"Which snowboard size shall I get? Should it hit my chin?" Maybe, but it's not all about your height (that dictates where the center of mass is), your weight also matters (it putt's more or less pressure on the snowboard), as do your gender (height/weight ratios and COM differs between genders), level of riding and riding style. All the boards have a size chart based on height, weight or both and you should always check it, no one knows a board better than who made it. For any beginner that will do it, for any intermediate or more experienced rider who wants to push their riding it won´t be enough.
Unless we are talking about a powder board that needs more surface to float and sizes may vary, a standard snowboard size is pretty predictable. The number you'll take from here will save you time by alowing you to look for boards within a certain size range, will help you to go straight to the point and to avoid a not-so-good-for-you-boardsize while buying your new snowboard.
Choose your snowboard size with the size table
Follow this three easy steps:
1 - Know your height and weight and find yourself in the Snowboard Size Chart (bellow).
2 - Now that you know the standard snowboard size for your weight X height, mix it with your riding level and riding style.