How this calculation works
Bitrate measures bits per second, while file sizes are commonly measured in bytes. Add compatible audio and video rates, multiply by duration, and divide by eight to convert bits to bytes.
Bytes = (video Mbps + audio kbps ÷ 1,000) × 1,000,000 ÷ 8 × duration secondsA worked example
8 Mbps video plus 128 kbps audio for 10 minutes gives an estimated 609.6 MB payload.
Good to know
Uses an average constant rate. Container metadata, variable-rate changes and additional streams are excluded; it does not inspect or compress a file.
Eight bits make a byte, and prefixes add another distinction
A bitrate of 8 megabits per second corresponds to about one megabyte per second before additional streams and overhead. Forgetting the division by eight makes a size estimate eight times too large.
The tool also shows MB and MiB separately. Decimal MB use 1,000,000 bytes; binary MiB use 1,048,576. Two applications can show different numerical sizes for the same bytes if they use different units.
Resolution alone does not determine file size
A video’s dimensions and frame rate influence encoding decisions, but they do not uniquely specify the average bitrate. Two videos with the same resolution can have quite different compressed sizes because their content and encoding settings differ.
Use an actual or assumed average video bitrate and include the audio stream in its separately labeled kbps field. Variable-rate changes, metadata, subtitles and container overhead can make an exported file differ from this payload estimate.
A few questions, answered
Does this compress a file?
No. It estimates a size from your bitrate and duration inputs without uploading a file.
Should audio bitrate be entered in Mbps?
The audio field uses kbps. The tool converts it to the same scale as the video rate before adding them.