Your Guide to Backpack Sizes and Buying the Right One

Backpacks exist in a variety of forms and sizes. That is why you must be clear about the type of bag you want when looking for the size that fits your needs best. 

If you are not sure about what backpack you should buy or invest in, read this article to have a better grasp of the different types of backpacks out there and their unique characteristics.

Everyday Backpack

The usual capacity of everyday backpacks ranges from 15 to 35 litres. However, it depends on the number of compartments and pockets on the outside. You can easily find one for you since everyday backpacks with different capacities are almost always available in stores. 

If you have been looking for a laptop backpack for your everyday work, you will see plenty of large ones available for you to buy. That’s because most manufacturers aim to make them this way and with various compartments and organiser panels to accommodate all of your smaller items.

Hiking Backpack 

In general, a day trek using a hiking backpack with a capacity of 30 to 35 litres should be sufficient. However, longer trails that involve using poles, ropes, and other gear may need a bag with a capacity of about 50 to 60 litres.

Hydration Backpack

With an average size of 7 to 10 litres, hydration backpacks are usually the smallest kind of backpack. Keep in mind that there are 3-litre hydration backpacks meant to hold the reservoir and a few other items. You can also find hydration packs with a capacity of 15 to 20 litres, although these are not as big as compact backpacks for typical trekking. 

Consider these qualities and necessary factors in choosing your hydration backpack: Where are you going? What will the trip be like? How long will you be in the wild? These are only a few questions that will help determine which type suits you.

Travel Backpack

There is even greater diversity when it comes to travel backpacks. The maximum capacity of a carry-on backpack is usually 40 litres, which is the same as a conventional carry-on suitcase.

These types are built to meet TSA carry-on requirements, and the bulk of them are oversized in every way. This should be at least 45 linear inches long, with the most frequent dimensions in 22" x 14" x 9".

However, all rules are disregarded when it comes to checked travel backpacks. If you need larger bags for long camping excursions or travel, you will notice that an average capacity is rare to find.

Considering a Backpack’s Capacity 

Feel free to browse Amazon reviews if you cannot find the actual size of the bag you are eyeing. Although you can often find the actual volume of the pack stated on the tags, this is not always the case, so take the initiative to ask.

You can even try estimating the size on your own, but this can be tricky. The chances are that you will get rather accurate findings if you look at a rectangle or square bag and a higher figure if you are measuring an oval-shaped one. 

Keep in mind, though, that you are simply calculating the capacity of the main compartment, so you may not be taking into account the various extra pockets that a bag may have.


There you have it, a quick size guide to the different types of backpacks. When buying your pack, do not hesitate to ask store personnel, as sizes can also vary according to their brand. 

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