Big trips—whether it’s a week of backpacking or committing to a thru-hike—call for a big pack. Having the capability to carry everything you need with you is freeing, but it can also be heavy. Literally. That’s why the right multi-day pack needs to be balanced and well-fitting.

Everyone moves through the mountains differently, so choosing a multi-day pack that works for you is highly dependent on how you pack, how quickly you travel, how much weight you prefer to carry, and the type of terrain you’ll be in. For people who have ultralight sleep systems, basic food supply, and minimalist gear, a 30-40 litre pack (which, for some, is the perfect size for a daypack) can be the right fit for longer objectives.

But for most objectives that require extra food, layers, cooking and sleep systems, a pack with a capacity between 40-70 litres is ideal. When it comes to packs with that kind of carrying capacity, support and fit is key. Arc’teryx uses technologies like thermoformed frame sheets and ultralight aluminum structural elements to provide essential support and reinforcement to packs without adding unnecessary weight. Along with frame elements that have an impressive strength-to-weight ratio, fit systems are a critical component of multi-day packs that can go the distance. Hip belts, shoulder straps, and sternum straps on Arc’teryx packs have multi-directional fit adjustments, creating customized fit systems that allow for a comfortable carry for most bodies.

Because a multi-day pack is the kind of pack that is there through it all, durability and weather-resistance is critical. Specialized fabrics and finishes—like Cordura ripstop nylon and DWR (Durable Water Repellent) treatments—ensure that you can rely on your pack to go the distance.

How should a women’s multi-day pack fit?

A women’s pack for long trails and thru-hikes should comfortably fit with the hip belt resting at the top of the high point of your hip bone (the iliac crest) and the shoulder straps hugging the tops of your shoulders, with contact through just the tops of your shoulder blades. With these two points of contact, you can confirm that the length of the pack is correct. A pack that’s too small will fit with the shoulder straps hugging all the way down your back and the hip belt hitting on your torso near your belly button instead of your hip bones. A pack that’s too large will have gaps between the shoulder straps and the tops of your shoulders, and the hip belt will rest across your hip bones.

How much should a women’s backpack weigh for a 3-day hike?

A general rule of thumb for multi-day hikes is that your pack shouldn’t weigh more than 20% of your total body weight. So if you weigh 72.5kg (160lbs), your maximum pack weight should be around 14kg (32 pounds). If you weigh 54kg (around 120lbs), your pack should weigh around 11kg (24lbs). Of course, how much you need for a 3-day trip depends on your style of travel, the conditions and terrain, and personal preferences. But keeping this weight guideline in mind can help determine when you need some ultralight gear to shave weight off your pack, or when you can carry that extra summit treat.