Reducing Size of Output File

I am converting an MP3 into a 21 second ringtone. The usual size of the output file is about 350Kb. My phone can only use files that are no larger than 300Kb. How can I reduce the size of the file to accommodate this requirement? Thanks.

Various options:
Make the file shorter,
use a higher compression ratio,
If the file is stereo, make it mono,
Reduce the bit-depth.

Thanks for the tips.
I really want to try and keep the length of the mp3 at 21 seconds.
Splitting the tracks and making it mono didn’t effect much.
Dynamic Range Compressor didn’t make a difference in size
Using Set Rate only made the sound either slow down or speed up.

I’m I using the right tools that you recommended?

Which version of Audacity are you using? (Look in the Help menu > About Audacity)


The tools are somewhat limited in Audacity 1.2.x, but you can still increase the data compression (this is not the same as the “compression effect” - that’s "dynamic compression).

Go to “Edit menu > Preferences > File Formats”
Change the MP3 Export “Bit Rate” to a smaller number.

The smaller the bit-rate, the smaller the file will be, but the worse the sound quality.
A mono file will give better sound quality than a stereo file at the same bit rate, so for small file size make the track mono.

BAM! That did the trick. Thanks for the help. btw, do you think it makes any difference if I switch to mono first then save at lower bit rate, or should I save at lower bit rate then reopen and switch to mono?

Encoding to MP3 should be the last step in any audio project. Encoding to MP3 always looses some sound quality and this bad effect adds up each time that you encode, so do all of the edits on the original file (including making it mono), then Export as MP3 as the last step.