How much space does my music take up?

I have 728 songs that take up 3.17 GB on iTunes. Is that normal? I download most of my music, would that cause the songs to take up more space?

I have an 8GB iphone 3GS, and with about 800 songs on there it says my music takes up most of the space. (3.1 GB)

all together, with all my apps and music and photos, it says I use about 5.3 GB. But that I only have 948 MB available?

3.17 gb for 728 songs means you have around 3 to 4 mb per song which is normal. Generally, a 3 minute mp3 song file takes up to 3 to 4 mb size minimum, so it is normal in your case to have this much space filled with songs. The quality of the song also decides space. A good quality file takes more space than a poor quality one. Normally there's also metadata in your phone, which takes up space too.Eg. The properties meta data as well as an image thumbnail file for each of your song. That is where there's so little space left in your iphone.

It depends on the bit rate of the songs. Normally the size of a song will be around 5 MB.So, as per that calculation the size of that songs is normal.

You have an iPhone 3GS 8gb, it does not mean that you will get full 8gb storage on it. Some of the space is taken up by iOS to save its files and log data. It can use upto 2gb or even more space on iPhone.
And an average 3 Min song takes upto 3-4 MB of space once you have synced it with iTunes, itunes coverts the song into samllest as possible and maintaining the quality. You 800 songs so it is fine use about 3GB of space on the card