Why does the file size become so large?

[hiroking]

I have a MP3 format sound file, whose size is about 400KB. Since I wanted to add some effect on it, I edited the sound file at Audacidy, and exported it as a MP3 format sound file. But the file size became so huge, over 3MB!

Then, I opened the original 400kb MP3 format sound file again and without adding any effect, exported it as a MP3 format sound file. Again ,the file size became very large, this time, 1 MB!

Is there any way to reduce the file size? I want to use the sound file online, so the size should be smaller than 1MB.
And why does the file size become large withount adding any effect?

Thank you very much for your help!

[steve]

You are probably exporting as WAV rather than as MP3.
You must have LAME installed and set up in order to export as MP3:
http://audacityteam.org/help/faq?s=inst ... m=lame-mp3

[Locopomo]

..... or you are exporting as MP3, but the default bitrate setting in Audacity is higher than that of the imported file. Audacity isn't exporting the same MP3, it decompresses the file in order to work with it and then creates a new MP3 when exporting, hence the potential for a different filesize.

[steve]

That could explain the increase from 400 KB to 1 MB, but the first case was 400 KB to over 3MB, which sounds more like the difference between an MP3 and a WAV (approx 8:1)