Maybe I’m just becoming more aware of it, but recently frameless packs without hip belts seem like all the craze. Trail celebrities like Lint have been preaching it for years, but more and more ultralight companies are putting out streamlined packs in the 30-40L range designed for sub-10 pound base weights: the MLD Burn, ZPacks Nero, Zimmerbuilt Quickstep, KS Ultralight KS 3 & KS 4, and the Pa’lante Simple Pack are just a few. Yes, some of those do have “hip belts,” but their function is to keep the pack secure, not to carry weight like a traditional hip belt.

It’s hard to know if the frameless, hip belt-less pack is right for you without trying one, and like most ultralight gear you have to order this stuff online. Here’s a (convoluted and mathematical) way to test if a frameless, hip belt-less pack might be for you:

Step 1: Calculate your baseweight, \(BW\).

Step 2: Calculate the difference, \(\Delta\), between the weight of your current pack and a frameless hipbelt-less pack (most weigh ~10oz, so we’ll use that as an example):

Step 3: Using the numbers from Step 1 and Step 2, calculate your Max Pack Weight, \(MPW\), with a frameless hip belt-less pack, where \(days\) represents the maximum number of days between resupplies and \(L\) represents the total liters of water capacity required:

For example, let’s say your base weight is 10 lbs and you would swap your old 3lb backpack for a 10oz (0.625lbs) pack. You also plan to hike for 4 days while carrying 2 liters of water:

Step 4: Load up your existing pack so that it weighs as much as the result of Step 3 \((MPW)\).

Step 5: Go hike but do not clip your hip belt. Just let your hipbelt dangle and put all that wonderful weight on your shoulders.

If you don’t mind hiking all day with that amount of weight on your shoulders, or you enjoy it immensely as your consumable weight lessens, then a frameless hip belt-less pack might be for you. On the other hand, if you can’t stand that much weight on your shoulders, then you should probably stick to a more traditional pack. Pack fit varies and this is only an approximation, but it’s an easy way to explore lightening your load without having to take the plunge and splurge on a new, potentially useless pack.

Who said you wouldn’t use your high school algebra in the real world?

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Fun story: I first conducted this experiment by accident on the PCT. Walking out of Sierra City, I was too stuffed from all the food I had eaten to clip my hip belt, so I hiked without it. I haven’t clipped a hip belt since.