Backpacks are probably one of those things that many people don’t bother measuring. However, getting the wrong size backpack, as well as several other factors, may lead to neck and shoulder pain. For that reason, it’s generally a good idea to choose a backpack size that matches your size and needs.
The standard everyday backpack typically measures 22 × 14 × 9 inches (55.9 × 35.6 × 22.9 centimeters), give or take a few inches. They are designed to carry around 15 to 35 liters (4 to 9.2 gallons) of supplies at a time. However, the actual dimensions of a backpack will typically depend on what kind of backpack it is and how much stuff it can store at once.
For the remainder of this guide, I will briefly cover the various kinds of backpacks, their size dimensions, and other factors that you should consider when shopping for a backpack.
Backpack Types Based on Uses and Carrying Capacity
There are 2 ways we can categorize backpacks—by their uses and by their carrying capacities. I’ll cover both categorizing methods below.
Backpacks by Uses
When categorizing backpacks by how they’re intended to be used, they generally fall into one of 3 categories: hydration, everyday, and hiking.
Hydration backpacks are the smallest type of outdoor bag that is immediately identifiable by a pouch or bladder used to store liquids. Some of the smaller hydration backpacks are designed to carry as little as 7 liters (1.8 gallons) of supplies at once, while larger ones have more than double the carrying capacity (20 liters or about 3.6 gallons). Before being filled with liquid, a small-sized hydration backpack will measure around 11 × 10 × 4 inches (27.9 × 25.4 × 10.2 centimeters).
Everyday backpacks are backpacks that you can use for anything, including hiking and storing school supplies. They typically hold between 15 to 35 liters (4 to 9.2 gallons) of supplies at a time, and they have soft cushioning and internal pockets to store large laptops, textbooks, and stationery. The average size of a standard everyday backpack will typically measure 22 × 14 × 9 inches (55.9 × 35.6 × 22.9 centimeters).
Hiking backpacks are made for those that need to carry large supplies during outdoor excursions. They generally have waterproof exteriors, which will keep your supplies dry at all times. Hiking backpacks range from 20 to 60 liters (5.3 to 15.9 gallons) of supplies at once, though some hiking bags can be even larger. Depending on the capacity of the hiking bag, it can be as small as 17 × 8 × 5 inches (43.2 × 20.3 × 12.7 centimeters) or as large as 30 × 18.5 × 12.5 inches (76.2 × 47 × 31.8 centimeters) when empty.
Backpacks by Capacity
When looking exclusively at backpacks for outdoor activities, you will generally want to know how much they can carry at once. For that reason, we can categorize backpacks by their carrying capacities. The 3 main categories are weekend, multiday, and extended-trip backpacks.
Weekend backpacks are highly efficient, ultra-lightweight bags that can be used for carrying supplies for up to 3 nights. They generally hold up between 30 and 50 liters (7.9 and 13.2 gallons). Many 40-liter weekend backpacks measure 21 × 11 × 8 inches (53.3 × 27.9 × 20.3 centimeters).
Multiday backpacks are bags large-sized outdoor bags that carry between 50 and 80 liters (13.2 and 21.1 gallons) of supplies at any given time. These backpacks are ideal for outdoor trips lasting between 3 and 5 nights. If you shop for a 65-liter backpack, it’ll measure around 27 × 16 × 9 inches (68.6 × 40.6 × 22.9 centimeters).
Extended-trip backpacks are oversized backpacks that can carry as many supplies as you need for a trip that lasts over 5 nights. They can carry as little as 70 liters (18.5 gallons) of clothing and cooking utensils, but some bags go over the 100-liter (26.4 gallons) figure. They will contain various compartments on the sides and near the bottom of the bag, but on average, a 100-liter bag will measure somewhere around 18 × 13 × 9 inches (45.7 × 33 × 22.9 centimeters).
Bag Size Chart
You can use the following table as a reference for knowing backpack sizes based on their types.
|Backpack Types||Dimensions (H × W × D)||Capacity|
|By Uses||Hydration||11 × 10 × 4 inches
27.9 × 25.4 × 10.2 centimeters
|Everyday||17 × 8 × 5 inches
43.2 × 20.3 × 12.7 centimeters
|15 to 35 liters
4 to 9.2 gallons
|Hiking||30 × 18.5 × 12.5 inches
76.2 × 47 × 31.8 centimeters
|20 to 60 liters
5.3 to 15.9 gallons
|By Capacity||Weekend||21 × 11 × 8 inches
53.3 × 27.9 × 20.3 centimeters
|30 and 50 liters
7.9 and 13.2 gallons
|Multiday||27 × 16 × 9 inches
68.6 × 40.6 × 22.9 centimeters
|50 and 80 liters
13.2 and 21.1 gallons
|Extended-Trip||18 × 13 × 9 inches
45.7 × 33 × 22.9 centimeters
|70 to over 100 liters
18.5 to over 26.4 gallons
Available Features in Backpacks
When shopping for a backpack, you will come across a wide assortment of features. I’ll go over some of the more important ones down below.
A backpack’s frame refers to the solid panels built into or around a backpack to give it structure. There are 3 types of frames to choose from—internal, external, and frameless. Frameless backpacks may come with detachable frames to increase storage capacity and reduce weight.
Ventilation refers to how much air can pass through a backpack. A poorly ventilated backpack may induce back sweat, which can make hiking intolerably uncomfortable. Some backpacks have built-in “chimneys” that force air toward your back to solve ventilation problems.
A backpack’s pockets refer to the small compartments that are stitched onto the sides or near the bottom of the backpack’s base. The more pockets there are, the more small-sized items you can keep separate from large-sized camping supplies.
Compartments are individual storage spaces in and around backpacks with zippers. They are used mainly for organizational purposes.
The thicker the padding, the less prone delicate electronics, such as laptops or smartphones, will become damaged when placing your backpack on the ground. You should also look at the padding on the straps to ensure that they don’t dig too deep into your shoulders when the backpack is full.