Audio Size Calculator
How big is an hour of audio? Bitrate × duration, every format at once.
About this calculator
Type a duration, read the whole table: MP3/AAC at every common bitrate, uncompressed WAV in stereo and speech formats, and a typical FLAC figure. The compressed rows are exact arithmetic; the estimates say they're estimates.
The arithmetic, and what the bitrates mean
Compressed audio is beautifully predictable: bitrate × duration ÷ 8 = size, exactly — a bitrate is bits per SECOND, so a 45-minute podcast at 128 kbps is 43.2 MB regardless of what's in it. That predictability is the planning tool: podcast hosting quotas, audiobook libraries, how many hours fit a phone or an MP3 player. The bitrate ladder in listening terms: 64 kbps is fine for mono voice (audiobook standard), 128 is acceptable music (the historical MP3 default), 192 is where most listeners stop hearing differences in blind tests, 256–320 is enthusiast headroom. Uncompressed WAV follows its own formula — sample rate × channels × bit depth — landing at ~10 MB per stereo minute (lower rates shrink it proportionally). FLAC is the honest asterisk: lossless compression depends on content — silence squeezes to almost nothing, dense cymbals barely shrink — so its row is a typical 60%, labelled as such. Turn sizes into transfer times with the download calculator, and count real bytes after the fact with your file manager, which never lies.
Frequently asked questions
How big is one hour of audio?
At 128 kbps MP3: 57.6 MB, exactly (128,000 bits × 3600 s ÷ 8). As stereo CD-quality WAV: about 605 MB. As 16 kHz mono speech WAV: 110 MB. The table computes all of them live.
Is the calculation exact?
For constant-bitrate compressed audio, yes — bitrate × seconds ÷ 8, plus a sliver of container overhead. VBR files and FLAC vary with content, and their rows say 'typical' honestly.
What bitrate should my podcast use?
64–96 kbps mono for pure speech, 128 stereo if music matters. Above 192, blind tests say almost nobody hears the difference — bytes spent on reassurance.
Why is WAV so much bigger?
No compression: 44,100 samples × 2 channels × 2 bytes each, every second — ~10 MB a minute. That's the price of the format everything can open.