Audio file size calculator
Enter any two of file size, bitrate and duration to get the third. Pick a common MP3 bitrate from 64 to 320 kbps, or work out uncompressed WAV from its sample rate, bit depth and channels.
Sizes are shown in both MB and MiB, because operating systems and apps do not agree on what a megabyte is. The calculation runs in your browser.
Audio type
Work out the
MB (1,000,000 bytes)
3.36 MB
Decimal, as macOS shows sizes
MiB (1,048,576 bytes)
3.2 MiB
Binary, as Windows shows sizes (labelled MB)
Bytes
3,360,000
At 128 kbps
Size per minute and per hour
| Bitrate | 1 minute | 1 hour |
|---|---|---|
| 64 kbps | 0.48 MB · 0.458 MiB | 28.8 MB · 27.47 MiB |
| 96 kbps | 0.72 MB · 0.687 MiB | 43.2 MB · 41.2 MiB |
| 128 kbps | 0.96 MB · 0.916 MiB | 57.6 MB · 54.93 MiB |
| 192 kbps | 1.44 MB · 1.37 MiB | 86.4 MB · 82.4 MiB |
| 320 kbps | 2.4 MB · 2.29 MiB | 144 MB · 137.33 MiB |
| WAV, 44.1 kHz, 16-bit, stereo | 10.58 MB · 10.09 MiB | 635.04 MB · 605.62 MiB |
| WAV, 48 kHz, 24-bit, stereo | 17.28 MB · 16.48 MiB | 1,037 MB · 988.77 MiB |
Need the audio itself? Type a script in the editor and download it as a voice-over. The free plan includes 25,000 characters a month, no card needed.
How to calculate an audio file's size
- 1
Choose what to work out: the file size, the bitrate or the duration.
- 2
Pick a bitrate such as 128 kbps, or switch to WAV and set the sample rate, bit depth and channels.
- 3
Enter the other value, like a duration of 3 minutes 30 seconds or a size of 5 MB.
- 4
Read the size in MB and MiB, or the bitrate or running time it works out.
Good to know
The formula
File size in bytes is the bitrate in bits per second times the duration in seconds, divided by 8. At 128 kbps that is 128,000 × 60 ÷ 8 = 960,000 bytes, or 0.96 MB, a minute.
MB or MiB?
A megabyte (MB) is 1,000,000 bytes and a mebibyte (MiB) is 1,048,576. Windows shows sizes in MiB but labels them MB, while macOS uses MB, so the same file looks about 5% smaller on Windows.
WAV is uncompressed
CD-quality WAV (44,100 Hz, 16-bit, stereo) runs at 1,411.2 kbps, about 10.58 MB a minute: more than ten times a 128 kbps MP3.
Real files differ a little
Tags, cover art and the file header add to every file, and a variable-bitrate (VBR) file only averages out to its bitrate, so treat the result as a close estimate.
Questions, answered
How big is a 1-minute MP3?
About 0.96 MB at 128 kbps, 1.44 MB at 192 kbps and 2.4 MB at 320 kbps. At 64 kbps, common for spoken-word audio, it is about 0.48 MB.
How do I calculate audio file size?
Multiply the bitrate in bits per second by the length in seconds and divide by 8 to get bytes. A 4-minute track at 192 kbps is 192,000 × 240 ÷ 8 = 5,760,000 bytes, about 5.76 MB.
How big is a WAV file per minute?
About 10.58 MB at 44,100 Hz, 16-bit stereo, and about 17.28 MB at 48,000 Hz, 24-bit stereo. Mono is half that.
Why does my computer show a different size?
Some systems count a megabyte as 1,048,576 bytes (a MiB) but still write MB, so the number looks about 5% smaller. Tags and cover art also add to the file, and variable-bitrate files only average out to their bitrate.
What bitrate are ToneCraft voice-overs?
MP3 voice-overs from the ToneCraft editor are encoded at 192 kbps, so each minute is about 1.44 MB. Enter any length above to see the size of a longer one.
Does it work for AAC, Opus or FLAC?
For AAC, Opus and other formats with a set bitrate, yes: enter the bitrate and the length. FLAC and other lossless formats compress each recording by a different amount, so their size cannot be worked out from settings alone.