There are many factors to consider when choosing a tactical backpack, depending on the intended use. For a novice hiker, you are unlikely to need a top-of-the-range bag which will set you back hundreds of pounds.
The most important aspects to consider are the size, material, access points, and the weight distribution features the bag includes. The bag you choose should be comfortable enough to wear for extended periods of time, and functional enough to make your life easier.

Tactical backpacks can range in price from around $30 for basic models to $200 for a more professional and durable product. Assess the functionality, your personal needs, and the cost per use when deciding how much to spend on your backpack.
Choosing A Tactical Backpack
How big does it need to be?
This tends to be measured in cubic inches, calculated using the width and height. It is easier to reframe this to think of the volume in liters. Sizes of backpacks tend to range from around 5 to 60 liters.
EDC (everyday carry) bags tend to be in the range of 5-35 liters and are usually only used for around 12 hours of supplies. 24-hour packs are from 30-40 liters. 3-day packs are the largest, at 40-65+ liters.
The size of backpack you will require depends on the duration of your expedition and the number of supplies you need to carry.
What is it made from?
The most common materials for tactical backpacks are polyester, ripstop, Cordura, and ballistic nylon.
Ballistic nylon is designed to withstand shrapnel fragments and is a very durable material. It was used in WWII to make jackets for airmen!
Cordura is another durable material with a resistance to tears and scuffs. It is commonly used by the US military and is a good option for backpack material.
Ripstop is a tear-resistant material. It is less durable than ballistic nylon and Cordura but is still very tough.
Polyester is the least durable material, but probably the most lightweight and comfortable to carry.
Straps
As you will be carrying this backpack for an extended period of time, load management is absolutely vital. Poor load management will cause you to tire much faster and can even lead to injuries being sustained.
The first thing that you should consider is the shoulder straps. There are 3 main designs: straight, curved, and one-piece. Curved are the most common as they have the most ergonomic design. They are full of padding and easily adjustable.
Straight are the least common as they are designed to look better instead of fitting better. They are often loose than curved straps meaning there is a lot of space to fit padding in. One-piece straps are the most durable and are attached via one piece of material behind the shoulder blades.
For larger and heavier backpacks, consider choosing one with a sternum strap. This attaches across the top of your chest and ensures the weight of the backpack is more evenly distributed. It provides extra stability and balance as the backpack cannot swing, which is ideal for uneven terrain.
Hip belts are another great way to improve the load management of your backpack. This is not necessarily on smaller bags but will make a huge difference if you are carrying a heavy load.
These belts shift some of the weight from your shoulders and back to your hips, making it easier to carry. It makes use of your core strength to manage the weight distribution.
Frame
A frame will add an element of rigidity to your backpack, making the weight distribution more even. Your backpack can contain a frame sheet. This is a flat sheet of plastic installed in the back panel and will ensure the backpack retains its shape.
Internal frames are constructed from stays (aluminum rods). They are attached to the hip belt and transfer the weight from your shoulders to your hips.
The other type is an external frame and is the oldest of the frames. They have declined in popularity recently but they have some advantages still. For instance, an external frame allows you to attach extra equipment directly to the frame.
Access and opening mechanism
There are 7 different ways tactical backpacks are designed to open. These are side access, rolltop, front access, Y-access, top access, clamshell, and splayed.
Side access have zippers along the edges of the backpack for quick access to your belongings. Rolltop bags have a top flap that rolls up and is secured with a buckle. These tend to be very waterproof.
Front access bags open like a door and are very useful for organization. They have many different compartments to store your equipment in for easy access. Top access bags have a zipped pocket at the top to access your belongings in a vertical manner. They ensure your gear will not fall out accidentally.
Y-access bags open almost completely for quick access to all of the contents of your bag. This is very popular with more experienced hikers due to the increased accessibility.
Clamshell bags open much like a traditional backpack, essentially with a hinged panel on the front. Splayed bags have multiple compartments separated by fabric, and are perfect for easy organization.
Pockets
At their most basic, tactical backpacks will have a main and secondary compartment - the two biggest pockets of your bag. They may come with CCW pockets to carry a gun, or a laptop sleeve if that is more your speed.
They typically include additional pockets made of mesh for carrying bottles and glasses. There may even be pockets specially designed to hold pens, documents, or even velcro fields to attach identification documents.
Does it come with any additional extras?
There are a number of added features you can find in tactical backpacks. By far the most useful is a hydration bladder.
This allows you to carry around a supply of fresh water and drink it while on the move, without having to stop to retrieve a bottle from your bag.