The right hiking backpack size depends mainly on the duration of your tour. For half-day hikes, 10–15 litres is enough, for day hikes 20–30 litres is ideal, and for hut-to-hut tours with one overnight stay, 25–35 litres. Multi-day trekking tours with your own tent and sleeping bag require 50 litres or more. On top of that comes individual fit: it's not your body height but your torso length that determines which backpack size truly fits.
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Backpack Size by Tour Duration: The Overview
The size of a hiking backpack is stated in litres and describes the maximum capacity. Basic rule: as big as necessary, as small as possible. A backpack that's too large tempts you to pack more – and every extra kilo makes itself felt on long tours.
| Volume | Tour type | Typical contents |
|---|---|---|
| 10–15 litres | Half-day or urban hike | Water bottle, snack, light jacket |
| 20–30 litres | Easy day hike | Food for one day, rain jacket, first-aid kit |
| 25–35 litres | Challenging day hike / 1 hut overnight | Helmet (via ferrata), change of clothes, hut sleeping bag liner |
| 30–45 litres | Hut tour, 2–4 nights | Change of clothes, hut sleeping bag liner, toiletries, cooking set |
| 50–60 litres | Trekking with lodging, 1 week+ | Complete gear, no tent of your own |
| 60–85 litres | Trekking with tent / winter tours | Tent, sleeping bag, sleeping mat, cookware, food |
What Does "Litres" Mean for a Hiking Backpack?
The litre rating describes the interior volume of the main compartment plus all additional pockets. So a 30-litre backpack holds 30 litres of content – roughly equivalent to a medium-sized carry-on suitcase. What matters isn't just the volume, but also the layout: separate compartments for a rain cover, hydration system, or sleeping mat significantly increase practical usability.
A backpack chosen on the tighter side is the simplest weight brake there is. Volume should be chosen based on realistic needs – not according to the motto "better to have some extra room."
Measuring Torso Length: How to Find the Right Fit
Many hikers choose their backpack by volume – and still end up buying the wrong one. The most common mistake: fit gets ignored. For trekking backpacks from around 30 litres upward, torso length is crucial, because the carrying system transfers the weight onto the hip belt. If the backpack sits too high, the load ends up on the shoulders. If it sits too low, it chafes against the buttocks.
Measuring Torso Length – Step by Step
- Tilt your head slightly forward. The 7th cervical vertebra is the vertebra that protrudes most at the neck – that's the upper measuring point.
- Stand up straight and place your hands on your hips. Your thumbs point to the iliac crest – that's the lower measuring point.
- Measure the distance between both points with a tape measure. It helps to have a second person assist.
- Compare your result with the size chart of the respective manufacturer. The figures vary by brand.
Torso Length: Rough Guide by Body Height
Torso length can't be directly derived from body height – two people of the same height can have very different torso lengths. Still, as a rough guide:
| Torso length | Backpack size (fit) | Common label |
|---|---|---|
| up to approx. 44 cm | XS / S | Short / Small |
| 44–49 cm | M | Medium / Regular |
| from 49 cm | L / XL | Large / Tall |
Note for Women: SL Models
Many manufacturers such as Deuter or Osprey offer their hiking backpacks in special women's versions. These so-called SL models (Slim Line) have a shorter carrying system, narrower shoulder straps, and a differently shaped hip belt adapted to female body symmetry. Women are generally advised to try an SL model, even if torso length alone would technically fit a unisex model.
How Heavy Should a Hiking Backpack Be?
Volume alone says little about actual weight. What matters is how much you pack. As a general rule of thumb: on a day hike, the total weight of the loaded backpack should not exceed 10% of your body weight, and on multi-day tours, a maximum of 20%. At 70 kg body weight, that would be 7 kg for the day hike and 14 kg for the multi-day tour.
Important: the backpack's own weight is included in the total weight – for quality trekking backpacks, that's between 1.2 and 2.5 kg. Anyone with a higher body weight or who is less trained should apply the limits more conservatively: 8% and 15% respectively are then the more realistic guide values.
Checklist: What to Look For When Buying
- Choose volume to match the tour – day hike: 20–30 L, hut tour: 30–45 L, trekking: 50 L+
- Measure torso length – before buying, don't just estimate
- Check hip belt length – the hip belt must rest on the iliac crest, not on the waist
- Test the carrying system – if possible, try on the loaded backpack in the shop
- Women: consider an SL model – adapted shoulder straps and hip belt
- Note the backpack's own weight – lighter models from around 1 kg, standard models 1.5–2.5 kg
- Choose back ventilation based on use – mesh back for hot tours, contact back for more stability with heavy loads
FAQ: Frequently Asked Questions About Hiking Backpacks
What backpack size do I need for a day hike?
For easy day hikes on well-marked trails, 20–30 litres is sufficient. That fits food for one day, a rain jacket, a water bottle, and a first-aid kit. For more challenging tours or via ferratas, 25–35 litres is recommended to accommodate extra gear like a helmet or via ferrata set.
How many litres do I need for a hut tour with an overnight stay?
For a weekend tour with one hut overnight stay, 25–35 litres is sufficient. For multi-day hut tours with two to four nights, 30–45 litres is recommended. Anyone carrying their own tent, sleeping bag, and cooking gear should plan for at least 50 litres.
How do I measure my torso length for a backpack?
Torso length is measured from the 7th cervical vertebra (the most prominent vertebra at the neck when the head is tilted forward) to the top edge of the iliac crest. A tape measure is enough, and a second person helps. The result in centimetres is then compared against the size chart of the respective manufacturer.
How heavy can a hiking backpack be at most?
As a rule of thumb: a maximum of 10% of body weight for day hikes, and a maximum of 20% for multi-day tours. At 70 kg body weight, that's 7 kg or 14 kg respectively. The backpack's own weight (approx. 1–2.5 kg) is already included in that. Less trained hikers should apply the limits more conservatively.
What's the difference between a hiking backpack and a trekking backpack?
A hiking backpack (10–45 L) is designed for day trips and short multi-day tours, often with a simple carrying system. A trekking backpack (45 L and up) is built for longer tours and features a sophisticated carrying system with adjustable torso length, a padded hip belt, and weight distribution across the hips.
Do women need a special hiking backpack?
Not strictly necessary, but recommended. So-called SL models (Slim Line) are specially adapted to female anatomy: a shorter carrying system, narrower shoulder straps, and a differently shaped hip belt. Manufacturers such as Deuter or Osprey offer their models in women's versions.