How to use this calculator
Choose file size or video bitrate. Enter duration in seconds and the audio bitrate in Kbps; use zero for a silent video. File size uses decimal MB.
The math behind it
File size (MB) = (video Mbps + audio Kbps ÷ 1,000) × seconds ÷ 8 Video Mbps = file size (MB) × 8 ÷ seconds − audio Kbps ÷ 1,000
A worked example
60 seconds at 8 Mbps video plus 128 Kbps audio uses approximately 60.96 MB before container overhead.
Assumptions & precision
Average constant bitrate model. For variable bitrate, enter its average. Excludes container overhead, metadata, subtitles and extra tracks. Duration must be positive. A target too small to hold the audio alone is rejected. Zero video bitrate is permitted as a mathematical audio-only budget. Unrounded intermediate values; results display up to 6 decimal places. Magnitudes above 10¹⁵ are rejected.
A common question
Will an encoded file be exactly this size?
Usually not. Encoder variability and container overhead affect final size; leave headroom when meeting an upload limit.