Just a thought, does percentage of body weight really indicate proper load limit? Maybe there are better methods by which to determine such a thing?
Isn't the 25% B.S. just like that body weight/height chart we all saw in high school gym class (which by the way, that chart was developed more than 100 years ago when we knew practically nothing about body fat percent)--(plus, the chart does not take into fact the aspect of different body types)?
Why not take into account a persons muscle mass/strength or body fat percentage? Why not look at the weight that a person is used to carrying or even taking into account how they carry it? Do they carry it in a big loose sack or in a well organized, compact, multi-compartment, well supported, super-duper-manly-mega pack?
Also, how many calories do they burn/consume(aka-available energy)and do they stay well hydrated? I am sure you all can think of many other possible cryteria. Just my opinion. What does anyone/everyone else think!!!!!!! Is there a smarter way or are we all just to conventional, ha ha ha ha ha conventional ha ha he he he us he he ha he haha!!!!!!

i think it's an easy, quick way to come up with some quantifiable limit. i agree with you that it won't hold up under scrutiny, but but it's good to have some sort of standard floating around out there. no matter how muscular you are, your cartilage & bones can only take so much pounding.

I think 25% is a good figure for the average young person up to the age of about 15 or 16. Over that I think up to 33% is the supposed figure that is quoted commonly is South Australia, and probably isnt too far from the truth for the average fit person.

With proper training you can certainly go higher. Ive been training lately with packs up to 59.1kg. I weigh in at 73.5-75kg, depending on what Ive eaten, drunken, when I last went to the toilet, etc. So that means 78.8 to 80.4% of my body mass. A fair bit more than both those figures above. And I am by no means an elite athlete. I am sure if you got a proffesional mountaineer or special forces soldier they would scoff at the % I am doing and run away from me up a hill with it on.

I think the important thing is to limit pack weights as much as possible, especially with young, developing bodies who haven't really seen any muscular and skeletal stresses of that sort before. I think the 60lb figure that keeps floating around for NOLs packs is definitely way too much. I remember at 16 trying going for week long bushwalks with 22kg (lots of water) thinking "Oh my god, my body is going to break". Then when we loaded up with 5L more water I almost broke down and cried. And while I was pretty skinny, I was by no means unfit for my age. A couple of years on and I had heard about trips to South West Tasmania which required packs of 35kg, due to the harsh conditions gear, 17 days food, lilos for river rafting, etc. When I tried carrying that I thought it impossible. Now I dont even notice 35kg. Its certainly all relative to the individual.

First off, I agree with Colleen that we need at least some kind of standard by which to judge. However, your comment on cartilage and bones is from my veiw point only half correct.
It must be taken into account that just as muscle can be made to grow, so to can bone be made more thick/dense and cartilage made more thick and elastic. For example, a runners leg bones are usually denser than those of a mountain biker. The bones of a body builder are both thicker and denser to support the extra muscle mass. A shaolin monk can kick through concrete with his shins(something which would leave the rest of us crying and screaming in agony).
(Sidepoint-I am not joking about the monk, I have studied martial arts for years and was once fortunate enough to witness a demonstration).
The truth is that this strength of muscle/bone/cartilage/etc.. can be had by almost anyone. As such, bones and cartilage have very little inherent limit on what they can or can not take. It will vary widely from one person or lifestyle choice to another.
Also, a common point that I always here is the factor of age. Again, this is an almost pointless factor in the sense that it to will vary widely from person to person. Sometimes the 50 year old man kicks the 20 year old kids but, ha ha he he!!!
I think that any method applied over the vast majority of people will prove futile. I beleive that body weight must be considered exclusively on and individual basis. It would be nice if we could standardize things, but in my opinion it simply is not possible. Far too much variety.

In a similar thread somewhere, I saw someone state that the % should be based on your IDEAL weight, not your current weight. This would take into account body fat. Now, what percentage to use is still up for discussion (and in the end, I don't think there is any one answer) but thinking of it as pack+Fat weight is more likely to be accurate across body types.

jonathan, i concede that bones & bone strength vary widely. but we don't toss around terms like "runner's knees" for no reason. over the long term, heavy use of particular joints can cause long-term or permanent damage. and i suspect that the Shaolin monk has also learned a thing or two about functioning through pain - or through repeated abuse of his shins has managed to kill off his nerves. ;)


in short, everything is more complicated than we want to believe it is. so that's why "rules" like "25% of body weight" get circulated so much. it doesn't require us to think much beyond that simple calculation. and yes, i include myself among the mentally lazy.

I don't think this number takes into account the overweight or obese. And by the way, 196 million Americans are overweight, obese, or morbidly obese.

As an extreme example, a 500lb man cannot carry a 125lb pack.

I'm 6'0 with a medium build, which means that my maximum healthy weight is 180 lbs. A 45lb pack seems to me to be a max. safe carry at that height and weight.

But if I weighed 220, could I then carry 55 pounds safely? Carrying more fat does not mean that I can then carry more backpack. In the first example, the total load on my skeleton is 225lbs. In the second, the total load would be 265lbs! Those two loads are not equally safe or equally healthy.

I would argue that this oft-quoted 25% number is a *general guideline* for people who are within their medically healthy weight range. If you are above your own maximum healthy weight, (and statistically speaking you probably are,) I think your maximum safe carry goes *down* rather than *up*.

The simplest method is to convert your bodyweight to the ever popular English measurement of stones.
Now after much careful consideration limit your pack weight to one stone per third of a fortnight.
Alternatively carry what you have to but fill your companions packs with stones, for some reason this makes carrying your pack easier.

I am big. At 6'2" I use the BMI healthy weight based on height when figuring it out for the boys and myself. I figure the extra pounds I carry are already making my trip harder on the joints. Use common sense. If you are under the 'suggested weight' use your own weight. Otherwise 25% is still too high unless you are going out unsupported for a week or more... Then maybe.

I have my base weight down to 18 pounds solo (3 season). I expect to lighten that by 6 pounds by the time I am done making the tarp/tent and bag this summer.

Good luck, have fun and stay light!