Itunes says iphone is over capacity but there is nothing on it?

I just got a new iphone 4s and wasn't able to get my old iphone data onto it so it's completely empty. But when I try to sync it to itunes it says it's over capacity. How do I fix this?

The amount of data that you are trying to put on your iphone may be more that your iphone is able to hold.

Quick question. How much space does your old and new iPhone have?

Check in iTunes capacity, You can see what holding more space in your iPhone memory, If it is Apps then delete the apps, if it is music, Photos, movies etc then find the folder (Open iTunes. Choose Edit > Preferences. Click the Advanced tab in the Preferences window.) You can find where is your iTune folder is located and in iTunes media folder you can find all the folders (music, movie, apps etc) and delete whatever you want too and then sync your iPhone again.
And also
In Settings -> Safari -> Clear History, Clear Cookies and Data. That would help you to get some space.

Good luck.