Companion blog: Adventures In Stoving

Sunday, May 31, 2015

Proportional Total Pack Weight

Let's talk about pack weight.  There are three types of weight that are most frequently talked about:  Base weight, consumables weight, and total pack weight.  You'll also hear about "skin out" weight which is the weight of everything but your birthday suit.  Skin out weight is a little harder to calculate and work with, particularly for those who like to "weigh in" at the trailhead, so I'm just going to focus on the more common ways to look at pack weight:  base weight, consumables weight, and total pack weight.  Here are my explanations:
  • Base Weight.  This is the weight of things that don't vary with the length of a trip.  For example, my sleeping bag weighs 1.3 lbs whether I take a 3 day trip or a 7 day trip.   
  • Consumables Weight.  Typically food, fuel, and water.   Taking the example of a 3 day vs. a 7 day trip, if I carry about 2 lbs of food per day, then for a 3 day trip, I'd carry 6 lbs of food whereas for a 7 day trip, I'd carry 14.
  • Total Pack Weight. Total pack weight is the sum of your base weight + your consumables weight and is sometimes referred to as just "pack weight."
Now, the tendency is for hikers to focus on their base weight.  Consumables weight is after all a function of how long a trip is rather than good gear planning.  I mean you have to eat, so long as you're not carrying excessive amounts of food per day, there's not much you can do to reduce weight (short of someone hiking in supplies to you or you hiking out for supplies).  If you carry X pounds of food per day and hike Y days, then your weight is X times Y, and you're pretty much stuck with it.  So base weight, which is not dictated by the length of the trip, makes a lot of sense to focus on.

But total pack weight still matters.  I mean there's an upper limit to what a given human being can carry.  Go past certain limits, and you get into the "suffering zone."  We're out there to enjoy this right?  I just gave up my vacation to go backpacking because it's going to be fun, remember?  If it's not fun, then just why am I doing it?
My camp at Iceberg Lake, July 2015.  Don't ruin a beautiful backpacking trip with a heavy pack!
Consider a recent desert trip I did.  I consumed 7 liters of water from the time I left one water source until I reached the next about 24 hours later.  A liter weighs 2.2 pounds, so 7 liters weighs 15.4 pounds.  So let's say I have a 15 lbs base weight, and I'm carrying 10 lbs of food (five days worth), and say 1/2 lbs of fuel.  I'm now at 41 lbs which is a fairly heavy backpack to be lugging over mountainous desert terrain.  And what if I had come to water after 48 hours instead of just 24?  Now we're talking about a 56+ lbs backpack.  And so on, and so on...  The point is that even if you have a low base weight, you can still wind up with a heavy pack, depending on the length of a trip and the availability of water.
Tunnel Spring on the Desert Divide in the San Jacinto Mountains.  It looks pretty gross, but we wouldn't see water again until the evening of the following day.  We tanked up and were grateful.
So you have to consider the overall weight of your pack.  I mean you have to be physically able to carry the dang thing, and oh yes, we'd like to be able to enjoy ourselves at the same time.

OK, great, but what's our framework for judging whether or not a particular pack weight is appropriate?  Good question.  I'd like to propose the following schema, a schema based on total pack weight as a proportion of one's body weight:
A chart showing pack weights as a proportion of one's body weight and the perceived weight category.
The idea here is that what a 200 lbs 6'0" tall person might call light is not the same as what a 150 lbs 5'6" person would call light.  The weight that it will be comfortable for a given person to carry varies in proportion to their body weight.

My experience is that most reasonably fit people who have a decent amount of hiking experience will find a total pack weight equal to 1/6th of their body weight as a "moderate" backpack.  In other words, most reasonably fit hikers can handle a pack that weighs about 1/6th of their own weight.  It won't be easy, people won't remark "oh, it's as light as a feather," but people can handle it and still have a reasonably enjoyable time.

Now, a lot of books will suggest 1/3rd of your body weight as an upper limit.  One-third?  Really?  I weigh 220 lbs.  1/3 of my body weight is about 73 pounds!  Like I'm really going to hike with 73 freaking pounds on my back!  Not happening.  Now, really fit, really strong people can do it I'm sure, and a lot of hard core mountaineers probably do it all the time, but for the average hiker that I've met, no, 1/3rd is completely unrealistic.  Take a look at the photo below.  That's what 1/3rd of one's body weight looks like.  Yes, it can be done, but isn't any fun, and in fact I've never been so exhausted in all my life as when I've had to carry not only a heavy pack but also my daughter.  Again, for most hikers, 1/6th of your body weight is a desireable pack weight to shoot for.  My recommendation is DON'T exceed 1/6th of your body weight unless you're an experienced backpacker who is getting out regularly and has worked up to carrying greater (proportionally) weights.
The author, carrying approximately 1/3rd of his body weight.  It can be done, but it isn't fun.
Now, is even lighter than 1/6th of one's own body weight more comfortable?  Of course.  I'm proposing 1/6th as a reasonably comfortable upper limit.  If you can figure out ways to carry even less, by all means you should do so (so long as you are still reasonably safe and comfortable).

