Use the following guide to help you decide what size rucksack you will need;
10 - 25 litres - only if you want to travel light or cover ground quickly
25 - 35 litres - ideal for shorter day walks
34 - 45 litres - good for hill and mountain walking
45 - 55 litres - use when mountaineering or lightweight camping
55 - 75 litres - for camping expeditions and long distance hikes
75+ litres - for reaching and camping in remote locations.
Some features to look out for:
Shoulder straps/harness - These shouldn’t be the main weight bearers of the rucksack but should help keep the pack close to the body and centred. Easily adjustable, well padded straps will help you maintain a proper fit which will prevent rubbing and allow full freedom of movement.
A chest strap - Helps further control the alignment of the shoulder straps.
Hip belt – The hip belt helps transfer some of the weight from the shoulders to the hips. It needs to be adjustable (fastening above the hips), well padded and comfortable.
Waterproof cover – No rucksack will be fully waterproof regardless of its construction materials. There are too many seams and fastenings to be able to keep the contents completely dry. Some rucksacks will have a built in rain cover, for others you can buy them separately.
Some rucksacks provide ventilation by pushing the pack away from your back and reducing the areas of contact to just the waist and shoulders.
As with boots, it’s a good idea to try before you buy to make sure the fit and feel is right for you.