Audio Length from Size
Estimate audio duration from file size and bitrate.
How long is that audio file?
Given a file size and a constant bitrate, playback length is simple arithmetic: length equals size in bits divided by bitrate. A 5 MB file at 128 kbps runs about 5.2 minutes, which is why podcasts quote both numbers.
It is handy in reverse too: if a podcast host caps uploads at 200 MB, you can see roughly how many minutes that allows at your chosen bitrate before you record.
Why it is an estimate
Variable-bitrate files and container overhead shift the real duration slightly, so treat the answer as close rather than exact. Nothing you enter leaves your device.
Frequently Asked Questions
How does the audio length from size work?
Duration equals file size in bits divided by bitrate. A 50 MB audio file at 128 kbps lasts about 54.6 minutes.
When should I use this tool?
Use it to estimate podcast, audiobook, voice memo, and music file lengths from size and encoding rate.
What is the main limitation?
Variable bitrate files and metadata overhead make this an estimate.
Is this converter private?
Yes. It runs entirely in your browser, so your values are not uploaded or stored.
More free browser utilities for conversion, formatting, and technical cleanup.