Audio File Size & Bitrate
PCM size from sample rate, bit depth, channels and duration; compressed size from a bit rate; or the bit rate and duration a file size implies.
Bit rate, duration, bytes in decimal and binary units, MB per minute, how many fit in a GB and the batch total — with the header, VBR and tag caveats stated.
Example: 44.1 kHz, 16-bit stereo is 1,411.2 kbit/s: 3:30 of it is 37.04 MB (10.58 MB per minute). Twelve hour-long tracks at 128 kbit/s are 691.2 MB; a 4.2 MB file lasting 4:22 averaged 128.2 kbit/s.
Samples × bits,
or bit rate × time.
The two ways an audio file gets its size, and the caveats around headers, VBR and units.
PCM
An uncompressed recording stores every sample: bit rate = sample rate × bit depth × channels (44.1 kHz × 16 bit × 2 = 1,411.2 kbit/s), and size = bit rate × seconds ÷ 8. A WAV or AIFF adds a small header (44 bytes for a canonical WAV), so the file is marginally larger than the samples. Lossless codecs (FLAC, ALAC) shrink that by a ratio that depends on the material and is not predicted.
Compressed
For MP3, AAC, Opus and the like the size follows the encoder’s bit rate: size = kbit/s × seconds ÷ 8. That is exact for constant bit rate; VBR files vary around their nominal setting, and tags or cover art add bytes. The reverse modes divide a file size by its duration for the average bit rate, or by a bit rate for the duration.
Units
MB and GB are decimal (10⁶, 10⁹), which is how storage is sold and how most players report; MiB and GiB (2²⁰, 2³⁰) are what some operating systems show, and both are printed. kbit/s means 1000 bit/s. No codec presets are embedded — enter the rate your encoder uses. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- PCM bit rate = sample rate × bit depth × channels; size = bit rate × seconds ÷ 8; bit rate = size × 8 ÷ seconds; decimal MB (10⁶) and binary MiB (2²⁰) both shown — no codec presets embedded
Last reviewed 21 September 2026. How results are checked: How we verify.