why is when i covert mp3 to audio...?

Question

the amount of size in a disk is still like uncompressed... mp3 is now a loss format... why?

Answer 1

Uncompressed format would be a WAV file. Mp3 is a compressed format and will be smaller than a WAV file. The size of the mp3 will be dependent on the bitrate. The higher the bitrate, the larger the file. Typically a 128kbps song would be around 3MB. A 160kbps would be around 5MB. 192kbps starts approaching 8MB.

If your question is why is your mp3 the same size as your uncompressed, I would say to lower your bitrate. If I didn't understand you correctly, please rephrase. Your question is a bit vague and confusing.