Local Processing · FFmpeg WASM · No Upload
Video Compressor
Reduce video file size directly in your browser. Choose a target size, compress your browser-decodable video, compare the result, and download the smaller file — all processed locally, never uploaded.
video-compressor v2.0
1 Target size
This is a bitrate-based estimate, not a visual quality measurement. Actual results depend on resolution, frame rate, motion, detail, and source content.
Show compression log
Compress a video in four steps
Upload, pick a target, compress, download. Every byte stays on your device.
Upload video
Drop a file up to 10 MB. It is read from a local object URL, never uploaded.
Pick a target
5, 10, 25, 50 MB presets or custom. The tool estimates bitrate and quality instantly.
Compress
H.264 re-encode with a calculated bitrate, audio at 128 kbps, faststart MP4 output.
Compare & download
See real original, compressed, saved and reduction stats, then download.
Precision, privacy, and predictability
What the compressor does with your video — and what it deliberately does not.
Zero upload
FFmpeg WASM runs in a worker inside your browser. Your uploaded video is processed locally and is not sent to a video-processing server.
Smart bitrate
Total bits are divided by duration, 128 kbps is reserved for audio, and the video bitrate is reduced by a 92% planning factor to leave room for encoding and container overhead.
Honest reporting
Actual size depends on content. The tool shows the real original, compressed and reduction stats — no guaranteed numbers.
Which target fits your use case?
Example target sizes and practical use cases.
Email & WhatsApp
When a messaging service has a per-file size limit, choose a target below that limit to make the compressed file easier to send.
Social media upload
Smaller video files can reduce upload time and data usage when sharing videos over mobile or limited connections.
Archive & backup
If a 50 MB video is successfully reduced to 25 MB, that saves 50% of the storage space for that file.
Slow connections
Shareable links that download quickly on patchy Wi-Fi or mobile data. Great for remote teams and field work.
Screen recordings
Raw screen captures are often much larger than they need to be. Compress them for tutorials and bug reports.
Quick drafts
Share rough cuts with clients or collaborators at low bandwidth without waiting for a cloud render.
What it does, and what it does not
Clear boundaries so you know when to reach for another tool.
What it does
- Reduce file size of any browser-decodable video up to 10 MB.
- Target size presets and custom entry with instant quality estimate.
- Smart bitrate calculation with a safety margin.
- Show real original, compressed, saved and reduction stats.
- Export web-ready MP4 (H.264 + AAC + faststart).
- Process videos locally after the FFmpeg engine has loaded.
What it does not
- Guarantee an exact output size — content complexity varies.
- Handle files above 10 MB — browser memory is the ceiling.
- Maintain perfect quality at very low bitrates (physics of compression).
- Output formats other than MP4 in this tool.
Common issues and fixes
Quick answers to the most frequent problems.
Engine won't load
The FFmpeg WASM engine needs WebAssembly and Web Workers, and its files must not be blocked. Exclude ffmpeg from JS minify/combine/delay in optimisation plugins, or self-host the engine files.
Output is larger than the target
Complex, fast-moving scenes are harder to compress than the estimate assumed. Try a lower target size or a smaller custom value.
Compression fails on long videos
Re-encoding happens in browser memory. Near the 10 MB cap or with long durations, expect more failures. Use a desktop tool for heavy jobs.
Quality looks poor
Below 200 kbps most video starts to show blockiness. If your target forces the tool there, raise the target or use a dedicated encoder at fixed quality.
Frequently asked questions
Honest answers about the Video Compressor.
Is my video uploaded to a server?
No. The FFmpeg WASM engine runs entirely in your browser. Your video is read from a local object URL, re-encoded in memory, and never transmitted to AllInOneTools or any third party.
Is the target size guaranteed?
Not exactly. The tool calculates a bitrate designed to land at or under the target, but actual size depends on video complexity. Simple static scenes compress smaller; fast motion and detail may exceed the target slightly. The tool reports the real result honestly.
How is the bitrate calculated?
Target bits are divided by duration, 128 kbps is reserved for audio, and the video bitrate is reduced by a 92% planning factor to leave room for encoding and container overhead.
What quality should I expect?
The tool uses bitrate bands as a rough estimate: around 1500 kbps or more is labelled high, 500–1500 kbps good, 200–500 kbps acceptable, and below 200 kbps poor. Actual visual quality depends heavily on resolution, frame rate, motion, and source content.
Why is there a 10 MB input limit?
Re-encoding happens entirely in browser memory. The 10 MB input limit helps reduce memory pressure, especially on devices with limited resources. For larger files, use a desktop tool like ffmpeg, HandBrake or Shutter Encoder.
Why is the first compression slow?
The FFmpeg WASM engine is about 30 MB and downloads once on first use, then stays cached. Compression time after that depends on video length, resolution, and your CPU.