Audio File Size Calculator

How to use

1. 1Pick a mode: Size from bitrate, Bitrate for size, Duration that fits, or Uncompressed WAV for raw PCM.
2. 2Set the duration with the Hours, Minutes, and Seconds fields, or load a preset like 3 min song, 45 min podcast, or 8 hr audiobook.
3. 3Choose a codec preset (Opus voice, MP3 podcast, MP3 320, AAC 256, FLAC, and similar) or switch to Custom and type your own Kbps value.
4. 4For WAV mode, pick a sample rate, a bit depth, and a channel count; the effective PCM bitrate is computed for you.
5. 5Read the file size, required bitrate, or duration result and use the inline Copy buttons or Copy summary to grab the figure.

About this tool

Audio File Size Calculator solves the standard relationship between bitrate, duration, and on-disk file size for any audio format. The math is the same identity every encoder uses: file size in bits equals bitrate in bits per second times duration in seconds, and file size in bytes equals that figure divided by eight. Pick a mode that matches the question you are actually asking. Size from bitrate takes a codec preset (Opus voice at 32 Kbps, MP3 voice at 64 Kbps, MP3 podcast at 96 Kbps, MP3 music at 128 or 192 or 320 Kbps, AAC at 160 or 256 Kbps, an approximate FLAC at 900 Kbps) or any custom Kbps value and a duration, then returns the resulting file size plus a per-minute approximation that doubles as a quick mental rule of thumb. Bitrate for size reverses the equation: type a target file size (KB, MB, or GB, in decimal SI bytes the way macOS and most browsers display them) and a duration, and the tool returns the exact bitrate required plus the closest standard codec preset and a one-line quality hint, so you can tell at a glance whether a 200 MB upload limit lines up with 96 Kbps voice or 192 Kbps music. Duration that fits answers the inverse question for a fixed bitrate and a fixed file size: how many minutes of audio fit. The Uncompressed WAV mode handles raw PCM specifically, using the linear formula sample rate (Hz) times bit depth (bits per sample) times channels (mono, stereo, 5.1, 7.1). Pick CD-quality 44.1 kHz at 16-bit stereo and you get the classic 1.4112 Mbps Red Book bitrate; pick 48 kHz at 24-bit stereo and you get the standard digital audio workstation master rate. Duration presets cover the cases podcasters and audiobook producers actually need: a 30 second clip, a 3 minute song, a 15 minute interview, a 45 minute or 60 minute podcast episode, a 2 hour or 8 hour audiobook. Each result panel includes inline Copy buttons and a Copy summary for sharing into a project plan, a contractor brief, or a spreadsheet. Useful for podcasters sizing an episode against a hosting bandwidth quota, audiobook producers projecting catalog storage, voice memo and lecture recorders planning offline capture buffers, music producers comparing lossy export presets against a streaming platform target, sound designers and game audio engineers estimating asset bundle weight, and anyone trying to decide whether to upload as MP3 or WAV. Container headers and ID3 tags are tiny relative to the audio payload and are not included; expect the real file on disk to be a few dozen to a few thousand bytes larger than the figure shown. Math runs entirely in your browser; bitrates, file sizes, and durations stay on your device.

Free to use. Works in your browser. No signup, no login.