What Size snowboarding boots should I buy!?!?

I want to buy a snowboard for my boyfriend for Christmas. Hes 5 foot 11 inches. Hes a really Skinny guy. I figured he needed around a 156 cm length board. He also has really big feet he wears 11.5 in a reg shoe size. So I also figured he needed a wide board. My question is do snowboard boots run the same size as regular shoes. Should I get him 11.5 in snowboard boots or do they run a little big or small?