Why Shall I Use a 40L Backpack?

  • by Ramin Golzari
Why Shall I Use a 40L Backpack?

Even we’ll admit it, the wide world of backpacks can get a bit confusing. You just want a nice bag that fits all your gear and doesn't wear you out before you make the peak. But there’s the problem – carrying lots of heavy gear and being comfortable is a contradiction. A bag must be pretty canny to do both well. A 40L backpack sits in the sweet spot between lightweight daysacks and heavy-duty 80L rucksacks. They’re extremely flexible – working for average day hikes and overnight wilderness camping. They also give you the extra room needed for climbing gear or winter hikes.


What is the difference between a backpack & a rucksack?

In some countries, rucksack refers to a bag that’s a bit larger than a backpack, or one specifically designed for travelling. However, the words backpack and rucksack are used interchangeably in the UK – and you’ll definitely spot us doing the same!

Why are backpacks measured in litres?

Backpacks can come in all shapes and sizes, so it can be hard to compare them based on measurements. Instead, we measure the capacity of the bag in litres. Manufacturers will actually fill a bag with water to calculate this! They have to fill each pocket as well, as the total volume of the bag normally includes every pocket as well as the main compartment.

How to properly fit your backpack

Step 1: Measure your body before you buy a backpack
The most important measurement is your back length (from your hip to your most prominent neck vertebrae). This helps you choose the right bag size or fit an adjustable back system correctly.

Step 2: Fill your bag
Add items to simulate the weight of your hiking gear. Make sure they are evenly distributed inside, or you’ll adjust it too far in one direction for comfort.

Step 3: Adjust the hip belt first
Start by finding the right position on your hips for your hip belt or strap. 80% of your pack weight should rest on your hips, so you might have to pull it higher or tighter than you’re used to.

Step 4: Adjust the shoulder straps and back
Tighten the shoulder straps as necessary. The ideal fit leaves no gaps between the strap and your neck, but shouldn’t dig in at all. If they’re not sitting flat, you can look at adjusting the back length.

Step 5: Check the last straps for small adjustments
It’s easy to forget about your chest strap and load-lifters, but they have important jobs. Your load-lift straps sit on top of your shoulder straps and should be pulled to a 45˚ angle. Your chest strap sits just under your collarbone and, adjusted properly, should take a wee bit of pressure off your shoulder straps, and give your arms more movement.


What is a 40L backpack good for?

A 40L backpack is your perfect weekend companion. With clever storage, you’ll have plenty of room for a sleeping bag, solo tent, camping mat, food, and extra clothing and layers to keep you comfy.
You can take 40-45L backpacks as carry-on for flights. Most airlines allow carry-on luggage that measures up to 22” x 14” x 9”. This should accommodate most 40-45L bags, as long as they’re not too structured. Anything bigger, and you might have to get it checked in.

How to pack a 40L backpack?

The most important thing to remember when packing your 40L bag is to keep the weight evenly distributed. Ideally, you keep your heaviest kit in the middle section of the bag, spread between left and right sides. You don’t want all the heaviest items sitting at the bottom, as that puts more strain than needed. Then you’ll want the top of your pack reserved for quick-grab items like jackets and scran. If you’re struggling, check out our guide to organising large rucksacks for tips.



How much weight is it ok to carry on my back?

You should never carry more than 20% of your bodyweight on your back. For an average person weighing about 80kg, that means you shouldn’t carry more than 16kg.

Truth be told, the less weight you can carry, the happier you’ll be on the hill. 10kg is a great aim for beginner hikers.

How do you use a gear loop on a backpack?

Backpack gear loops give you more options for storing items. You might like to use them for bulky items like your camping mat, so it doesn’t take up valuable rucksack space. Or you might store an insulated or waterproof jacket that you need to reach at short notice.
They’re probably most often used for ice axes or walking poles that don’t have an easy spot to store inside the bag.


And now, armed with everything you wanted to know about 40L backpacks, you’re ready to make your choice and get out into the wilds. Did you find your perfect hillside companion from our list? We’d love to see it. Tag us in your pictures for a share on socials.


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