Bitrate and Encoding Method
Thebitrateused for encoding a song has a large effect on file size.
CBR is universally accepted despite known limitations in acoustic quality.
Audio Format
Choosing an audio format for your particular portable is also an important factor to consider.

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AAC, for example, is regarded as being better than MP3.
It typically produces higher quality audio and is more efficient at compression.
This format could give you more songs per gigabyte than if you use MP3 alone.
This isn’t an exact science, but it’ll give you a good idea.
Take the length of the song in seconds.
Then, multiply it by the bitrate of file.
Now, take the result, and divide it by the result of 8 multiplied by 1024.
That will convert from kilobits(kb) to megabytes(MB).
Instead, take an estimate.
Assume that the average length of your songs is 3.5 minutes.
That’s pretty standard.
Now, apply the formula.
Remember to multiply 3.5 by 60 to get the number of seconds.
Does that seem about right for your library?
1024 / 3.28
There you have it!
you’ve got the option to fit roughly 312 songs on 1GB of storage.
Examples
Assume a smartphone with 4 GB of available data storage.
Other Considerations
The MP3 format supports tags and album art.