Last Updated: April 3, 2023
Anatomy Of A Backpack: All About Backpacks
Are you confused by all the different terms that are used to describe parts of a backpack? If so, you are most definitely in the right place! This layman’s guide to the anatomy of a backpack covers everything you need to know about backpacks, from what compartments are to how you can utilize load lifter straps.
So, if you want to buy yourself a brand new backpack but you’re not sure whether to go internal or external frame, laptop sleeve, or hydration compartment or if you should buy something without an adjustable harness, we’ve got you! Read on to learn about the different parts of backpacks and what they are used for!
Table Of Contents Show All
Backpack Frames
The frame of a backpack is what helps it retain its shape even when it is empty. But, there are a few different types of backpack frames, and that’s what we’ll cover in this section!
Internal Frame
Internal frames are common in large-capacity bags for backpacking and overseas travel. The purpose of an internal frame is to transfer the backpack load onto your hips and improve your overall stability.
Most internal-frame backpacks have multiple load adjustment straps, allowing you to get a precise fit for the most comfortable experience.
External Frame
External frames were common in outdoor backpacks before internal frames were a thing. They are bulkier and heavier than internal frame backpacks, but they do an excellent job at transferring the backpack load onto your hips.
Additionally, packs with external frames often feature a lot of space between the bag and your body, meaning great ventilation. Plus, it’s possible to attach items to an external backpack frame, which isn’t really an option with internal frames.
Frame Sheet
Most backpacks have a frame sheet of sorts. This is very common in smaller backpacks that are designed for everyday use and travel. A frame sheet makes a backpack more rigid so that it can stand upright even when totally empty. Frame sheets help distribute the backpack load more evenly, and they’re often paired with some type of foam to ensure a comfortable carrying experience.
Frameless Backpack
Frameless backpacks are bags that do not have any type of frame or frame sheet. They’re lightweight and packable, but not the most comfortable to carry around. Frameless backpacks are compressible, and they can usually be folded to fit into your pocket, even if they normally have a capacity of 50+ liters.
Compartments & Pockets
Backpacks can have several different compartments with specific purposes and dozens of pockets. In this section, I’ll cover the types of compartments and pockets that are common in backpacks.
The Main Compartment
A backpack must have a main compartment to be considered an actual backpack. The design of the main compartment varies drastically depending on the size, type, and quality of the bag.
Some backpacks have a main compartment that is empty, others will have a simple sleeve or two inside, and there are backpacks that have compartments within the main compartment. It all depends on the type of backpack you’re buying – a small bag for school is more likely to feature an empty main compartment, while a backpack for travel more often has additional pockets and dividers inside.
It’s common for backpacks to have laptop sleeves inside the main compartment, especially if we’re talking about versatile bags that are designed for various adventures.
Organizer Compartment
Many backpacks will have an entire compartment dedicated to organizing your smaller belongings. These compartments are usually on the front panel, and they’re much smaller than the main compartments.
The classic organizer compartment will have multiple open and closed pockets that vary in size, as well as other attachment points. Some organizer compartments have pen holders, others have card slots, and most of them will have a key clip near the top.
Rain Cover Compartment
A lot of backpacks have dedicated compartments where a rain cover is stored. This is common in backpacks that are designed for various outdoor activities like hiking and trekking, but also in some everyday and travel backpacks.
Rain cover compartments are usually just small pockets that fit the rain cover and not much else. Some can be used to store other small items, but there are also backpacks that have a rain cover sewn into this compartment, so you can’t really use it for much else.
Hydration Compartment
A lot of backpacks have a dedicated hydration compartment or a hydration sleeve. These are usually bags designed for outdoor adventures that require you to stay hydrated like hiking, cycling, trekking, etc.
Hydration compartments are very common, and they’re usually versatile. In most cases, a hydration sleeve will double as a laptop sleeve, so you can have great functionality in the bag no matter how you are using it. One way to figure out if your backpack has a hydration compartment is to look for a hidden hole near the top of the compartment.
If the hole exists, it’s there so you can pull the hydration bladder hose through it to secure it to your shoulder strap. If there aren’t any holes near the compartment in the back, it’s likely just a simple laptop compartment.
