Can someone explain this iStat nano memory reading?

[deosaa7]

http://i.imgur.com/f114b.png

I have 3 Safari windows, one of them with 8 tabs open, iCal, and Day One open. It says I have 0.98gb free and about 2gb used unless I'm missing something that adds to 3gb total - I'm probably missing something stupid but I have 4gb RAM so where is my other 1gb? Also isn't that a lot of memory for just those apps to be taking up?

AKD

 

[deosaa7]

UPDATE:

Running skype video chat, 2 Safari Windows with 5 tabs, Day One, and iCal and I have 800 free megabytes?! wtf

 

[gr8tfly]

You actually have almost 2GB available as "free".

See the section on "Inactive Memory": Mac OS X: Reading system memory usage in Activity Monitor

 

[deosaa7]

I'm an idiot, thanks.