You want something able to carry all your kit, and be comfortable. There's a wide range out there, so before you hit the shops we wanted to highlight the important features you should be aware of when making a choice.

How big should it be? For a day walk in the UK you want a bag around 30 litres. Much bigger than this and the bag will be a big saggy mass with your kit at the bottom; this not only looks silly, it's more likely to blow around in the wind and be annoying. Too small and, obviously, you won't get your kit inside. For a full day kit list you can see our advice HERE.

Aside from the number of litres, bags are made for different sizes of people. They are normally just small, medium or large, but as these can make quite a bit of difference to comfort, make sure you know what size you are. Staff in Cotswold Outdoor do bag fittings, and most outdoor shop staff should be able to help. At the very least, try on all the sizes yourself.

Look at the waist strap

For walking, you definitely want a bag with a thick waist strap. This strap should be done up firmly so that your hips take most of the weight of the bag, a much more comfortable way of walking than if all the weight is on your shoulders. Some waist straps also have pockets attached, so think about whether you want these.

Look at the shoulder straps

These straps hold the bag against your back and stop it moving around. As thin straps can often bite into your shoulders after a day out, consider whether you want padding; thicker straps generally dig in less than thin ones. The adjustment of shoulder straps should be easy while walking.

The shoulder straps are connected by a breast strap which passes across your upper body over your chest. This makes carrying a bag more comfortable as it helps transfer the weight from your shoulders to the chest and prevents the shoulder straps from slipping off. Ideally look for a breast strap that can be moved up and down, which makes for finer adjustment.

Want extra pockets?

Besides the large inner space of the bag, many will have extra pockets on the outsides, where you can put kit for easy access. Frequently there will be pockets on the sides where a water bottle can go, and one in the lid. There may also be a big pocket on the back, outside the main bag, where a waterproof or hat and gloves can be stashed. And you may even get pockets on the shoulder straps and waist strap. All these additions are good for easy access items such as snacks or a woolly hat, so think about what you'd like to be able to grab while walking without taking the bag off.

Author: Alex Kendall