What size snowboard should i get for park?

So this season i want to get a good park board. I want to get the endeavor color series board but i have a problem. I need to know what size board i need Im 5 10" and 160. I have done the formula that is like size x 2.54 x 1.84 or something and i got a 156 It doesnt make sense. an other thing is i got ride delta MVMNT bindings in XL because it is 11-13 size boot and i want to use those bindings on my board i want to get either a 154 or a 151 i need help for which size i need