How to Choose a Backpack: Expert Tips for Finding the Right Size, Fit, and Features

What is the best backpack for you? As there’s no right model for everyone, it depends on what you’re doing, when and where you’re going, and how long your trip is. Knowing these things will help you determine how much stuff you need to carry. Additionally, you’ll also need a pack that properly fits and a suspension system that can handle your body and the weight you put on it.

Note that this article is geared mostly toward larger overnight backpacks. For information on smaller packs, read HOW TO CHOOSE A DAYPACK.

Choosing the Right Volume

Quite a few backpacks are on the market, ranging from small daypacks to full-size models designed for six months on the Appalachian Trail. Fortunately for your back, packs have been getting smaller over the past 20 years, due not as much to pack technology as advancements in camping gear. These days, tents are lighter, as are sleeping bags, stoves, and other essentials.

Pack volume refers to how much space there is inside the pack, measured in liters (or in some cases, cubic inches). Many large backpacks include the volume, in liters, within the name, such as the EMS LONG TRAIL 70 or The North Face Terra 35.

Which volume is best for you? That depends on what you’re using it for and what you need to carry.

Volume (Liters) Activities 15 - 30 Day hikes, school 30 - 50 Overnight (1-2 nights) 45 - 55 Weekend (2 -3 nights) 55+ Extended Trips (3+ nights)

Each of the capacities in the above chart covers a wide range. For instance, a backpack for an overnight trip may require anywhere from 30 to 50 liters. It all depends on whether you’re a minimalist or a more traditional backpacker.

Minimalist Backpacking

A minimalist, or ultralight, backpacker chooses the lightest, most compact gear, and would rather sacrifice stuff others might regard as necessities than carry a large load on his or her back. For this backpacker, the sleeping bag is likely insulated with the highest-loft goose down, and they’ll typically leave their tent’s stuff sack and stakes at home. And, forget about taking a change of clothing.

Traditional Backpacking

If you’re a typical backpacker (like 90% of us) who takes the normal amount of gear, choose a pack on the bigger end of the scale. For winter, you’ll need a much larger backpack to carry additional clothes, a warmer sleeping bag, and a heavier, sturdier tent. Also, if you’re bringing your kids along, figure on having to carry some of their food and gear.

Volume Conversions: Liters vs. Square Inches

Volume is measured in both liters and square inches. Either method works, and many backpack manufacturers provide the customer with both.

Liters (L) Cubic Inches (in³) 10 610 15 915 20 1220 25 1526 30 1831 35 2136 40 2441 45 2746 Liters (L) Cubic Inches (in³) 50 3051 55 3356 60 3661 65 3966 70 4272 75 4577 80 4882 85 5187

Length of the Trip

The longer you stay out, the more food and fuel you’ll need. In case you get wet, you also may need a change of clothing. Other than that, you should always bring along a tent, sleeping bag, sleeping pad, and stove, regardless of how many nights you’re camping.

Fitting the Pack: Determining Torso Size

Whichever backpack you choose, it needs to match your torso length. To determine your size, reach behind your neck, bend your head forward, and find the C7 vertebra: It’s the bone that sticks out the most on your upper spine. Next, locate the iliac crest. It’s the top of the hip shelf on the sides of your hips. Finally, have somebody take a cloth measuring tape to take the distance from the C7 vertebra down to the point of your back that’s at the same level as your hips’ iliac crest. This distance is your torso length.

For the pack to fit correctly, the distance from the top of the shoulder strap to the hip belt needs to accommodate your torso length. Keep in mind that torso length is not the same as height. A tall person can have a short torso, while a smaller person can have a relatively long torso. All full-size backpacks should list a torso-length range in inches.

Be aware that some packs have an adjustable torso length, meaning the distance between the shoulder straps and the hip belt can be lengthened or shortened, while others have fixed lengths. Also note that some packs are sold in multiple sizes, so the torso length can vary from size to size.

Selecting the Right Suspension

You’ve determined the proper volume and torso size. The next question is, will you be comfortable carrying the weight? This depends on the pack’s suspension. If you’re carrying 30 pounds with a flimsy hip belt, all the weight will fall onto your shoulders, and after a while, you’ll be in pain. To choose the proper pack suspension, it helps to understand the different components.

Hip Belt

When carrying heavy loads, the majority of the pack’s weight (as much as 80%) should be supported by the hip belt. Large backpacks designed for long-distance thru-hikes will use a heavily padded, relatively rigid hip belt that anatomically wraps around your hips. Smaller packs built for lighter loads have hip belts with less padding. A daypack designed for very light loads may offer only a webbing waist strap with no padding at all. Climbers and skiers may opt for a minimal hip belt to increase their freedom of movement.

Hip Belt Fit

To carry the weight, the hip belt should be centered over the hip bone (not the waist) and needs to be very snug. Once the hip belt is securely tightened, there should be a gap of 3 to 6 inches between the padded portions of the hip belt (over the buckle area). If the gap is too big or too small, you probably need a different pack or hip belt.

Molded Hip Belts

Osprey makes BioForm and IsoForm custom moldable hip belts that can be heated up and then molded to your hips to create a perfect fit. Most Eastern Mountain Sports stores have an oven that can heat the hip belt. Even without an oven, your own body heat will help mold the hip belt over time.

Shoulder Straps

The best shoulder straps curve to anatomically conform to your body shape. The padding doesn’t have to be very thick, because most of the weight should be transferred to the hip belt, but it should be comfortable to wear, with no chafing or pinching.

