The Burton Elite Full-Zip Hoodie is the simple jacket solution you're looking for, because there's no reason to perform calculus when elementary math will do the trick. A drawcord hood provides coverage to keep cold air away from your neck and head, and patch-on hand-warmer pockets shield your hands from windy weather.
Regular fit is just right: Not too tight or too baggy
70% organic cotton / 30% polyester blend 300g brushed-back fleece
Jersey-lined hood with drawcord
Ribbed cuffs and hem
Patch-on hand-warmer pockets