It’s worth noting that hydration compartments can be internal and external. External hydration sleeves are usually located just behind the back panel and they’re common in hiking and trekking backpacks. Backpacks with external hydration sleeves often feature drainage points on the backpanel, which keep the items inside the other compartments protected in case the reservoir ruptures.
Laptop Compartment
Some backpacks have compartments that are designed specifically for laptops. These can be small compartments for 11” devices, or they can take up the majority of the bag and be capable of fitting several 17” laptops. It all depends on the type of the backpack – a laptop backpack will have a more elaborate computer sleeve, while a travel backpack might not even offer an entire compartment for your electronic device.
Laptop compartments are usually padded – at least the good ones are. The padding absorbs shock, so in case you accidentally drop your backpack, there’s something to cushion the device. Good backpacks will have a Velcro strap or something similar that ensures the laptop stays in the padded sleeve no matter what.
Laptop compartments can have additional pockets, sleeves, organizers, and they can open in many different ways. It all depends on the type and quality of the bag – the only thing they all have in common is that they’re designed to hold portable computers.
Quick Stash/Stretchy Compartment
A lot of backpacks feature a stretchy compartment on the front panel that’s usually secured to the bag with a buckle. Some brands call it a shove-it pocket, others say it’s a quick-stash compartment, but the function and design are always the same. The stretchy fabric lets you keep bulkier items in this compartment, making it perfect for carrying spare layers of clothing.
Sleeping Bag Compartment
Hiking, backpacking, and camping backpacks usually feature a dedicated compartment for a sleeping bag. It’s often located on the very bottom of the bag, and in most cases, there’s a zippered divider inside that lets you access the main compartment through it.
Some backpacks allow you to connect the main and sleeping bag compartments, while others prefer to keep this a pocket that’s entirely separate from the bag’s other compartments.
Shoe Compartment
Shoe compartments are often found on backpacks and duffel bags for gym and sports. They usually feature a waterproof lining and it’s common for them to have some sort of ventilation. The size of shoe compartments depends on the bag – usually, they’re designed to fit shoes up to a certain size. If you wear really big shoes, it’s important to look for information about the exact size of the shoe compartment.
Side Pockets
Side pockets are found on most backpacks, regardless of the size and purpose. The most common type of side pockets is stretchy pockets, which can hold water bottles, tripods, pocket umbrellas, and other small items. It’s possible to find backpacks with zippered side pockets, but they’re not as common.
One thing worth noting is that the functionality of the side pockets depends on whether the bag has compression straps. If a backpack has compression straps above the side pockets, you can store some bulkier items in them like tripods and trekking poles. The compression straps will secure them in place and ensure they don’t accidentally fall out.
Scratch-Free Pocket
A lot of everyday backpacks feature a scratch-free pocket. It’s usually just a small pocket located at the top of the bag, near the main compartment zipper. More often than not, it’s meant to hold your smartphone and sunglasses – the things you want easily accessible, and away from items that could scratch them. A scratch-free pocket can be lined with fleece or some other soft material, but that’s not always the case.
Hip Belt Pockets
Hip belt pockets are common in large-capacity backpacks for outdoor adventures. These are small pockets that are located on either side of the hip belt. You can access them while you are wearing the backpack, and they’re perfect for those items that you want to have easily accessible while you’re trekking through unknown territories.
Hip belt pockets can be big enough to hold a smartphone and snacks, or so small they’ll barely fit a GPS tracker. It usually depends on the size of the bag and its hip belt. It’s worth noting that hip belt pockets are only seen on backpacks that have thick, padded hip belts and not on those that feature just plain webbing straps for the waist.
Backpack Opening/Closure & Access
Roll-top closure, floating lids, and side access are phrases that are often used to describe backpacks. I’ll explain them in this section, and tell you all about the different types of backpack opening, loading, and access.
Roll-Top Closure
Some backpacks feature roll-top closure. This means that the top of the backpack can be rolled down and then secured in place with a buckle. These bags are generally considered safe, but they’re usually top-loading backpacks, so they’re not the most convenient for everyday use.
