Framed vs Frameless Backpacking Packs: Matching the Pack to Your Base Weight

A frame is a rigid path from the load in the bag to the hipbelt on your pelvis. That is the whole function. A frameless pack has no such path, so whatever you put in it hangs off your shoulders and clavicles no matter how nicely the harness is cut. That is not a design flaw, it is the definition. Which means the choice is not a question of taste or of how minimalist you want to be. It is a question of what number the suspension has to handle on the heaviest morning of the trip.

The working threshold most people converge on is roughly 12 lb base weight for frameless. That figure is not a manufacturer specification, and none of the makers here publish a load ceiling, so treat it as a rule of thumb rather than a limit stamped on the pack. Below it, a frameless bag with a folded foam pad against your back carries acceptably. Above it, you are asking your trapezius and your neck to do a job that 200 to 400 grams of aluminium stay or carbon does considerably better, for the rest of the day, every day.

Terrain sharpens this. In the White Mountains the grades are steep and short, the tread is root and wet granite slab, and you spend a lot of the day stepping up rather than walking forward. Every one of those steps loads whatever is on your shoulders. Add the fact that resupply points are far apart for anything longer than a weekend, and you get long food carries stacked on top of it.

This is a comparison of published specifications. Manufacturer listed weight, listed volume, listed frame type, and manufacturer list price. Nothing in this guide is a test result. We have not weighed these packs on our own scale, loaded them, or field-trialled any of them, and I am not going to dress up spec-sheet reading as trail experience. What I can do honestly is arithmetic on the numbers the manufacturers publish, and point out where those numbers do and do not line up with each other.

I sorted by listed weight, 595 g up to 2200 g, and grouped by listed frame type. Anything outside that set is not published in what I am working from, and I do not guess: torso sizing ranges, fabric denier, hipbelt construction, stay material, and load carry rating are all absent. The last one is the frustrating omission, because a published maximum comfortable load would answer this article in one column of a table. Nobody prints it, so we reason from frame presence and from what the load itself weighs.

The number that matters is not base weight. It is total carried weight: base weight, plus food, plus water. Food runs about 1.5 to 2 lb per day for most backpackers depending on how you eat and how hard you are working. Water is 2.2 lb per litre, which is not a claim from anybody, it is just density. Base weight is the part you control with your wallet and your discipline. The other two are set by how far apart the resupplies and the reliable sources are.

Work an example. Ten pound base weight, five days of food at 1.75 lb per day, two litres on board leaving a road crossing. That is 10 plus 8.75 plus 4.4, which is 23.15 lb on your shoulders at the trailhead. Nothing about a 10 lb base weight makes 23 lb comfortable in a frameless pack. Now the same person on day five with an empty food bag and half a litre is at about 11 lb, and frameless is perfectly fine. The pack has to be chosen for the first morning, not the last.

Run it the other way. Fourteen pound base weight, two nights out, three days of food at 1.75, one litre carried between streams. That is 14 plus 5.25 plus 2.2, or 21.45 lb. Higher base weight, lower total. This is why base weight alone is an incomplete answer. If you want a single decision rule, it is this: if your peak total carried weight goes above about 25 lb, you want a frame, regardless of how light your base kit is on paper.

The Gossamer Gear Kumo 36 is listed at 600 g, which is 21.2 oz, in 36 L, list price $230.00. It is the smallest volume in this comparison, and that is the honest constraint: 36 L holds a genuinely light kit and two or three nights of food, and not much more. The volume does the discipline enforcement for you, which is arguably the point of a small frameless pack. Reason to skip it: if your base weight creeps past 12 lb there is no upgrade path, because you cannot add a frame to a pack that does not have one.

The ULA Equipment CDT is listed at 700 g, 24.7 oz, in 54 L, list price $200.00. That works out to about 13 grams per litre of listed capacity, the second best ratio of anything here, and it is the lowest list price in the whole comparison. Reason to skip it: 54 L of frameless volume is a trap for exactly the person who is drawn to it. The bag will physically hold 25 or 30 lb of gear and food, and absolutely nothing in it will move that weight onto your hips.

The Zpacks Arc Blast 55 is the interesting datapoint in the whole set: 595 g, 21.0 oz, 55 L, listed frame type internal, list price $375.00. It is the lightest pack here and it has a frame, which means it is lighter than both frameless packs while offering a load path to the hipbelt. On volume efficiency it is about 10.8 grams per litre, comfortably the best number in this comparison. Reason to skip it: it carries the highest list price of the sub-kilogram framed group, and the published specs say nothing at all about durability, abrasion resistance, or a load ceiling.

The rest of the sub-kilogram framed group sorts out cleanly. Hyperlite Mountain Gear Southwest 2400 is 824 g, 29.1 oz, 40 L, list price $349.00, which is about 20.6 grams per litre, the poorest ratio of any pack under 1200 g here. Reason to skip it: the Southwest 3400 adds 15 L for 92 g. Gossamer Gear Mariposa 60 is 879 g, 31.0 oz, 60 L, list price $300.00, giving 20 L more than the Southwest 2400 for 55 g more weight. Reason to skip it: 60 L is more room than a genuinely sub-12 lb kit needs, and empty volume gets filled.

