Pack volume that can be shared with a partner

Question

A partner and I are hoping to hike over a 4 - 5 day trip in Glacier National Park in August (hot days and cool nights).

We are trying to decide on backpacking packs size.

We can share a tent and cooking supplies (and other small things).

We currently have this tent (REI half dome). (My estimates are this is about 19 L)

We will each have one sleeping bag like this (REI trailbreak 30) (About 6 L each).
We feel we can each go without a sleep pad if we do not have the space for it.

Then maybe something like a Jetboil and a water filter.

Of course there is clothes (rain stuff too), food, and other small items to pack along.

Now, normally people seem to recommend about 60L for a pack for 3-5 days. However, I don't know if these take into account the items that can be shared among a pair.

Instead, I was imaging a womans 45L pack for my partner and a mens 55L for myself.

So my question is, what packs should one get if they are backpacking with a partner on a 5ish day trip?

Answer 1

That 60 l figure is a middle ground. There are ultralight backpackers who could use a lot less, but that means spending huge amounts on minimalist kit, and refining your setup over time. I come more from the "be prepared" end of the scale, partly because I live somewhere with very changeable weather, and have a very old but very nice 60-75 l pack. That means it expands upwards, making it rather tall at the biggest size. I used it a lot trekking in groups of 2-3, with an appropriate size of tent, and one stove per group.

With up to about 3 days between resupply stops, this was plenty, even when we had to re-share the load within a group of 3 to help someone who was struggling. Sleeping bags are smaller now (when compressed), and tents can be. Sleeping mats have become much smaller (e.g. mine is 0.8 l) or foam ones can be strapped on the outside. Some form of sleeping pad is essential in most conditions; a sleeping bag is very poor insulation underneath, even if the ground is comfortable.

If you may be resupplying a small group in the field, you can't always optimise item sizes, and if you can only get huge bags of pasta and large loaves of bread, you'll struggle if you were totally full when you left home.

I suggest that your thought of 45+55 l between the 2 of you is a little small. Food, water (even if only for the day), and clothing make up a significant amount of the bulk, and the amount you need is per person; you'll also use a bit more fuel with 2. Another 5 l each would go a long way. It's impossible to completely avoid all gaps in packing so if you measure every item and add up the volumes, you'll underestimate your requirement; with practice you can get the gaps pretty minimal and still have the items you most need accessible.

Answer 2

When it comes to selecting your packs, just forget about gear sharing aspects. Size your packs to be capable of supporting each of you as though you are going individually.

Two major reasons:

1. Is this going to be the only trip you use these packs for? Probably not. Size them so you can go on other trips, as a couple or individually. A 45L is going to be roomy for day trips or pushing the limits for ultralight extended trips. A 55 is also going to be tight for extended trips but barely manageable in places with favorable weather.

2. The volume savings from sharing gear really aren't all that substantial. I've backpacked with friends and my wife, sharing gear, and you really don't save a lot of volume. You can share your tent, cooking gear, and emergency gear. Pretty much everything else each of you needs to have. Cooking gear and emergency supplies don't take up much room to begin with. I store my tent on the outside of my pack, so a reduction in its size doesn't make any difference anyway. If you do store your tent in your pack, you generally can only split fabric and poles, and the poles don't take up much space, so you aren't saving a whole lot.

Splitting tent, cooking gear can have significant benefits with regards to weight, but volume it really isn't a big difference, in my opinion. Certainly not enough to go with a 45+55.

I would get at least a 60L pack for each of you, minimum. The weight difference between a 45 and 65 is not going to be significant in the pack weight, it's better to have a little extra margin.

Yes, owning a larger pack does have the risk of "I've got the space, might as well bring this one thing" and before you know it you're packed full anyway. But, you can avoid that with some self-restraint. But, if you can't fit all your necessary gear in too-small a pack, there is very little you can do.

Answer 3

In addition to the good answer by @ChrisH. I'd like to add:

You don't loose much by bringing backpacks that are a bit to roomy. They might weigh a little bit more, but the difference between a 45l and a 60l pack is probably not very significant compared to your total weight, especially if you are new and and your gear is not heavily optimised.

However, what you gain by having a roomy backpack is comfort.

Packing your backpacks in an optimal way on your kitchen table before you start out for the trip is great fun. Having to play optimisation Tetris for an hour every time you break camp can cost a lot of nerve, especially considering rain, cold, mosquitoes, etc..

Therefore my suggestion would be: when in doubt I would go for the bigger pack.

Answer 4

I think you need to take 60 liters. It won't be much costly for you but you will have enough place for everything you need while camping. Modern backpacks are really lightweight and it won't be more difficult to wear 60litres than 55. And you can need it later when you will go camping alone. It's a really bad idea not to take a sleeping pad because there is a big risk to get cold.