The Burton Elite Full-Zip Hoodie is the simple solution you're looking for, because there's no reason to perform calculus when elementary algebra 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
Cotton and recycled polyester blend 305g brushed-back fleece
Jersey-lined hood with drawcord
Ribbed cuffs and hem
Patch on hand-warmer pockets