What this calculator does
This tool estimates how large an audio file will be based on its length and its encoding bitrate, which is useful for planning storage space, upload times, or mobile data usage.
How the calculation works
File size is calculated as bitrate (in kilobits per second) multiplied by duration in seconds, then converted from bits to bytes by dividing by 8. Bitrate-based estimation works for common compressed formats like MP3, AAC, and Opus, where the bitrate is roughly constant throughout the file.
Uncompressed formats (like WAV) or variable-bitrate encoding will produce sizes that differ somewhat from this estimate, since their effective average bitrate can vary.
Last reviewed August 2026