For all of you people like me, who want more in a game (In this case, Skyrim), you have come to the right place. I've been wanting all three of the of the DLC's but I wanted to know how much space I would need in order to do that. (Xbox 360) It was hard to find the answers I wanted, but eventually I found them. Here they are.
Dragonborn DLC- 786.95 MB
Dawngaurd DLC- 583.12 MB
Hearthfire DLC - 75.8 MB
All of the DLC's take up about 1.41 GB total. (I did the math for the total space needed for all three DLC's)