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New Math: Liters of the Pack

Shopped for a backpack recently? Then it's likely you've become acquainted with the new numerology that has infiltrated most pack names: the Deuter Futura 42 Pro; the Osprey Atmos 65; the REI XT 85.


Those numbers identify the volume available in each pack, expressed in liters -- the metric cousin of cubic inches.


Why liters? They're brief and easier to remember when comparison shopping. Most people find it's simpler to recall 65 liters than 3,967 cubic inches.


How do you interpret them? In general, ultralight specialists can manage an overnight hike with a pack volume of 50 liters or less. For multiday trips, 40 to 75 liters is a typical range. For extended trips, 65 liters or more is commonly recommended. 


New this year: Most stuff sacks are now offered with liter ratings. Instead of a 10" x 20" stuff sack, you'll find it billed as a 14-liter sack.


The just-updated REI Expert Advice article How to Choose a Backpack discusses liters in detail and offers some useful charts to help you envision how much space various items of gear occupy. What, for instance, is the exterior volume of a down sleeping bag (the REI Lumen +25°F regular) in its stuff sack? Roughly 13 liters. The Jetboil Flash Cooking System? About 1.3 liters.


As a lightweight/ultralight convert, here's a suggestion to anyone whose gear predates the lightweight revolution of the past decade: Begin assembling an adapt to using low-weight, small-packing gear, you'll gain the confidence to use it for longer trips. Check out the ultralight pack-bag-pad trio suggested in my article. All 3 add up to less than five pounds and 10 liters. Impressive.


Do you find the liter numbers in pack names to be useful? Leave a comment if you like.


Posted on at 6:00 PM

Tagged: backpacking, backpacks, cubic inches, extended trips, liters, multiday trips, packs, stuff sacks, ultralight and volume

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Hey that was a fantastic breakdown of the measurement system. I wish we could do that in more phases of American society. I'm 44 and I did learn the metric system in grade school but its one of those use it or lose it kind of things. I have lived in Europe and was forced to use the system there and I liked it (except for price per liter of gas). It would be nice to have liter measurement for gear that goes into the pack.

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Actually I'm against it. I just bought a new Osprey Kestral 68 and was confronted with the Liter versus the Quart issue while researching on line sources.. I almost mistakenly bought a too small of a bag, the Kestral 48 online....As noted in the original post the author tried converting Liters to Inches to show his point and maybe confuse the customer. Well, why not Quarts and Gallons instead of using Inches? Inches was a marketing failure from the onset. Nobody was actually measuring their pack that way except the Marketing people...Isn't converting Liters to inches like deceptive it is two different measuring units.... I mean Marketing has been looking for ways for years to deceive the buyer into believing he is getting more for his money when he is getting less. Liters is perfect for that....

I think it is just a way for Marketing people to confuse the customer because it is not standard in this Country yet and people are thinking they are buying more when it is less... I was so glad I went to the Store first, after I looked a my Metal Liter Bottle, which is a joke, and compared it to my Quart Nalgene bottle, because when one says say, 48 liters, its sounds like a lot of space when in reality it is a tiny bag...and that is what I believe the Marketing Maggots hope you will believe and don't figure your buying less for more which is really what you are doing.... And who cares what the Europeans's just being done to Market products on a world wide level that is all, so instead of having to market two sets of information they only need one...Saves REI money, which is sort of like Banks trying to do away with Checks, it benefits the Bank, but the savings is not passed on to the customer... Slight of hand? or Obama type and the same...


Point well taken, on all accounts. I agree with most of your points. I still like the metric system though.


Dude is this a joke? 'cause it made me laugh. The liter bottle was a joke compared to your burly 'merican quart bottle? You do realize that a liter is BIGGER than a quart? And the metric system is just a big marketing conspiracy, as confusing people is good marketing, and it all must be President Obama's fault too right? Actually, I'm a lot smarter than all that. Not only do I "get" the metric system without ever having lived in Europe but I figured out REI's real "slight" (the word you want is actually "sleight") of hand... Bigger volume just means extra air! REI is trying to sell you air! More volume, more air, more expensive! I refuse to pay extra for all the air! I'm looking for the smallest volume of air possible so I can beat REI's Obama marketing slight of hands! I win!


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