Video File Size Calculator

How it works

Add the average bitrates of the video stream and all audio streams, then multiply by duration to get the media’s bit count. Divide by eight to obtain bytes. This calculator accepts video in decimal megabits per second and audio in decimal kilobits per second. It reports both decimal MB/GB and binary MiB/GiB so the result can be compared with different storage displays.

A bitrate is an average over time. With constant bitrate encoding, the estimate is usually easier to make; variable bitrate content depends on motion, detail and encoder settings. Resolution and frame rate influence the bitrate an encoder may need, but they do not uniquely determine file size. A highly compressed 4K video can be smaller than a high-bitrate 1080p video of the same length.

Container metadata, subtitles, thumbnails and additional tracks can add bytes. Enter their allowance in the optional overhead field, or leave it at zero for a media-payload estimate. There is no universal overhead percentage, so the field is an explicit assumption rather than an automatic claim of accuracy. If an encoder reports an overall bitrate that already includes audio, do not add the same audio again. For a finished file, its actual byte count is more accurate than any estimate.

A worked example

Ten minutes at 8 Mbps video plus 192 kbps audio contains about 614.4 MB of media payload. With an assumed 2% additional overhead, the estimate becomes 626.688 MB.

Common questions