It's thin, so easily fits into a pocket or travel belt. (charlieontravel.com)
It certainly does not fit into the pocket at all, and must be carried in a messenger bag. (goodereader.com)
Now, while it can't actually fit into your pockets, it CAN fit into your backpack or diaper bag thanks to it's tiny 35 cm x 30 cm x 18 cm! (simplyrealmoms.com)