How much should my pack weigh for backcountry hiking?
Each person is unique and should spend time discovering for themselves their optimum pack weight(s). For instance, my 9.5kg 7-day pack (and 6.16kg , 3-day pack) are optimum for me. I invested the time to discover what felt best.
I am 6'1 tall and weigh 85kg I do not smoke (anything) nor drink alcohol. I am not overweight and stay in good physical condition. I work out daily & carry a pack several times a week as part of the workout. I do most all of my packing in the hills and mountains where significant elevation gains are routine and weather conditions run the gamut.
One of the factors that I considered when pursuing the optimum pack weight was % of pack weight to body weight. My 7-day pack is 1/6 (16.4%) of my body weight. That was my goal for a 7-day pack - 1/6 bodyweight.
Over the years, I've heard that 1/4 of a person's body weight is an optimum pack weight and even 1/3 is okay, if you're in good shape! In recent years, I've been aiming at 1/5 to 1/7 of my body weight. Currently, for 3-season mountain travel, I'm very happy in the 1/6 range. In the Winter, I add more food, more clothes, a beefier sleeping bag, extra sleeping mat, more fuel, heavier stove, heavier boots, and so on. In Winter, my pack weight is more in the range of 1/5 to 1/4 of body weight.
... but, actually, pack weight is relative! Depending on your weight, conditioning, terrain, etc., your optimum pack weight, at any given time, could be 1/4 or maybe even 1/6.
The main point is to figure out for yourself what is optimum - (and the pack weight to body weight ratio is just one factor to consider) .
The big take away 'ounces count'