How do I choose the right length for Nordic backcountry skis?

Nordic backcountry skis should generally be 10–20cm taller than your height, which is longer than alpine skis for the same rider. The extra length provides glide efficiency and proper kick-and-glide mechanics. Within that range, go longer if you are heavier, ski primarily on flat/rolling terrain, or prioritize touring efficiency. Go shorter if you are lighter, ski tighter terrain with more trees, or prioritize downhill maneuverability. The ski must be long enough that the camber supports your weight without fully collapsing—if the fishscales drag while you are gliding, the ski is too soft or too short for your weight.