Choosing a hiking rucksack isn't about picking the biggest or the cheapest: it's about finding the one that suits YOUR outings. A rucksack that's too small forces you to leave out the essentials; one that's too big just means you're carrying dead weight all day for nothing. Between capacity in litres, carrying comfort and rain resistance, a few simple guidelines are all you need to get it right.
To cut to the chase: go for 20 to 30 litres for a day out, 30 to 40 litres for a demanding hike or a weekend away, and 50 litres or more for a self-sufficient trip with a tent and sleeping bag. We'll break it all down — capacity, carrying comfort, waterproofing — but first, here are three rucksacks we recommend, one for each use.
Our selection
Three rucksacks that cover the essentials of hiking: the compact one for day trips, the versatile 40-litre that goes anywhere, and the large-capacity one for self-sufficient treks. You can also browse our full collection of hiking rucksacks to compare capacities.
Which capacity to choose for your hike
This is the first question to ask yourself, even before brand or colour. A rucksack's capacity is measured in litres, and it should match the length of your outings rather than a desire for "extra room just in case". Here are the main categories:
- 20 to 30 litres — day hiking. Enough room for water, a windbreaker, a picnic and a first aid kit. Lightweight and close to the back, ideal for a day out on the trail.
- 30 to 40 litres — the versatile size. The best all-rounder for most hikers: a long, well-packed day, a light spot of wild camping or a weekend in a mountain hut all fit in easily.
- 40 to 50 litres — light trekking. Once you start sleeping outdoors but share the gear load (a two-person tent, a shared stove), this volume is enough for two to four days.
- 50 to 70 litres and above — full self-sufficiency. Tent, sleeping bag, stove, supplies for several days: it all goes on your back. Save this volume for proper treks, otherwise you'll end up filling it "because there's room".
To see at a glance which volume suits how you hike, here's the summary:
| Capacity | Type of outing | Self-sufficiency | Who it's for |
|---|---|---|---|
| 20 – 30 L | Day hikes | A few hours to 1 day | Short walks, light outings, trail running |
| 30 – 40 L | Challenging hikes, weekend trips | 1 to 2 days | The most versatile size |
| 40 – 50 L | Light trekking, nights in mountain huts | 2 to 4 days | Hikers sleeping outdoors without carrying absolutely everything |
| 50 – 70 L and above | Self-sufficient trekking, wild camping | 4 days and more | Tent, sleeping bag, stove: everything on your back |
The criteria that really matter
At equal capacity, it's the carrying system and finish that separate a good rucksack from one you'll regret after two hours of walking. Five points to check:
- The carrying system. A good rucksack shifts the weight onto your hips, not your shoulders. A padded hip belt and adjustable shoulder straps make all the difference once the rucksack is loaded up.
- Ventilated back panel. A mesh back panel or one with ventilation channels limits sweating — invaluable on climbs and in warm weather.
- Adjustments. Load-lifter straps, chest strap, adjustable back length: this is what keeps the rucksack snug against your body and stops it swinging with every step.
- Access and organisation. Top opening, front access, integrated water bladder pocket, walking pole attachments: these save you loads of time so you're not emptying the whole bag just to grab your fleece.
- Durability. Abrasion-resistant fabric, reinforced seams, sturdy fastenings: a hiking rucksack rubs against rocks, drags along the ground and lives outdoors.
- The frame and support. On larger volumes, a frame (a rod or plate in the back panel) transfers the load onto your hips and keeps the rucksack stable. Small day packs don't need one, but from 40-50 litres upwards, it makes all the difference to comfort.
- The empty weight. For the same capacity, every hundred grams less makes a difference after several hours of walking. Check the weight of the rucksack when empty before you pack it: it's comfort gained for the whole outing.
Waterproofing: don't underestimate the rain
No rucksack fabric is ever fully waterproof at the seams and zips: during a prolonged downpour, water always finds its way in where you least expect it. There are two ways to keep your gear dry. The first is a rain cover that slips over the rucksack, often supplied with larger models and tucked away in its own pocket. The second is a rucksack built with a waterproof design, made for wet climates, mountain conditions or outings near water. If your hikes often mean rain, mist or river crossings, it's better to go straight for a model designed with water in mind rather than relying on a cover that's easily forgotten at the bottom of your bag.
30L Waterproof Hiking Rucksack
£76.90
Pay in 4 instalments of £19.23 interest-free with Shop Pay
Men's, women's, kids': what's the difference?
The volume and carrying features stay the same, but your body shape affects comfort. Women's rucksacks have a shorter back length, pre-shaped shoulder straps and a hip belt designed for a woman's hips. Kids' models focus on lightness and adjustments that grow with your child. What matters isn't the label but your back length: a rucksack properly adjusted to the right back length will always feel better than a poorly fitted "unisex" model. Before buying, measure your back length (from the base of your neck to the small of your back) and trust this measurement more than the gender shown on the label.
Staying hydrated for the long haul
On a long outing, stopping to get your water bottle out of your rucksack becomes less and less appealing — so you end up drinking less than you should, which soon takes a toll on your energy and alertness. A water bladder slipped into its dedicated compartment, with the tube within easy reach of your mouth, lets you take small sips without stopping or putting your rucksack down. Most of our hiking rucksacks have a channel designed for the tube: a real comfort when the miles add up and every pause costs you momentum.
£33.90
Pay in 4 instalments of £8.47 with no fees via Shop Pay
Adjusting your rucksack properly before you set off
Even a perfect rucksack feels uncomfortable if it's not adjusted properly. The method comes down to four steps, in order: loosen all the straps, load the rucksack (heavy items close to your back and high up), tighten the hip belt first so it sits on your hips, then adjust the shoulder straps, and finally the load stabiliser straps. All that's left is knowing what to pack: our hiking rucksack checklist covers the essentials to bring along. To help you plan your outings and progress safely, the French Hiking Federation publishes plenty of practical advice.
Frequently Asked Questions
What size rucksack do I need for a day hike? A volume of 20 to 30 litres is enough: water, snacks, windproof jacket, first aid kit and a few bits and bobs. Beyond that, you'll just be carrying empty space.
What capacity do I need for a multi-day trek? Allow 50 to 70 litres if you're self-sufficient with a tent, sleeping bag and stove. If you're staying in mountain huts or sharing gear, 40 to 50 litres may be enough.
How do I know if a rucksack is the right size for me? It's your back length that matters, not your clothing size. A well-fitted rucksack sits on the hips, with the hip belt carrying most of the weight; the shoulder straps are just there to stabilise it.
Is a hiking rucksack waterproof? Rarely 100%: the seams and zips let water through. Use a rain cover, or choose a model designed to be waterproof if you often walk in the rain or near water.
