How does Target File Size (MB) work?

The engine calculates the required video bitrate in bits per second from your video's duration, encodes at that bitrate, and then checks the actual generated file size—reporting honestly whether the target MB was met.

Does compressing a video remove audio?

No. Audio is preserved alongside the compressed video track.

Video Compressor

Shrink MP4, MOV, and WebM video file size locally in your browser by adjusting encoder quality, capping resolution (1080p, 720p, 480p), or setting a target file size in MB.

Drop an MP4, MOV, or WebM video to compress locally

Adjustable bitrate quality, resolution downscaling, and verified target-MB budgeting

Zero server upload · Files never leave your device

COMPRESSION SETTINGS

Compression quality presetMaximum resolution heightOptional target file size (MB)

MB

Calculates target video bitrate from duration and verifies actual generated byte size.

COMPRESSED OUTPUT & VERIFIED SIZE

Load a video above to compress and inspect verified file-size reduction.

Loading tool workspace…

Method and assumptions

Videos are re-encoded locally using Mediabunny's quality presets or an explicit target bitrate derived from your requested file size in megabytes: targetVideoBps = (targetMB × 8 × 1024² × 0.92 / durationSeconds) − audioBps. After muxing completes, the actual generated Blob byte size is measured and compared against your target MB.

Common mistakes and edge cases

Hardware encoders enforce a minimum bitrate floor for a given resolution and frame rate. If a very small target MB cannot be reached at 1080p/4K without dropping below the encoder floor, the tool reports the exact achieved MB and recommends lowering the resolution cap.

How to use

Drop an MP4, MOV, or WebM video into the workspace (or load the 3-second sample clip).
Select a Compression quality preset and optional Maximum resolution height.
Optionally enter a Target file size in MB to compute a target video bitrate.
Click Compress video, inspect the verified output size and percentage reduction, and click Download.

Example

Load a video clip, choose the Compact quality preset or enter a target size in MB, optionally cap resolution at 720p, and inspect the verified before/after byte savings.

Frequently asked questions

How does Target File Size (MB) work?: The engine calculates the required video bitrate in bits per second from your video's duration, encodes at that bitrate, and then checks the actual generated file size—reporting honestly whether the target MB was met.
Does compressing a video remove audio?: No. Audio is preserved alongside the compressed video track.

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This tool is provided for general informational and workflow purposes only. It does not constitute financial, investment, tax, or professional advice. All calculations run in your browser; no input data is transmitted or stored.