This is put up using a single 10x10 tarp and my tarp weighs in at 2.75 lbs. I don't know the inside dimensions but I've 5' 8' and have plenty of room for myself and gear and long as my little 4 legged beast. You have to set it up with the back into the wind and preferably with the door facing as much away from the wind too. Set up properly this bugger is darn near water & wind proof. And if you practice it a few times you can have it up and running in 5 minutes.

You can gain a bit more inside room by attaching a line to the ridge and lifting it up. Added bonus, if it's windy it will cut down on the noise! This one is my ALL TIME FAVORITE! 

FYI here's a link to my favorite tarp. He doesn't have a lot of gear but what he does have is beyond TOP SHELF!!