Compress Video
Compress Video re-encodes a clip so the file is smaller while the picture stays as close to the original as possible. You choose how hard to compress and, if you want, cap the resolution; the encode runs on your own device with FFmpeg compiled to WebAssembly, and the result downloads straight back to you. Nothing is uploaded.
Add your video
The file is read by your browser and stays on your device — there is no upload step.
Your video
The work runs in this tab. Nothing is sent anywhere, and the download is generated locally.
How to use Compress Video
- 01Upload
Add your video
Drop an MP4, MOV, WEBM, MKV or AVI file in, or click to browse. The current size is shown so you know your starting point.
- 02Customize
Choose a quality preset
Higher quality, Balanced or Smallest file. Each sets how aggressively the encoder discards detail — Balanced is the right default for most footage.
- 03Process
Cap the resolution if you need to
Leave it at the source, or cap the height at 1080p, 720p or 480p. This is the biggest single saving, and the video is never upscaled.
- 04Download
Export and download
The encode runs locally with live progress. When it finishes you see the old size, the new size and the percentage saved, then download.
What are you compressing for?
Video size is dominated by bitrate, and the right bitrate is decided by where the clip is going and how much motion it contains.
- Email or chat720p, low bitrate
Attachment limits are usually 10–25 MB. Dropping to 720p roughly quarters the pixel count before the encoder even starts, which does more than any quality slider.
- Social upload1080p, medium
The platform will re-encode whatever you send. Sending a huge file mostly costs you upload time — it does not survive to the viewer.
- Archivehigh, or don't
For anything you will edit again, compress as little as possible. Re-encoding an already-compressed file compounds the loss and cannot be undone.
What changes, and what does not
Bitrate, and with it the detail in motion. Compression artefacts show first in grain, water, foliage and fast pans — anything where a lot of pixels change between frames.
Resolution, frame rate, duration and audio unless you change them yourself. A compressed 1080p clip is still 1080p.
The settings that actually matter
- Bitrate
Data per second of video. This is the main lever — halve it and you roughly halve the file. Too low and the picture blocks up in motion.
- Resolution
Fewer pixels means less to encode. Going 1080p to 720p is usually a bigger saving than any amount of quality tuning, and on a phone it is hard to see.
- Codec
H.264 plays everywhere. H.265 is meaningfully more efficient for the same quality but is slower to encode and not universally supported.
When compression is not the answer
- The clip is simply too longTrim Video
- It is far higher resolution than it needs to beResize Video
- It will not play on the target device at allConvert Video
- Only the audio is actually neededExtract Audio
Supported formats
- MP4
- MOV
- WebM
- AVI
- MKV
- Maximum file size —
- bounded by your device's memory
- Processed by —
- FFmpeg (WebAssembly), on your device
Your file, and what the page does
Your file is never uploaded. Compress Video reads it into this browser tab and processes it with FFmpeg compiled to WebAssembly on your own device. There is no upload endpoint in the application and no copy on any server — closing the tab discards it.
That is also why processing takes longer here than on a site that uploads: your device is doing the work rather than a rack of servers. The trade is that the file never leaves it.
What the page does send or fetch
- The processing engine, once
- The first time you use any video or audio tool, the browser downloads the FFmpeg WebAssembly build (~30MB) from the jsDelivr CDN and reuses the cached copy afterwards. That is a file coming to you — no part of your own file is in the request.
- Ads on the page
- The site is funded by advertising, so the page loads Google AdSense. That carries the usual web basics — IP address, browser, referring page — as on any ad-supported site.
- An anonymous usage counter
- When Compress Video finishes we record that the tool ran, whether it succeeded and how long it took. No file data, no identifier, no cookie.
Your file is not on that list. How this works.
Frequently asked questions
It depends almost entirely on the source. Footage straight off a phone or camera usually compresses a great deal; a file that has already been compressed once has much less left to remove. The tool shows the before and after size after every run, so the answer for your specific file takes one export.
Some detail is discarded — that is how the file gets smaller. At Higher quality the difference is very hard to see on normal footage. At Smallest file it becomes visible in fast motion, grain and fine texture, which are the hardest things to encode.
Usually, yes. Going from 1080p to 720p removes about 55% of the pixels in every frame, which is a larger and more predictable saving than pushing the quality preset one step harder — and it often looks better than the equivalent quality drop at full resolution.
No. The frame rate is passed through untouched, so a 60fps clip stays 60fps and motion looks exactly as it did. Only the resolution and the encoding quality change.
Not with this tool. Re-encoding is lossy by definition. If you need a genuinely lossless result the only options are to trim the clip shorter or leave it alone — but at Higher quality the loss is small enough that most people cannot see it.
It has to decode every frame, transform it and encode it again — the most CPU-intensive job on the site — and the browser build of FFmpeg runs on a single thread. Trimming, rotating and muting only touch part of the file, which is why they finish in seconds.
Yes — Compress Video is completely free. There's no account, sign-up, watermark or limit.
No. It runs in any modern browser — Chrome, Edge, Safari, Firefox, Brave — with nothing to download or install.
Not sure compressing is what you need?
- Too large to send, and it is the right lengthCompress Video
- Too long — only part of it mattersTrim Video
- Higher resolution than the destination usesResize Video
- Will not play where you need itConvert Video
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