How to reduce a video file size

Codecs, containers and where the bytes are

A file format such as MP4 is a container: a box that holds a video track, an audio track and timing information. The codec is the method used to compress what goes inside, typically H.264 video and AAC audio in an MP4. Two files in the same container can differ enormously in size depending on the codec and bitrate.

Compression is almost always lossy: detail is discarded so the data fits in fewer bytes, because lossless formats retain the original information and may not reduce the file enough for a strict sharing limit.

Two ways to shrink in Clipy

The general compressor re-encodes your video at a lower bitrate for a smaller file. The fit-to-size tool works from the other direction: you set a target size and it calculates the bitrate that fits. Trimming to the part that matters helps both, and cuts video seconds are seconds not encoded at all.

1. Add your video, up to 250 MB and 10 minutes.
2. Trim the clip first if only part of it matters.
3. Choose the general compressor for a lighter file, or fit-to-size for an exact limit.
4. Check the result, especially motion and on-screen text.
5. Keep the original until you have checked the export.

Troubleshooting

If the result looks soft, a lower resolution or a shorter clip frees bitrate for quality. If the file barely shrank, the source was already efficient and needs a lower bitrate. If playback fails on another device, convert to MP4 with H.264 video and AAC audio. Trimming is exact but slower with re-encoding, or quick when the cut snaps to the nearest keyframe.

Common questions