Calculate audio file size, bit rate, or duration for audio recordings by choosing the result and entering the other two values with units like kbps, minutes, MiB, or GiB.
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Audio File Size Formula
The audio file size calculator uses bit rate, duration, and file size. The base calculation uses bit rate in bits per second, duration in seconds, and file size in bytes.
- File Size is the estimated audio payload. Results show decimal MB and GB alongside binary MiB; inputs also support bytes, KB, KiB, and GiB.
- Bit Rate is the amount of audio data used per second. The calculator can use bps, kbps, or Mbps.
- Duration is the length of the audio. The calculator can use seconds, minutes, or hours.
- 8 converts bits to bytes because 1 byte equals 8 bits.
If you enter bit rate and duration, the calculator finds the file size. If you enter file size and duration, it finds the required bit rate. If you enter file size and bit rate, it finds how long the audio can be.
Common Audio Bit Rates and Approximate File Sizes
These values use binary MiB and are approximate audio payload sizes. Actual file sizes can vary because of metadata, encoding settings, and whether the bit rate is constant or variable.
| Audio Type or Quality | Typical Bit Rate | Approx. Size for 1 Minute | Approx. Size for 1 Hour |
|---|---|---|---|
| Low quality voice | 64 kbps | 0.46 MiB | 27.47 MiB |
| Standard podcast or speech | 96 kbps | 0.69 MiB | 41.20 MiB |
| Common music streaming quality | 128 kbps | 0.92 MiB | 54.93 MiB |
| Higher quality MP3 | 320 kbps | 2.29 MiB | 137.33 MiB |
| Uncompressed CD-quality PCM | 1411.2 kbps | 10.09 MiB | 605.58 MiB |
Audio Unit Conversions Used
| Unit | Conversion |
|---|---|
| 1 kbps | 1,000 bits per second |
| 1 Mbps | 1,000,000 bits per second |
| 1 minute | 60 seconds |
| 1 hour | 3,600 seconds |
| 1 KiB | 1,024 bytes |
| 1 MiB | 1,048,576 bytes |
| 1 GiB | 1,073,741,824 bytes |
Example Calculations
Example 1: Find audio file size
You have a 128 kbps audio file that is 3 minutes long.
2,880,000 bytes is about 2.75 MiB.
Example 2: Find required bit rate
You want a 10 MiB audio file to last 5 minutes.
279,620.27 bps is about 279.62 kbps.
FAQ
Why does the formula divide by 8?
Bit rate is measured in bits per second, but file size is usually measured in bytes, KiB, MiB, or GiB. Since 1 byte equals 8 bits, the formula divides by 8 when converting bit rate and time into file size.
Why is my real audio file size different from the calculated size?
The result is based on the audio data rate and duration. Real files may include headers, tags, album art, metadata, padding, or variable bit rate encoding. These can make the actual file slightly larger or smaller than the calculated value.
Does a higher bit rate always mean better audio?
For comparable encoding settings, a higher bit rate usually allows more audio detail and creates a larger file. Bit rate alone does not establish quality across different codecs. The difference may not be noticeable if the source audio is low quality, the playback device is limited, or the listener is using basic speakers or earbuds.
