Audio Bitrate Calculator
Switch between estimating a track's file size from its bitrate and duration, and working out the bitrate needed to fit a track into a target file size. Enter the values you know and watch the result update instantly.
How it works
File size, in bits, is simply bitrate × duration: at a constant bitrate, every second of audio takes up the same number of bits. In megabytes, that works out to bitrate (kbps) × duration (seconds) ÷ 8 ÷ 1024. This calculator runs that relationship in either direction — from bitrate and duration to file size, or from a target file size and duration back to the bitrate you'd need.
Tip
This assumes a constant bitrate (CBR). Variable bitrate (VBR) encoders raise or lower the bitrate throughout a track depending on how complex the audio is at each moment, so a VBR file's actual size will only roughly match this estimate.