Indeed, if you've read any of my recent posts, they're all about trying to go from carrying a pack that weighs about 1/6th of my body weight to one that weighs about 1/8th of my body weight.

Lastly, if you look at the chart, you'll see some categories like "Extremely heavy," "very heavy," "moderate," "light," etc.  Don't get too hung up on the exact category.  The idea is to suggest where along the continuum most people will perceive a particular pack weight at a given proportion of their body weight.  Obviously, proportions greater than 1/6th are some form of "heavy" whereas those that are less are some form of "light".

The idea here is not to set target categories but to stimulate thought. One should ask "What is my total pack weight going to be for the trip I'm planning?" and "is that weight a) realistic and b) reasonably comfortable?"

So, there you have it.  While base weight is something to pay attention to, one should also keep in mind one's total pack weight.  My recommendation is that total pack weight generally should be no more than 1/6th of one's body weight – at least until one has the experience to know otherwise.

I invite your reflections and comments, below.

HJ


12 comments:

  1. "Go past certain limits, and you get into the "suffering zone." Were out there to enjoy this right?"

    So very true!

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    1. Well, it's certainly my observation!

      HJ

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  2. What about 'bulk'? Especially if you're a shorter person then it isn't only pack weight which is an issue!

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    1. Yeah. Hmm. Good point. I'm not sure how to get a good metric on bulk; I mean it's not like you can plop it on a scale and say you've got 22.7 "bulks". But yeah, bulk is an issue. I recently bought a NeoAir pad for my daughter even though she sleeps fine on a cheap closed cell foam (CCF) pad. Why? Mainly because the NeoAir fits inside my backpack whereas the CCF hung outside and banged around. I want a streamlined, low bulk, symmetrical pack.

      HJ

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  3. What do you mean, "gave up my vacation to go backpacking"????? What else would you rather do? ;-)

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    1. Hey, just don't screw up my vacation, OK?

      HJ

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  4. I'm a human biomechanics researcher and I arrived at fairly similar numbers when accounting for physical fitness metrics and weather (I make fairly complex mathematical models for fun, I'll admit). For me personally, the model equates to 5-7% bodyweight for base weight, 3-5% for consumables (relative to temps and duration), and then a 3% base weight increase allowance for winter (I do a lot of winter packing in WY and MI).

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    1. Hi, Mitch,

      Sorry not to reply sooner. Been busy (and spending some time up in the Sierra). :)

      Very interesting. My recommendation to not exceed 1/6th of one's body weight for comfortable backpacking equates to about 17% Your max based on the above listed numbers would be about 15% (for winter) which is reasonably similar. For summer, you'd be at about 12% which is really nice and light.

      HJ

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  5. I understand your reasoning and think your conclusions are probably right. But what's a solo 115-lb hiker to do, short of hiring a Sherpa? There's no way that I know of to carry shelter, food and water for a typical 100 mile PCT section and have a pack that weighs 19.2 lbs. Realistically, most female hikers out there are carrying packs in your heavy to ultra heavy categories. And we're still doing 20 mile days. And having fun. :-)

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    1. Hi, Marie,


      Well, a couple of thoughts here:
      1. Smaller people are proportionally stronger than larger people. Yes, a larger person can lift more total weight, but a smaller person can lift more per pound of body weight than a larger person.
      2. "If it works, don't fix it". :) If you're out there with a particular package, and it's working for you, there's really no reason to change. I'm always trying to lighten up because I tend to enjoy hiking/backpacking more when I'm not overburdened. The ideas I've outline here are intended to get people thinking about how much they're carrying. They're not meant to be confining or restrictive.

      Lastly, I do know people who get out on the PCT with less than 20 pounds for a week, but those are SUL'ers and certainly not the majority. I got out for a week on the PCT in the Sierra this past summer with 29 lbs. That was about as good as I could do, but then I **eat** a lot. :)

      Take care, and thanks for reading,

      HJ

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  6. I just discovered your blog, thanks to a recent FB post about the chart. Thanks. I found it very useful.

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    1. You're welcome, Terry. Glad it's helpful.

      HJ

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