TSA-Friendly Backpacks
Some travel backpacks have a TSA-friendly opening of the laptop compartment. This means that the laptop compartment can be unzipped to lie flat when you’re passing through TSA checkpoints so that you don’t have to take your device out of the bag at all. The best backpacks have a mesh sleeve so that your laptop is visible when the compartment is opened.
Clamshell
Backpacks that open up clamshell-style have a wide zipper that allows you to open a backpack like a flip phone. Both sides lie flat when a backpack is open and the items inside are easily accessible. This type of backpack opening is most common in everyday, travel, and laptop backpacks.
Suitcase-Style
Suitcase-style opening and closure are common in travel backpacks. These backpacks usually open up like a book to expose double packing compartments, just like with suitcases. They’re not convenient for everyday use but they are an excellent alternative for travel, especially since most of them have the same capacity as traditional suitcases.
Top-Loading
Top-loading backpacks are those bags that have a main compartment that opens up only at the top. You pack them bottom-to-top, meaning that the stuff that goes inside the backpack first is the least easily accessible out of the bunch. Sometimes you can access the items at the bottom through other zippers on the bag, but that’s not always the case.
Top-loading backpacks can also have floating lids, but more on that later. This style of backpack is most common with larger bags designed for trekking and backpacking.
Front-Loading
Most backpacks are front-loading. These are classic backpacks that let you open up the main compartment as much as you want, and pack things inside in any order you want. Provided that the zipper is wide enough, you can easily access the items that are at the bottom of the main compartment even when it’s fully packed.
Floating Lid
Floating lids are common in large-capacity bags for trekking and backpacking. Those backpacks usually feature drawstring closure with a detachable lid on top. The lid doubles as a mini-daypack, allowing you to leave the huge backpack at camp and take just the necessities with you for a little while.
A floating lid usually has one main compartment and a couple of other smaller pockets, so it’s still possible to stay organized even with the small capacity.
Side/Bottom Access
Additional access points are common in large-capacity backpacks. If you have a 60liter+ bag, you need more than one access point to be able to use it properly. Imagine having to take out more than half the things inside, just to get to that one pair of shorts at the bottom.
That’s why a lot of big backpacks have access zippers on the sides and bottom. You can easily get to the items you packed first, without having to unpack the entire bag.
The Back System
A backpack’s back system is crucial for your carrying comfort. If it’s not properly padded, you can feel the contents against your body. And if it lacks ventilation, you’re going to sweat bullets on hot days.
Back Panel
The back panel is one of the most important features of a backpack. Cheap backpacks don’t even have a proper back panel – instead, they’ll just feature a slightly thicker layer of the same material the rest of the bag is made from. The pricier the backpack the better the back panel.
The back panel is important because it’s the only thing separating your body from the items in the bag. If you’re carrying a laptop or something similarly bulky inside the bag, there’s a chance it will poke you in the back and make you uncomfortable. This will only happen if the back panel is thin – with sufficient padding, you could carry anything in the backpack and you wouldn’t feel it.
Back panels can be designed in a variety of different ways with an emphasis on particular features. For high-capacity backpacks, the main priority is to create a comfortable back panel that will let you carry the backpack for hours and even days without getting tired. For smaller backpacks meant for fast-paced outdoor activities, back panels are usually made to be super-breathable to prevent excessive sweating.
Padding
Almost all backpacks have some sort of padding in the back. The exceptions are the ultralight packable bags and the really cheap backpacks that you shouldn’t be looking at anyway.
Backpacks usually feature foam padding, and in most cases, it’s EVA foam. The padding creates a barrier between the contents of the bag and your body, ensuring that you’re not getting poked in the back by a random object in your backpack. Padding is crucial for carrying comfort and bags without it are not meant to be worn for more than a couple of hours at a time.
Ventilation
A good back panel is sufficiently ventilated so that you’re not sweating bullets if you’re wearing the pack and moving around while it’s hot outside. Backpacks can be ventilated in a variety of different ways, but they usually just feature breathable mesh on the outer part that stays in contact with your body.
Some backpacks that are meant for fast-paced activities have more elaborate back panels with a focus on ventilation. These are usually designed to be suspended when worn so that the padding is not even touching your back all the time.
In addition to that, some backpacks guarantee breathability by incorporating airflow channels into their design. A backpack can have multiple foam panels in the back with channels between them. The channels let air circulate, which helps your body breathe and minimizes sweating.