Hyperlite Mountain Gear Southwest 3400 is 916 g, 32.3 oz, 55 L, list price $379.00. Set that against the Arc Blast at 595 g and list price $375.00 for the same 55 L and you are looking at 321 g, 11.3 oz, of additional listed weight at a comparable list price for identical published volume. Reason to skip it: it is the heaviest and highest-list-price pack in this group at a volume the lightest pack here also offers.

This is where most people actually land, and for good reason: base weights between 12 and 18 lb with three to five days of food are the normal case. Granite Gear Crown3 60 is 1100 g, 38.8 oz, 60 L, list price $199.95, about 18.3 grams per litre. Reason to skip it: it is 221 g heavier than the Mariposa at exactly the same listed 60 L. Osprey Exos 48 is 1140 g, 40.2 oz, 48 L, list price $240.00, which is about 23.8 grams per litre. Reason to skip it: that is the worst volume-to-weight ratio of anything under 1290 g here.

ULA Equipment Circuit is 1190 g, 42.0 oz, 68 L, list price $280.00, and 68 L is the largest listed volume in this comparison at 17.5 grams per litre. It is the obvious choice for a long unsupported food carry with a framed suspension. Reason to skip it: 68 L is a lot of room to fill, and if your base weight is genuinely under 12 lb this is more pack than the load justifies. REI Co-op Flash 55 is 1290 g, 45.5 oz, 55 L, list price $199.00. Reason to skip it: it is 695 g heavier than the Arc Blast at the same listed 55 L, which is close to a full day of food.

Osprey Atmos AG 65 is 2010 g, 70.9 oz, 65 L, list price $340.00. Gregory Baltoro 65 is 2200 g, 77.6 oz, 65 L, list price $359.95, the heaviest pack in this comparison. Judged purely on grams per litre these look indefensible, and if you only ever carry 20 lb they are. That is not what they are for.

The case for them is straightforward. Above roughly 30 to 35 lb total carried weight, the mass of a full framed suspension buys back more comfort than it costs. The Baltoro is 1605 g heavier than the Arc Blast, which is more than two days of food. But if the alternative is 35 lb sitting badly on your shoulders for eight hours of steep rooty climbing, the trade is worth making. Reason to skip the Atmos AG 65: 2010 g is nearly 4.5 lb before anything goes in it. Reason to skip the Baltoro: it is the heaviest here and its value only activates above roughly 35 lb.

Volume is not a comfort feature, it is a food-carry feature. At 1.5 to 2 lb per day, food is bulky on the first morning and gone by the last, but the pack does not shrink with it. Water is dense rather than bulky, so it barely affects the litre requirement while dominating the weight. That asymmetry is why volume and load rating are different questions.

A rough mapping from the volumes listed here: 36 to 40 L covers two or three nights for a light kit. 48 to 55 L covers four to six nights, or three nights with bulkier shoulder-season insulation. 60 to 68 L is for week-plus carries, winter-adjacent layering, or a hard-sided food canister, which eats volume in a way the litre number does not warn you about. The trap in every direction is the same: buy 68 L and you will find 68 L of things to put in it.

Do the arithmetic before you shop. Base weight plus days times 1.75 lb plus litres times 2.2 lb, evaluated on the heaviest morning of the trip you actually take, not the trip you imagine. Under 12 lb base with two or three nights of food, frameless is genuinely correct, and the CDT at list price $200.00 or the Kumo 36 at list price $230.00 are the two options here. Between roughly 12 and 25 lb total, a light framed pack in the 595 to 1290 g band is the answer. Above 30 to 35 lb, take the suspension and stop apologising for the weight of it.

The 595 g Arc Blast and the 2200 g Baltoro are both correct answers to different questions, and the difference between them is roughly two days of food. The wrong move is picking either one because of what it says about the kind of backpacker you are. Pick the frame that matches the load, and then work on the load.

Can I add a frame to a frameless pack? Not in any way these published specs cover. Folding a foam pad against the back panel is a common technique and it does stiffen things up, but it is technique, not a frame, and it does not create a rigid load path to the hipbelt. None of these manufacturers publish a load rating, so there is no number to point at either way.

Is base weight or total carried weight the number that matters? Total carried weight is what the suspension sees, so that is the number to design around. Base weight matters because it is the part you control by buying gear, while food and water are set by the route. Use base weight plus days multiplied by 1.5 to 2 lb plus litres multiplied by 2.2 lb, and evaluate on the heaviest morning.

Why is the Arc Blast 55 lighter than both frameless packs and still framed? I can only tell you that the published listed weights are 595 g for the Arc Blast, 600 g for the Kumo 36 and 700 g for the CDT, and that the Arc Blast is listed with an internal frame. The materials and construction that produce that result are not in the specs I am working from, so I am not going to speculate about them.

How much volume do I need for a five day food carry? Five days at 1.5 to 2 lb per day is 7.5 to 10 lb of food, and it is bulkiest on day one. For most light kits that points at 55 L and up. If a hard-sided food canister is required, plan on the 60 to 68 L end, because a canister does not compress or conform.

Are the prices in this guide current? No. Every figure here is the manufacturer list price and nothing else. This comparison does not track current or street pricing, does not follow sales or discounts, and does not maintain price history.