Formula and units
Compressed bytes = duration in seconds × bitrate in kbps × 1,000 ÷ 8. The calculator uses decimal kbit/s, shows storage in decimal MB/GB, and also shows binary MiB/GiB so the same byte count is not mistaken for two different files.
Audio file size calculator
Estimate MP3, AAC, Opus, or other constant/average-bitrate audio sizes from duration and bitrate. Compare six common rates and raw PCM/WAV sample data instantly.
Audio duration
Estimated compressed size
2.88 MBBinary display2.75 MiB
Exact calculated bytes2,880,000
Bitrate size comparison
The same duration at each constant bitrate. This lets you compare storage before encoding.
| Bitrate | Decimal size | MiB/GiB |
|---|---|---|
| 64 kbps | 1.44 MB | 1.37 MiB |
| 96 kbps | 2.16 MB | 2.06 MiB |
| 128 kbps | 2.88 MB | 2.75 MiB |
| 192 kbps | 4.32 MB | 4.12 MiB |
| 256 kbps | 5.76 MB | 5.49 MiB |
| 320 kbps | 7.20 MB | 6.87 MiB |
PCM/WAV reference
For comparison, raw PCM sample data uses sample rate × bit depth × channels × duration. A WAV container normally adds a small header.
44.1 kHz · 16-bit · stereo31.75 MB30.28 MiB
48 kHz · 24-bit · stereo51.84 MB49.44 MiB
What the estimate includes
- It models constant bitrate (CBR) or a known average bitrate. Variable-bitrate files can differ because their actual average rate depends on the encoded audio.
- Container headers, tags, artwork, encoder padding, and other metadata are excluded, so an exported file may be slightly larger.
- Bitrate describes data per second; it does not prove perceptual quality. Codec, source, and encoder settings also matter.
- For lossless formats such as FLAC, size cannot be predicted exactly from duration alone because compression depends on the signal.
Useful for storage and export planning
- Estimate podcast episode storage before recording or publishing.
- Compare MP3 bitrate choices before using the converter.
- Plan a music, audiobook, lecture, or voice-note archive.
- Check whether a batch is likely to fit a storage or upload allowance.
The calculation stays in this tab
This page does not request an audio file. The values you type are multiplied locally in your browser; no media is uploaded for this estimate. The site may still load normal page resources and consented analytics.
Turn the estimate into an MP3
When you have chosen a rate, use the browser-based bitrate converter to encode a real MP3 and compare the final byte size with this planning estimate.
Open the MP3 bitrate converter