The Straps
Every backpack has straps. Some simpler backpacks have just two shoulder straps, while the better and more elaborate bags will have dozens of different straps on the bag.
Shoulder Straps
Shoulder straps the limbs of a backpack. Every backpack must have them, otherwise, it’s not a backpack at all. The size, shape, and thickness of shoulder straps depend on the bag.
Basic backpacks that you can get at a grocery store for $10 usually have just thin, rectangular shoulder straps. Their only purpose is to hold the bag on your torso, and if you make the backpack too heavy, the probability of a malfunction or tear is high.
High-quality backpacks usually have ergonomic S-shaped shoulder straps that are designed to follow the contours of your body. They will usually feature thick foam padding so that the straps don’t cut into your upper body even if the backpack is heavy. Shoulder straps on good backpacks are covered with breathable mesh for ventilation, ensuring that you don’t get too sweaty while you are walking around with the backpack.
On the best backpacks, shoulder straps will usually have a few extra features. I’ll cover those in more detail a little bit later, but for now let’s say it’s not uncommon for shoulder straps to have attachment points for sunglasses and even tiny pockets.
Load Lifter/Stabilizer Straps
Load lifter straps are often seen in large-capacity backpacks designed for multi-day outdoor adventures. Their function is to let you adjust the position of a backpack harness so that it fits your body perfectly.
They’re also called stabilizer straps because adjusting the position of a backpack on your body helps stabilize its load. When a backpack is sitting on your torso in the optimal position, it’s much easier to carry it around even if it weighs more than 50 lbs.
Sternum Strap
Some backpacks have a sternum strap. It’s two pieces of webbing that lock with a buckle, and they’re supposed to connect the shoulder straps. A sternum strap helps keep the backpack more stable on your torso, ensuring that one of the straps doesn’t just randomly fall off your shoulder while you’re moving around.
Sternum straps can be fixed or adjustable. If a backpack has detachable sternum straps and several attachment points for them, you can adjust the position of the sternum strap to fit you perfectly. If you can’t remove the sternum strap, it means that it’s fixed.
A sternum strap is supposed to lie flat on your chest. Some outdoor backpacks feature sternum strap buckles that double as emergency whistles, allowing you to call for help in a pinch without having to use your hands.
Sternum straps are not mandatory backpack components. They’re unnecessary in small-capacity bags and everyday backpacks that you end up carrying on one shoulder anyway.
Hip Belt Strap
Hip belt straps are essential components of large-capacity backpacks. Their main purpose is to transfer a load of a backpack from your torso to your hips. By securing the backpack around your waist, the backpack load is stabilized and more evenly distributed across your body. You won’t be in pain even when you’re carrying a very heavy bag, and it’s unlikely you’ll be sore days later.
Hip belt straps are essential features of hiking, trekking, climbing, and some travel backpacks. In general, if a bag’s maximum capacity exceeds 40 liters, you will need a hip belt to stay comfortable when the pack is filled to capacity. Hip belt straps are not common in EDC and other small-capacity backpacks, and there are different types of hip belt straps.
It’s common for smaller backpacks to have hip belt straps that are just plain webbing. Their main purpose is to transfer the weight onto your hips and keep it there. Bigger and heavier backpacks will usually have more elaborate hip belts, with thick padding, breathable mesh, and even convenient pockets.
Compression Straps
Compression straps are common in large-capacity backpacks, especially the ones that are designed for outdoor activities. Hiking and climbing backpacks with multiple compartments often have several sets of compression straps, allowing the carrier to really adjust the bag to fit their body just right.
Compression straps are useful when you have a big backpack and you only pack half of it. Without the compression straps, the items inside the bag would jump around while you’re walking, often hitting you in the back and causing pain. The backpack would not be stable, and it would make you uncomfortable pretty fast. Compression straps let you stabilize the backpack load so that everything is nice and tight.
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Bungee Cords
Bungee cords are often found on sporty outdoor backpacks. They can hold bulky items that don’t fit inside the backpack, and they’re very useful for long outings that require you to carry all sorts of gear.
A backpack will usually have bungee cords instead of a stretchy front pocket. They both serve a similar purpose, but bungee cords are generally stretchier and more versatile.
