Default why is it 11.44GB total space?

I'm S-OFF and rooted and running CM 11. Why does my phone only hold 11.44 GB yet the DNA is suppose to hold 16? I added up all the app data, photos and videos, misc's, downloads, audio, cached data, and free space through the storage feature in CyanogenMod and it totalled to be around 11GB. Why is this?

Here is a screen shot