file sizes are wacky!

i have a Macbook running 10.5.8 with Audacity I downloaded two MP3 files, the first was 3.1 MB and the second was 1.6 MB and when I combined them in Audacity to make one file and exported it as an MP3 it is now 18.7 MB. What the heck happened??? Is there any way to get it down to 4 or 5 MB??? Or preferably, smaller?

Thanks. (I’m a relative newbie, so forgive a potentially dumb question if there’s a command somewhere to shrink file sizes).

Audacity doesn’t edit MP3. It pulls the music inside itself in a very high quality format, edits it, and then creates a whole new MP3 when it’s done. So the output MP3 can be whatever size you want by managing the bitrate with the options part of the export panel.


The honky, gargling and bubbling compression damage goes up each time you make another MP3. So the music damage could be significant in your new show. No, Audacity doesn’t naturally want to make files the same size as the originals.

MP3Splt will do simple editing without the recompression and sound damage step. That may work for you.


Um, I think mp3split doesn’t join files. For that you want but that is command-line and has no Mac support unless you want to compile it.

I don’t know if Macsome or Audion join MP3 files losslessly - check them out here

I think possibly Audion does joins. If you try them, please let us know.


The larger file size is because you exported at a higher bit rate than the original files had. You can reduce the bit rate (and thus the file size) by clicking the “Options…” button when you export.

But as Koz says, any re-encoding of MP3 as another MP3 makes the quality even worse. The higher the bit rate you export at, the less the damage.