Ultralight backpacks tend to be a lot lighter than more mainstream backpacks with internal or external frames and generally fall under 2 pounds in weight. There are exceptions to this and some UL packs are heavier than two pounds, but it’s a pretty good rule of thumb.
Historically, ultralight backpacks were mostly frameless, but a lot of the UL packs you can buy today come with optional pack stays, which effectively put the “frame back in frameless.” These are aluminum or carbon fiber rods that slide into pockets in the back of the pack and stiffen it up, enabling you to carry heavier 25 to 40 pound loads. They also transfer more of the pack weight off of your shoulder straps and onto the hip belt.
But I think the thing that sets UL packs apart from other packs is their design, how you pack them, and how you “interact” with them during a backpacking trip. But first, some backpack anatomy:
Most UL packs have the same basic design:
- A large main compartment
- A roll top closure, and not a top pocket or floating lid
- Two side pockets
- A large open front pocket, often made out of mesh or solid fabric for better durability
- Lots of attachment points around the perimeter of the pack
When you pack a UL backpack (for 3 season use), you put all of the gear you might need during the day into the outside pockets of the pack including water bottles, rain gear, snacks, hat, compass, map, camera, and whatever water purification system you prefer. Everything else gets packed inside the main compartment and is closed off for the rest of the day until you get to camp. Many people who use UL backpacks also store their shelter on the outside of their packs, so they can set it up before they have to open the main compartment of their pack. This helps keep your sleeping bag and clothing dry if you need to set up your shelter in the pouring rain.
By placing everything you might need on the exterior of your pack you can move very quickly during the day, without having to take a lot of breaks to find stuff buried in your pack. The convenience is addicting and I struggle with internal frame packs, where nearly everything you carry is packed inside the backpack and requires longer stops so you can dig it out.
One of the design elements that I like best about UL packs is the ability to set up ad hoc rigging systems using the external attachment points. It’s very handy if you have a long tent or fishing pole you want to secure to the side of your pack, crocs, a platypus – if you need to carry extra water for a stretch, or a sleeping pad. If you carry an external frame backpack, you also have this kind of flexibility, but I don’t find it that much on internal frame packs, which is a shame, because it really stretches the utility and value for money that you get on packs that can be used in many different ways.SectionHiker is reader-supported. We independently research, test, and rate the best products. We only make money if you purchase a product through our affiliate links. Help us continue to test and write unsponsored and independent gear reviews, beginner FAQs, and free hiking guides.