Reduce video file size without false promises

Choose resolution, bitrate and quality settings with realistic expectations about encoding time and visible quality.

Where file size comes from

Duration, total audio-plus-video bitrate, complexity and container overhead determine the approximate compressed size. A simple estimate is size in bytes ≈ duration in seconds × combined bitrate in bits per second ÷ 8. Variable bitrate means actual output can differ.

Best-effort compression

Reducing resolution or bitrate can shrink files but may make fine details softer, increase banding or create blocks. Very short or already efficient videos may become larger after re-encoding. Re-encoding a lossy file cannot recover detail already removed.

Choose a sensible test

Start with a short representative segment. Compare motion, text and dark scenes, not only file size. Reducing 4K to 1080p or lowering frame rate can help on limited devices, but those transformations are not lossless.

Browser resource limits

Large source files may expand dramatically during decoding. Keep the tab open, use supported short clips, and consider lower-resolution input if the browser reports memory pressure. This site runs standard conversion in your browser and does not silently send larger files to a server.

Method review: 18 October 2026. Examples are educational, not device compatibility guarantees. See supported formats and limits and privacy practices.