Video Size Limiter
Compress a Video to a Precise File Size
Need to use Video Size Limiter right now?
Works backward from your target size, subtracting a fixed audio bitrate before calculating video bitrate.
Drop a video file, or click to browse
Processed locally in your browser — never uploaded
Calculates the exact video bitrate needed to hit your target size given the video's duration, then encodes at that bitrate — actual size lands close to, not always exactly at, the target due to single-pass encoding variance.
Features
- Privacy-first processing with automatic deletion
- Real-time, instant results
- 100% free, no sign-up required
- Works on desktop, tablet, and mobile
- No installation needed
Who uses this tool?
About Video Size Limiter
Many upload forms and platforms cap file size at a hard limit — a 25MB email attachment, a 100MB submission portal — and knowing what quality setting will actually land you under that limit is mostly guesswork with a generic compressor. This tool works backward from your target size instead: tell it the size you need, and it calculates the exact bitrate required.
The math is straightforward but precise: your target size in megabytes converts to a total bit budget, the video's actual duration (read automatically from the uploaded file) determines how that budget spreads across the timeline, and a fixed audio bitrate (128kbps) is subtracted first so the remaining budget goes entirely toward video quality at the calculated bitrate.
A real FFmpeg build compiled to WebAssembly runs the compression entirely inside your browser using this calculated bitrate, encoding with the fast "veryfast" preset since single-pass bitrate-targeted encoding doesn't need the extra encoding passes a maximum-efficiency encode would use.
Because this uses single-pass encoding (rather than a slower two-pass approach that can hit an exact target more precisely), the actual result typically lands close to your target size but not always exactly at it — variance depends on how much the video's content complexity varies over its length. The exact resulting size is shown after compression so you know precisely where it landed.
How it works
- Upload your video. Duration is detected automatically.
- Set your target size in MB. The required bitrate is calculated from size and duration.
- Compress and download. See the exact resulting size once it's done.
Examples
Meeting an email attachment limit
Input
video compressed with a 10MB target
Output
a file landing close to 10MB, ready to attach