Walk into any outdoor shop and there is a wall of rucksacks, all of them looking much the same and none of them telling you which one is for you.
Here is the short version. For UK day walks in the hills, you want 30 to 40 litres. Buy the size that matches the trips you actually do, then spend your time getting the fit right rather than comparing brands. A cheap bag that fits you properly will be more comfortable all day than an expensive one that does not.
Below we will go through the three things that actually matter when you are buying: getting the size right, getting the fit right, and which features are worth paying for.
What should you know before buying a rucksack in the UK?
Four things, in this order of importance.
- Size, in litres. Match it to your longest realistic trip. For most UK hill walkers that is 30 to 40 litres.
- Back length. Rucksacks are sized to your torso, not your height. Getting this wrong is why bags hurt.
- A proper padded hip belt. This is what carries the weight. A bag without one is a day-sack, whatever the label says.
- Whether it fits when loaded. Fill it in the shop. An empty pack tells you nothing about how it will sit with 8 kg in it.
Everything else, the fabric, the colour, the number of pockets, the brand, is a long way down the list. UK weather means you will also want a rain cover or a liner, but that is a five pound problem, not a buying decision.
What size rucksack do I need?
Bag size is measured in litres, and it tells you how much you can fit inside. Ideally you want a bag big enough to fit everything in easily, without strapping things to the outside.
Kit hanging off the outside gets damaged, gets lost, and swings around as you walk, which makes the whole day harder than it needs to be.
| Capacity | What it is for | What goes in it |
|---|---|---|
| 20–30 L | Short summer day walk | Waterproof, extra layer, food, water, map and compass |
| 30–40 L | Long or winter day walk | All of the above plus warm kit, spare gloves, flask, head torch |
| 45–55 L | Multi-day, huts or hostels | Several days of clothing and food, no tent or stove needed |
| 55–65 L+ | Multi-day, camping | Tent, sleeping bag, mat, stove and fuel on top of everything else |
Watch how the litres are counted. A 50-litre bag could be a 30-litre main compartment with 20 litres of pockets, which may be less useful to you than a 45-litre bag with a 5-litre pocket. Check the size of the main compartment, not just the headline number.
Most people end up with two different sizes for different trips. If you are buying one bag, think about what you will use it for most often and buy for that.
How do you fit a rucksack properly?
This is the part that gets skipped, and it makes more difference to your day than anything on the spec sheet. It matters less on a small bag for a short trip, but as soon as you are carrying real weight for a full day it is the difference between comfortable and miserable.
Fill the bag first. An empty pack fits nothing like a loaded one, so put some weight in it before you start adjusting, in the shop as well as at home.
- Set the back length. Any decent large rucksack either comes in different sizes or has an adjustable back. Measure your torso, not your height, and set the bag to match.
- Hip belt first. Your legs are the strongest part of your body, so we want the weight going through your hips and down your legs rather than hanging off your back. Sit the belt just above your hip bones and tighten it. This should take most of the weight off your shoulders straight away.
- Shoulder straps next. Snug, not tight. They hold the bag against you, they do not hold it up. Overtightening puts pressure on your shoulders and chest for no benefit.
- Load lifters. The two short straps running from the top of the bag to the shoulder straps. Pull these in so the top of the pack comes towards you. Without them the bag drags you backwards and you end up leaning forward all day to compensate.
- Chest strap. Comfortable, never tight. Its job is to stop the shoulder straps sliding outwards, nothing more.
- Compression straps. Finally, pull these in to squeeze the load small and close to your back so it stops swinging around.
That is it. Do that once properly and you will notice the difference immediately.
If your shoulders ache at the end of a day, the hip belt is almost always the problem. Most people tighten the shoulder straps to take the weight, which is exactly backwards.
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What features are worth looking for?
There is a whole host of features on bags that you may or may not want. Here are the ones worth understanding before you buy.
- Padded hip belt. Not optional on anything over about 30 litres. This is the single most important feature on the bag.
- Adjustable back length. Lets you tune the fit rather than hoping the one size works.
- Compression straps. Pull a part-full bag in tight so the load stops moving.
- Hydration compatible. A sleeve for a water bladder and a port for the tube. Handy, though a bottle in a side pocket works fine and is easier to refill.
- External pockets. Useful for the things you want without stopping, like suncream and snacks, and for keeping fuel separate from everything else.
- Walking pole loops. Somewhere to stow poles when you are scrambling or when you want your hands free.
- Rain cover. Worth having, but never rely on it alone. Line the bag with a dry bag or a bin liner as well.
That last point matters more than people expect. There is a full rundown in how to keep your stuff dry in a rucksack, because a soaked sleeping bag ends a trip.
What to do next
Once you have the bag, the next question is what goes in it. Our kit list for a day on the hill covers exactly that, and the layering system explains what you should be wearing and what should be in the bag as a spare.
Here is your practice. Load your bag with what you would actually carry, put it on in the kitchen, and work through the six steps above. Then walk around the house for five minutes. You will find things to adjust, and you would much rather find them there than two hours into a walk.
Free course: once the bag is sorted, the rest of the planning is what keeps you safe. My free Digital Safety Net course walks you through planning a walk from start to finish, including kit, weather and route choice.
Any questions, please ask below.
What size rucksack do I need for hiking in the UK?
For most UK day walks in the hills, 30 to 40 litres is the right size. It carries a waterproof, a warm layer, food, water, map and compass, plus the extra kit a winter or longer day needs. A 20 to 30 litre bag is enough for a short summer walk, and you only need 55 litres or more if you are camping and carrying a tent and stove.
How do I know what back length rucksack to buy?
Rucksacks are sized to your torso length, not your height, so a tall person with a short back needs a different size to what you would guess. Measure from the bony bump at the base of your neck down to the top of your hip bones. Most decent large packs either come in two or three back sizes or have an adjustable back panel you can set yourself.
Do I really need a hip belt on a rucksack?
On anything over about 30 litres, yes. The hip belt transfers the weight onto your hips and down through your legs, which are far stronger than your shoulders and back. A bag without a proper padded hip belt will put all of the load on your shoulders, and you will feel it after a couple of hours.
Why do my shoulders hurt when I wear my rucksack?
Almost always because the hip belt is too loose or sitting in the wrong place, so your shoulders are carrying weight they should not be. Load the bag, sit the hip belt just above your hip bones and tighten it first, then loosen the shoulder straps and re-snug them. The straps hold the bag against you, they do not hold it up.
What does litres mean on a rucksack?
Litres measure the volume the bag holds. It is worth checking how that total is made up, though, because a 50-litre bag might be a 30-litre main compartment plus 20 litres of pockets. That can be less useful than a 45-litre bag with one big compartment, so look at the main compartment size rather than the number on the label.
Is an expensive rucksack worth it?
Fit matters far more than price. A cheaper bag that is the right back length and has a proper padded hip belt will be more comfortable all day than an expensive one that does not fit you. Where money does buy something real is durability, better harness padding and a genuinely adjustable back, which is worth having if you are carrying heavy loads regularly.
