measuring/estimating cubic inches?

Any clever ideas for measuring/estimating the cubic inches of your gear? I'm thinking about an internal frame pack to replace my old external frame and would like to get an idea of what size I want to look at. My gear has pretty much stabilized at about 25 lbs base weight. Of course, that includes an awkward bear canister.

Best solution is to find the model of your old backpack and look up the specs online ...

Failing that, I don't know. If you can reuse the water afterwards for watering plants or something, getting a contractor bag and filling it with water could work, then measuring out the water in whatever measuring devices you have available (a funnel and gallon jugs if nothing else). Awkward/heavy, though, and could get wet/messy ...

To get in the ballpark, at least, stuff it full of whatever --- clothing, newspaper, etc, and take external measurements to get at least a reasonable approximation.

Kind of a fun challenge!

Wait, re-reading your post, are you asking about cubic inches of each individual gear item?

I wouldn't go that approach at all. Various things are more or less compressible, so it's a tough call that way. Better IMO is to fill your existing pack with that gear, see how much room is left over, and then get the capacity of your existing pack.

Fill it with packing peanuts, including pockets, etc. empty the peanuts into a box, then measure and multiply to get the volume. (231 ci=1 gal).

That will give you a ballpark to begin comparing in. If you regularly strapped gear to your external frame pack, be sure to include that in your calcs.

Cheers,

Or you could measure your pack frame multiply H x W x L ( most old framed packs are square)this will give you cubic inches, at least close enough for size estimation.

Are you trying to measure the volume of your existing pack, or the volume you need to hold the gear you have?

If it's the volume of the existing pack, the packing-peanut method should work well.

If it's the volume of your stuff, I'd suggest that you get a large box, and put your gear in it (compressing anything that would be compressed in the pack, like your sleeping bag.) Then mark the inside of the box at the height of the load. Empty it out, then measure length, width, and depth, and do the math. (Divide cubic inches by 60 to get an approximation of the liters.) I'd allow some extra volume when shopping for packs, simply because you'll end up with some unused space (such as in the lid) because gear won't fit in the pack like it does in the box.

Packing peaanuts will give you a crude estimate. For real accuracy, employ organically grown , fair traded flax seed harvested by maidens during the night of the harvest moon and aged in oaken barrels for fifty years.....

To be somewhat more serious, somewhat similar techniques are used successfully to measure irregular volumes like the interior of skulls or ceramic vessels.

Ha that's great. Or you could use rice, beans, cat litter, sand, any other imaginable small object.

Ha, WONDERFUL suggestions. Since I'm trying to find out how big a pack I need to carry all my gear, I may go with the "pack a box" estimate. That is, until I can plan to check out the flax seed harvesting operation... By full moon, you say....

BTW, the Rick's way is the way many manufacturers measure their packs.(some use ping pong balls)
Because most packs have very irregular shapes it is pretty much impossible doing it another way.
As far as using the given measurements (manufacturers specs) take those with a grain of salt because they can be rounded off (IE 50/60/70 L) or simply include the theoretically possible volume of the pockets.
Theory and practice here differ because in most cases you cannot get the same volume in those pockets when when the pack is also full compared to when it's empty...
You could always make several 5-10 L bags filled with those polystyrene balls and take those to the shop and see if they fit inside a pack.

Find an appropriately sized cardboard box. Put in all your gear plus equivalent in weight and bulk of a week's food. Level off the top. Measure volume (length x width x height). If you want liters, for rough estimates, 1 liter equals approximately 60 cubic inches. The weight is also important because pack manufacturers specify a maximum weight (subtract 5 lbs. from their number).

Be sure to have the gear available to load into the pack when you get it! That's why it's strongly recommended that you buy the pack last. You should load up the pack with all our gear and take a couple hours' "hike" around the house while you can still return the pack.

Pack your currect pack with the gear and consumables you would ordinarily use. Go to REI or similar. See which pack will take all your gear and try walking around the store with it. BTW, REI have nothing in cubic inches any more.

REI have nothing in cubic inches any more.

As long as they sell packs they will have them in cubic inches...



100 cu = 1.639 L

This is not entirely true, at least the Product Information Guide for backpacks that is in the physical stores list all the backpacks that REI carries, and the Liters and Cubic Inches for each (including weight in oz., size, etc.)

Oops.My error. I was just looking at the pack names rather than the descriptions.

Since a lot of pack makers are using liters, it's useful to know the conversion.

BPL has done some reviews of backpacks that show that most manufacturer's volume measurements aren't very accurate anyway, so the 1 liter = 60 cubic inches is close enough. (As we used to say when I worked for a government contractor, "Close enough for government work.") However, it's far, far better to try the pack out with the actual gear you'll be putting in it. The pack has to be comfortable for you carrying your gear, and there's only one way to find that out!

Yes.
Just yesterday I spotted a comment from a guy saying " how comfortable" a certain pack is,for him, carrying 40lbs.
Problem is: that pack is uncomfortable (for me) at 30 lbs.
Comfort is of course related to what we know or are used to.