Audio Bitrate Time Size Calculator

Audio file size: bitrate times duration

For audio the math is short: size = bitrate · duration. Take a 60-minute MP3 at 320 kbps and you get (320 · 3600) / 8 ≈ 144 MB. The bitrates you'll run into most often are MP3 at 128, 192 or 320 kbps, AAC somewhere in the 96–256 kbps range for the same perceived quality, Opus at 64–96 kbps (which sounds great on voice), and lossless FLAC sitting near 1000 kbps for 16-bit/44.1 kHz stereo. Sample rate and channel count play a part too, since 48 kHz stereo costs more than 44.1 kHz mono, but with compressed formats the bitrate has already baked those choices in.

Applications: podcasts, streaming and archiving

Podcasters usually stick to 64–128 kbps for mono voice, bumping up to 192 kbps when an episode leans heavily on music, all to spare their listeners' data plans. Spotify Premium pushes up to 320 kbps OGG/AAC. When you're archiving a lecture or an interview, FLAC or 256 kbps AAC is the safe bet. Voice memos get by fine on Opus or low-bitrate AAC without losing a word.

FAQ

320 kbps MP3 versus 192 kbps AAC? To most ears the 192 kbps AAC holds up just as well, and often a touch better, because it's the newer and more efficient codec.

When is FLAC worth it? Reach for it when you're archiving, mastering, or running an audiophile rig. For everyday listening, 256 kbps AAC already sounds clean enough that most people can't tell.

Does stereo double the size? Not quite. Joint stereo encoders share data across the two channels, so at the same bitrate target a stereo file tends to run only 30–50% larger than mono.