How accurate are manufacturer volume numbers?

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  • #1266786


    I was at an EMS today and compared a number of packs side by side. I'd undo the straps, bindings and zips and fill out the packs with "stuff".

    Several times, I noticed two different packs from different manufacturers, whose cubic in. volume were listed about the same, where one was almost twice the size of the other. I even called over the manager to see if my eyeballs were just having a bad day. He smiled after comparing the manufacturers' pack volumes.

    Isn't there some industry norm by which they accurately measure volume? I understand that exterior pockets do add to the volume, and maybe even deceptively so, but the overall difference was striking at least with the packs I looked at.

    What's up with this?

    Ken Thompson
    BPL Member


    Locale: Right there

    Not accurate. Marketing at work. All specs are spun.

    BPL Member


    Wildly inaccurate — esp. the wider-known brand names!! Same with weight specs and warmth ratings.

    The boutique UL gear makers tend to be much more honest — likely because they know that many of their customers are UL fanatics who will verify!

    gavin wenyon


    Never judge a pack by its stated size, Just make sure your gear will fit.

    Maybe they should make a standard for the measuring process, just like sleeping bags. At least that would give consumers a better idea on what to look for. Ive seen tons of variation between brands.



    The difficult aspect to making sure things fit/measure up is that often I am buying online and waiting to "try it out" after I buy it when it arrives.

    I love the cottage industry that the internet has spawned but, at the same time, I detest buying without having the opportunity to know what on earth I'm buying.

    Were measurements accurate you could narrow down your choices based upon them. If there is little, or no, reliance upon what a manufacturer asserts then it's basically a roulette wheel. Very frustrating.


    James holden
    BPL Member


    in the recent BPL tests the packs that were closest to their claimed volume were jansport and montbell

    the least closest were ULA, golite, GG and rei

    part of it is a lack of standard measurements or adherence to such … the other problem is that its basically a marketing statement

    one company produces a "50L" pack … so another company does as well

    Jason Delso
    BPL Member


    Locale: DFW

    There is an ASTM standard for measuring volume, but adherence (and then accuracy) is sometimes lacking. BPL article

    Greg Mihalik


    Locale: Colorado

    Adherence is lacking, as is protocol.

    When measuring a Mariposa Plus you immediately notice that the pack is constructed as a cylinder.

    When measuring ULA Ohm you notice that the pack is constructed a rectangle at the bottom, which can transform into a cylinder at the top. But, the way I pack it, the top retains its rectangular section. (I like to keep things close to my back.) So, the way it gets measured can give you more volume than the way I use it.

    The same can be said of the Mariposa Plus. It has a large volume, but you may or may not be able to use it Effectively, if your pack items force it into a rectangular cross section.

    So even with a "standard" the resulting volumes can still be misleading.

    But, packing peanuts or ping pong balls will always yield a better result than marketing BS.

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