Apt-get displays the total size of all downloads required for an upgrade or install. I was wondering if we could get the size of each package that is going to be downloaded as well? An aptitude solution would be useful as well.
You can use the aptitude curses interface for this. Start aptitude without any parameters
Then find the package(s) you want to install (you can for example press 'l' and enter the package name to find it). Press '+' to mark it for installation (repeat for other packages). Press 'g' to apply changes. Here you will see next to each package the size change.
If you want to modify what you see, you can go to Options and modify 'The display format for package views'. E.g you could include %D to show the package size.
Look here for a reference of available options Customizing the Package List