Handles
All backpacks have grab handles, even those tiny leather ones that are only backpacks in the name. Most backpacks have a grab handle at the top, so you can easily pick up the bag with one hand.
Travel backpacks can have multiple grab handles depending on their design. It’s common for carry-on travel backpacks to have top and side grab handles, just like other luggage.
It’s worth noting that a grab handle can be anything, from a thin piece of webbing to a slash-proof chain.
Bonus Features
Frames, back panels, and compartments are indispensable backpack features – what about all those other things that you see on various different packs? That’s what we’re talking about in this section, so if you ever wondered what ice axe loops or MOLLE panels were, just keep reading!
Sleeping Pad Straps
A lot of outdoor backpacks are equipped with sleeping pad straps. These are usually just two stretchy loops at the bottom of the bag, on opposite sides. This is a convenient way of carrying sleeping pads since they don’t get in the way and take up no space inside your actual backpack.
LED Light Attachment Point
Most backpacks for cycling and mountain biking have an attachment point for an LED light. This helps people stay visible in the dark and it can save lives if you often ride your bike on dark roads. Although this feature is mostly for cyclists, it’s not uncommon to see it in everyday and hiking backpacks.
Helmet Attachment
Backpacks for mountain biking and cycling often have a dedicated attachment point for a helmet. This can be anything from a very stretchy pocket to a piece of plastic that you’re supposed to pull through your helmet.
Luggage Sleeve
Some backpacks have luggage sleeves, most often on the back panel. Luggage sleeves are meant to help you secure the backpack to the wheel handle of a suitcase so that it’s easier to move around with multiple pieces of luggage.
In some cases, luggage sleeves can double as extra pockets. If there are zippers on the top and bottom of a luggage sleeve, it’s so that you can transform it into an extra pocket when you’re not using the sleeve for travel.
Ice Axe Loops
Some hiking backpacks have dedicated ice axe loops. These are usually stretchy loops that are used to secure ice axes to the exterior of a backpack. They’re inconspicuous, and unless you specifically look for them, you’ll hardly ever notice them.
Trekking Pole Loops
Hiking and trekking backpacks usually have loops that let you secure hiking poles to the exterior of the bag. This is a very convenient feature for hikers since it frees up their hands.
Trekking pole loops are usually stretchy and are found in pairs.
MOLLE Panel
MOLLE panels are often found in military and rugged outdoor backpacks. A MOLLE panel is a system of external attachment points that allows you to secure bulky gear to the exterior of a backpack.
There are plain MOLLE panels and laser-cut MOLLE panels. Plain MOLLE panels are those that feature webbing loops arranged symmetrically. Laser-cut MOLLE panels are lighter and allow you to attach even more items to the exterior of a bag.
Daisy Chain
Daisy chains are often featured on hiking and backpacking bags. They are webbing loops sewn onto the backpack, and you can use a carabiner to attach anything you want to one of these loops. Daisy chain webbing can be located on the front, sides, back, and even shoulder straps of a backpack.
USB & Headphone Ports
Some everyday and laptop backpacks feature USB and headphone ports. A USB port connects to a power bank, so you can charge your phone through the backpack. It’s a convenient feature, especially if you’re always on your phone and need to charge it often.
Headphone ports are slowly becoming extinct just like headphone jacks. They’re tiny holes in the backpack that let you keep your phone in the bag and still listen to music with wired headphones. But it’s 2021 and we’re all using Bluetooth earphones anyway, so this feature is pretty much obsolete nowadays.
D-Rings
D-rings are metal/plastic loops that are found on some sporty backpacks. You’re supposed to use them to carry bulky gear that won’t fit inside the bag, so they serve a similar purpose like MOLLE panels and daisy chains.
The main difference is that those two are made with webbing and D-rings are metal/plastic. They are very sturdy and durable, so they’re great for carrying heavy and bulky items. However, they’re also quite heavy, which is why they’re not that common even in sporty backpacks.
About the Author Roger Timbrook
Roger is a little obsessed with travel. He has been to over 40 countries, broken 3 suitcases and owned over 10 backpacks in 12 months. What he doesn't know about travel, ain't worth knowing!
