Audio File Size Calculator
Why an Album Fits Differently on Different Formats
The same three-minute song can be a 30 MB WAV file or a 3 MB MP3, and the difference comes down entirely to how the format stores data. Uncompressed formats store every sample directly, so their size is fixed by sample rate, bit depth, and channel count. Compressed formats instead target a bitrate, discarding or re-encoding data to hit it, which makes their file size depend on bitrate and duration alone.
The Formulas
Uncompressed (PCM):
Size (bytes) = Sample Rate × (Bit Depth / 8) × Channels × Duration (s)
Compressed (bitrate-based, e.g. MP3, AAC):
Size (bytes) = (Bitrate (kbps) × 1000 / 8) × Duration (s)
Size (bytes) = Sample Rate × (Bit Depth / 8) × Channels × Duration (s)
Compressed (bitrate-based, e.g. MP3, AAC):
Size (bytes) = (Bitrate (kbps) × 1000 / 8) × Duration (s)
A Three-Minute Track Across Formats
| Format | Detail | File size |
|---|---|---|
| Uncompressed WAV | 44,100 Hz, 16-bit, stereo | 30.28 MB |
| MP3 | 320 kbps | 6.87 MB |
| MP3 | 128 kbps | 2.75 MB |
Compressed-format sizes here assume a constant bitrate; variable bitrate (VBR) encoding produces file sizes that vary with audio complexity rather than a single fixed rate.
Where This Gets Used
- Storage and download planning — estimating how many tracks fit on a device, or how long a download or upload will take at a given connection speed.
- Podcast and audiobook hosting — choosing a bitrate that balances audio quality against hosting storage and bandwidth costs.
- Archival decisions — deciding whether to keep uncompressed masters or convert to a lossy format for everyday listening copies.
How to Use This Calculator
- Choose Uncompressed or Compressed mode.
- Enter the audio duration in minutes.
- For uncompressed audio, enter sample rate, bit depth, and channel count. For compressed audio, enter the bitrate in kbps.
- Select Calculate to see the estimated file size in MB.
Related Calculations
Check the underlying bitrate for uncompressed formats with the Audio Bitrate Calculator, or verify a matching signal level with the Decibel Calculator.