Strap Fit

While wearing the backpack, stand sideways to a mirror. The straps should conform to the top and back of your shoulders, leaving minimal or no air space between the pack and your body. In front, the shoulder strap padding should end about 2 to 3 inches below your arm pits. If the padding ends at or above your armpits, the straps are too short and you’ll need either another pack or different-size shoulder straps.

Load-Lifter Straps

These straps attach the top edge of the backpack to the upper portion of the shoulder straps. Adjusting them allows you to lean the pack toward or away from your upper body while keeping the pack in balance over your hips. Looking sideways, you should see the load straps forming a 45° angle to the top of the pack. If the angle is drastically off, you may need to adjust the torso length or choose a different pack.

Sternum Strap

This adjustable strap is located just over your sternum and connects both shoulder straps together to keep the pack steady.

Back Panel

This is the portion of the pack that presses against your back. To prevent the contents from poking you, all back panels should be padded. One drawback, however, is, it causes your back to sweat. To minimize this, some manufacturers build in air channels to allow some airflow. For even more comfort, the panel should also be made of a porous air-mesh foam.

Frame Components

An internal frame backpack provides rigidity and helps transfer the load onto your hips. Typically, frames consist of two aluminum or composite stays, also known as flat bars, running parallel to each other underneath the back panel. In some, the two metal stays cross in an X-pattern, while others use thin metal rods to create a frame, located either behind the back panel or along the perimeter of the pack.


A framesheet is usually made of plastic and is located behind the padded back panel so it’s not visible. It’s often used in combination with a metal frame to give the pack vertical and torsional rigidity.

Choosing the Right Suspension

The heavier the pack load, the more you need a substantial suspension. Here’s a quick guide.

Recommended Suspension (by packed weight):

Up to 10 pounds = minimal suspension; no frame, no padded hip belt10 to 20 pounds = light frame (rods), framesheet, lightly padded hip belt 20 to 40 pounds = moderate frame (stays or rods), moderately padded hip belt 40+ pounds = substantial frame (stays or rods), thickly padded hip belt

If a pack doesn’t fit correctly, nothing else really matters. It’s like a pair of boots—they can be the best ever, but they’re not much use to you if they don’t fit. Likewise, a pack needs to properly conform to your body and to allow you to carry the weight on your hips, not your shoulders.

Here are some quick pack-fitting pointers:

Your body’s torso length should be within the pack’s torso range.The shoulder strap should conform to the back of your shoulders.The load lifter straps should come up off the pack at a 45° angle.The shoulder strap padding should end 2 or 3 inches below your armpits. The hip belt should cover the top of your hip bones (iliac crest).The hip belt should support the majority of the pack’s weight.

Compartments & Pockets

Backpacks offer a wide variety of storage compartments, pockets, and sleeves. Some like a simple, streamlined pack with one main compartment, while others prefer having multiple places to stash their phone, food, water bottle, and other smaller items.

Main Compartment

This is the largest space in the pack. It’s where your tent, food, stove, fuel, and most of your gear are stowed. Most large backpacks allow access from the top. Some travel packs, plus many smaller daypacks, are panel loaders, providing access from the front of the pack.

Sleeping Bag Compartment

The sleeping bag is usually stowed within the bottom of the backpack. Many packs have a sleeping bag compartment that’s separate from the main space.

Other Compartments/Pockets

Top Lid—This pocket also keeps rain out of the main compartment. Front Pockets—Many packs have a large front pocket with a zippered closure. Others offer a “shovel” pocket, which accommodates a bulky jacket. Side Sleeves and Pockets—When combined with side compression straps, side sleeves can hold tent poles. Larger sleeves can also hold water bottles. Hip Belt Pockets—Nice for keeping small essentials within easy reach.

How you position the different items within the pack influences how comfortably it will carry. The heaviest items, such as water, food, the stove, and fuel, should be carried close to the back panel and at the vertical midpoint (or higher). The lightest items can be carried away from the body.

Pack Shape

Large backpacks should be tall and narrow. This allows for greater stability and freedom of motion.

Pack Fabrics

Nylon and polyester are the most popular pack materials. The higher the denier, the stronger (and heavier) the fabric. The bottom of the pack should be made of a high-denier fabric to withstand abrasions.

Women’s Packs

Besides coming in smaller torso sizes, women-specific packs should have shoulder straps and hip belts designed to better fit a woman’s body shape.

External Frame Packs

External frame packs have an easy-to-spot metal frame on the outside of the pack. Because they’re wider and carry farther away from the body, they’re less stable than internal frame packs. They’re easy to organize, however, and because of the space between your body and the pack, your back won’t get as sweaty.

Hydration Compatibility

Some packs have an interior sleeve specifically designed to hold a hydration bladder. A hydration-compatible backpack should also have a hydration port (a small built-in hole) to accommodate the rubber drink tube.

Compression Straps

Compression straps are found along the sides of the backpack. They cinch down, pulling the contents within the pack toward the body for better balance and stability.

Ski/Board Compatibility

A pack’s side compression straps can often be used to carry skis. Simply slip the skis inside the straps and then cinch the straps down. There are also a few packs that can carry a snowboard.

Spindrift Collar

This collar extends from the main compartment upward, letting you stuff more gear into the pack. Packs with a spindrift collar can often be stuffed beyond their stated volume.

Attachment Points

Bungee cords, clip-on points, daisy chains, and ice axe loops all allow you to strap or clip extra clothing and gear to the outside of your pack. Keep in mind that if you’re scrambling through bushes and other obstacles, these attachment points might catch.

Rain Cover

Unless you’re backpacking exclusively in the desert, buy a rain cover sized to fit your backpack. Because of all the seams, backpacks are not waterproof.