 1080p at 30 fps with H.264.
Resolution and frame rate
Scale to 1080p, 720p or 480p by the short side, so portrait phone video works too. Cap the frame rate at 60, 30 or 24 fps. Nothing is ever upscaled.
H.264, VP9 or AV1
The tool asks your browser which encoders work at your output size and only offers those. H.264 goes into MP4, AV1 into MP4 and VP9 into WebM.
Keep, shrink or drop audio
Keep copies the soundtrack untouched where the container allows. Or re-encode it at 128, 96 or 64 kbps, or remove it for a silent clip.
Never bigger than the original
If the re-encoded file comes out the same size or larger, you get your original back with a note explaining why. Side-by-side players let you compare before and after.
How to use the video compressor
- 1Add a video. You'll see its size, resolution, frame rate and bitrate.
- 2Choose a quality preset or type a target size, then set resolution, frame rate, codec and audio.
- 3Compress, compare before and after, and download. If it doesn't get smaller you keep the original.
When to use it
Getting under a chat upload limit
Discord's free upload limit is 20 MB at the time of writing. Pick the 20 MB target, compress, and the result lands just under it. For longer clips, drop to 720p.
Emailing a video
Gmail and Outlook.com cap a message at 25 MB. Choose the 25 MB target, or a little less to leave room for the message itself.
Screen recordings
Tutorials and bug reports compress very well because most of the screen stays still. A screen recording at 1080p often shrinks a lot at the Smaller preset, even without lowering the resolution.
Long clips that only need part of the action
Cutting time saves more than any setting. Trim the clip first, then compress what's left.
How is the compressed file size worked out?
Video size is bitrate multiplied by time. Size in megabytes equals the total bitrate in megabits per second, times the duration in seconds, divided by 8. A 2-minute clip at 16 Mbps is 240 MB. The same clip at 2.5 Mbps is 37.5 MB.
For a target size, the tool runs that formula backwards. Twenty megabytes over 60 seconds is a 2.67 Mbps budget. The 4% margin brings that to 2.56 Mbps, and after 96 kbps of audio about 2.46 Mbps is left for video. Hardware encoders don't hit a bitrate exactly, which is what the margin is for.
What is a good bitrate for 1080p?
For upload to a video platform, YouTube recommends 8 Mbps for 1080p at 24 to 30 fps and 12 Mbps at 48 to 60 fps. Those numbers assume the platform will compress again, so they are generous.
For watching or sharing, 3 to 5 Mbps of H.264 looks clean for most 1080p footage. Fast motion, grass, water and confetti need more. Talking heads and screen captures need far less. Below about 2 Mbps, 720p usually looks better than a blocky 1080p, and the tool suggests the switch when your target is that tight.
H.264 vs VP9 vs AV1
H.264 (ITU-T H.264, also called AVC) is from 2003 and plays on every phone, TV and browser. VP9 (Google, 2013) and AV1 (Alliance for Open Media, 2018) are newer and need fewer bits for the same picture. AV1 often saves around a third or more over H.264, though results vary with the content and the encoder.
The catch is playback. Older phones and some smart TVs can't play AV1, and VP9 in WebM is less reliable on Apple devices. Choose H.264 when you don't know where the file will be played. Choose AV1 when you control the player and want the smallest file.
Why didn't my video get smaller?
Phone and camera footage is recorded at a high bitrate, so it shrinks a lot. Videos that were already compressed for the web, like downloads from social sites, are often lean already. Re-encoding them at the same resolution can't save much and costs quality.
The tool caps each preset at 85% of the source bitrate, scaled for any resolution or frame-rate drop, and hands you the original if the result still comes out bigger. To go further, lower the resolution or use a target size.
Why use Mavros
| Mavros | Typical upload sites | |
|---|---|---|
| Upload required | No, encodes on your device | Yes, the whole file |
| File size limit | Your device's memory | 500 MB to 1 GB free |
| Watermark | Never | Common on free exports |
| Exact target size in MB | Yes, with a safety margin | Percent sliders or none |
| Codec choice | H.264, VP9 or AV1 where supported | Usually H.264 only |
| Frame rate cap | 60, 30 or 24 fps | Rare |
| Keeps the original if bigger | Yes | No, you download a larger file |
Tips
- Resolution beats bitrate for big savings. Going from 1080p to 720p cuts the pixels by more than half.
- A 60 fps clip capped at 30 fps needs roughly a third fewer bits for the same look.
- Hardware encoders are fast but vary by device. If one browser gives a poor result, try another; Chrome, Edge and Safari often use different encoders.
- Only need the soundtrack? Extract the audio as an MP3 instead. It is a fraction of the size.
- For still images, use the image compressor instead. Video codecs aren't built for single frames.
Questions
How do I compress a video without losing quality?
You can't fully, because compression removes detail. Use High quality or Balanced at the original resolution and the loss is hard to see. Most of the saving comes from the source having far more bitrate than it needs.
How do I get a video under 20 MB for Discord?
Choose Target size, press the 20 MB button and compress. If the estimate says the target can't fit, trim the clip or remove the audio. For clips over a minute, 720p will look better.
Is my video uploaded?
No. The video is read from your disk, re-encoded by your browser's WebCodecs encoder and saved on your device. Nothing is sent to a server.
Why does it say my browser can't encode video?
The tool needs the WebCodecs VideoEncoder API. Chrome and Edge have it, as do Firefox 130 or later and Safari 17 or later. Update your browser or switch to one of those.
Why are VP9 or AV1 missing from the codec list?
The list shows only what your browser can encode at the chosen size. AV1 encoding is newer and missing on many devices. H.264 is the most widely available.
Why did the result come out larger than the original?
The source was already efficient, so re-encoding couldn't beat it. The tool then gives you the original back. Lower the resolution or set a target size to force a smaller file.
How long does compression take?
It depends on the device. With hardware encoding, a 1-minute 1080p clip often takes from a few seconds to under a minute. A progress bar shows the time left, and you can cancel.