Audio File Size Calculator
Estimate MP3/audio size from bitrate and duration, or calculate a safe bitrate for a target file size.
Estimate audio file size
Enter the total audio bitrate and duration. For ordinary constant-bitrate MP3, this gives a practical size estimate before encoding.
Find bitrate for a target size
Useful when an MP3 needs to stay below an email, messaging, upload, or storage limit.
Know the size before you encode.
How audio file size is estimated.
For constant or average bitrate audio, file size is mostly bitrate multiplied by duration. Container metadata can add a small amount of overhead.
What common MP3 bitrates mean for size.
These examples use decimal MB and exclude small metadata/container differences.
| Bitrate | 3 minutes | 5 minutes | 60 minutes |
|---|---|---|---|
| 64 kbps | 1.44 MB | 2.40 MB | 28.8 MB |
| 96 kbps | 2.16 MB | 3.60 MB | 43.2 MB |
| 128 kbps | 2.88 MB | 4.80 MB | 57.6 MB |
| 192 kbps | 4.32 MB | 7.20 MB | 86.4 MB |
| 320 kbps | 7.20 MB | 12.0 MB | 144 MB |
Turn the estimate into a real file.
Convert uncompressed audio to MP3, shorten the recording, or check its tempo before export.
Bitrate, MB, and real-world differences.
Why can the final MP3 differ from the estimate?
Metadata, container overhead, encoder behavior, and variable bitrate can make the final file slightly different. Use a safety margin when a hard size cap matters.
Is 128 kbps always good enough?
It depends on the source and use. Speech often works well at lower bitrates, while complex music can benefit from 192 kbps or higher.
What is the difference between MB and MiB?
MB uses 1,000,000 bytes. MiB uses 1,048,576 bytes. This calculator displays both in file-size mode.
Does the calculator upload anything?
No file is needed. Generic analytics records that the calculator was used, but not the numbers you entered or calculated.