Sleeping Bag Buying Guide

Here at Capital Outdoors we stock a wide range of Sleeping Bags to suit a variety of uses and conditions. Having an inappropriate sleeping bag for the type of usage that it is required for can lead to a bad or uncomfortable experience.

With so many different Sleeping Bags available on the market from such a wide number of suppliers, knowing which Sleeping Bag best suits your needs for you can be a difficult decision to make. We have therefore put together this buying guide, explaining all of the things you need to consider when choosing which Sleeping Bag most suits your needs.

Season and Comfort Ratings

When buying a Sleeping Bag the most important thing to consider is the temperature of the environment in which you are likely to be sleeping in.

Having an unsuitable Sleeping Bag could either lead to being too cold or too hot, either of which can lead to an extremely poor night’s sleep. In the case of being too cold there are obviously additional risks involved from hypothermia which should be avoided at all costs.

For this reason Sleeping Bags are generally given Season and Comfort Ratings which indicate which temperature ranges they are suitable for.

Season Ratings

Season Ratings are a rough guide to the number of seasons that a Sleeping Bag is practical for throughout the year.

  • 1 Season – Temperatures of 5°C and higher: Summer season / warmer nights and indoor use.
  • Check out Kelty's Summer sleeping bag

  • 2 Season – Temperatures of approx. 0 to 5°C: Late spring / early autumn when the conditions are mild.
  • Check out Kelty's Spring/Autumn sleeping bag

  • 3 Season – Temperatures of approx. 0 to -7°C: Colder nights when the temperature starts to drop.
  • Check out our specially selected Kelty sleeping bag

  • 4 Season – Temperatures as low as -18°C: Very cold nights
  • Check out our specially selected Kelty sleeping bag for the colder season

  • 5 Season – Extremely cold Temperatures experienced on expeditions to some of the coldest parts of the world

Browse our range of Summer, 2 Season, 3 Season, 4 Season and 5 Season sleeping bags!

Comfort Ratings

In 2005 a standardised European comfort rating system (EN 1357) was introduced in order to provide a more specific and standardised guide to sleeping bag temperature ratings.

The EN rating system provides guidance in terms of the range of temperatures that a sleeping bag is effective within. These temperatures are classified for each sleeping bag as follows:

  • Upper limit - This is the highest temperature at which an average male user should experience a comfortable night’s sleep.
  • Comfort - This is the temperature at which an average female user should experience a comfortable night’s sleep. On average women sleep colder than men so this rating is some degrees above the ‘comfort lower limit’ for a man.
  • Comfort lower limit - This is the lowest temperature at which an average male user should experience a comfortable night’s sleep.
  • Extreme - This is a survival rating where the user is likely to suffer health damage such as Hypothermia. It should be treated with the utmost caution and not be relied upon for general use.

When buying a Sleeping Bag you should always bear in mind that it is better to have a bag that is too warm than too cold. In a situation when you are too warm you have a variety of options such as leaving the bag unzipped or even sleeping on top of the bag if you have to, if you are too cold the options available to you are more limited, one option would be to use a sleeping bag liner for additional warmth.

Check out our specially selected Kelty sleeping bag liner.


Depending on where you are using your sleeping bag weight may be a factor you wish to consider. For backpacking and hiking trips a lighter sleeping bag with a smaller packed size is advantageous, as reducing the weight that you have to carry and the amount of room taken up in your rucksack is a key consideration. Generally, the higher the warmth rating of a sleeping bag the larger the volume and weight however a lot depends on the materials that the Sleeping Bag is made out of.


Sleeping bags tend to be filled with either down or synthetic insulation, the properties of these two insulation types directly affect the weight, compression characteristics and volume of the Sleeping bag.


Down is the fine layer of feathers below the normal feathers on water fowl (duck or goose, normally). Down has great insulating properties and provide good levels of heat retention without the need for bulk.

Down Sleeping Bags are therefore generally lighter than Synthetic Sleeping Bags with the same temperature rating and they are easier to compress meaning that they can pack down into a smaller bundle for transportation.

Down Sleeping Bags do however carry a premium over Synthetic Bags and are generally more expensive.

Whilst lighter and more compressible, Down Sleeping Bags don’t perform well when they get wet as the feathers absorb moisture and loose some of their insulating properties, there are however an increasing number of sleeping bags on the market such as Kelty’s DriDown range which use treated Hydrophobic Down which is water repellent.

Treated Down repels the water and therefore retains its insulating properties whereas untreated Down saturates the water and therefore the quality as an insulator would be seriously impaired.

Check out our specially selected DriDown Kelty sleeping bag.


Synthetic insulation is a man-made alternative to down which works in much the same way in that it traps and retains body heat however the volume of material required to provide the same level of insulation is generally much larger.

This obviously means that synthetic bags are more bulky however there is a definite benefit in terms of cost in that they are significantly cheaper than Down alternatives.

Synthetic Sleeping Bags are also more effective when wet. This also makes it easier to store and wash than down filled sleeping bags.


Sleeping bags come in a range of shapes, sizes and lengths and they are all designed to keep you warm and comfortable whilst sleeping.

There are however two main types of shape that Sleeping Bags come in, Rectangular and Mummy.


Rectangular sleeping bags are a basic shaped bag which don’t generally have a hood.

Whilst they aren’t necessarily ideal for situations where you are likely to need the added benefit of being able to do a hood up to keep warmth in they do generally offer more room and are less constrictive than Mummy bags.

Rectangular are generally insulated with synthetic material and come in a wide variety of temperature variations however the warmer rated bags can often be very cumbersome and bulky are not ideal for back packing.

If however you are driving to the campsite and size isn’t as much of a consideration or if you are looking for a Sleeping Bag to use in a caravan then they are ideal.

Some brands also produce Rectangular bags designed for two people. Models such as the “Kelty Satellite - Double Wide” even come with a built in pocket attachment so that the bag can be secured to an air bed / mattress which helps you stay securely in place during the night.

Check out our specially selected Kelty rectangular sleeping bag.


Mummy shaped sleeping bags are designed to fit around the body, tapering towards the bottom. They generally include hoods to improve increase heat retention and to reduce heat loss from the head.

Right and Left Handed

Sleeping bags are either Right Handed or Left Handed. This makes it easier to undo the zip, with the zip on the left side for Left Handed Sleeping Bags, and on the right for Right Handed Sleeping Bags. It is more comfortable to undo the zip with more reach, so if you are right handed, choose a Left Handed Sleeping Bag, and if you are left handed, choose a Right Handed Sleeping Bag.

Other Considerations

Some brands produce Sleeping Bags in standard and long variations, if you are taller than 6 ft. 1in. then you should consider buying a longer model Sleeping Bag such as the Kelty Cloudloft 20 – Long

Click here to see our specially selected Kelty sleeping bag.

When sleeping the majority of heat loss during the night is through conduction to the ground. It is therefore really important to ensure that you have a use a good sleeping map to provide an extra layer of insulation. Some brands such as Big Agnes offer both insulated and non-insulated models for use in warm and cold environments.

Click here to see our specially selected Kelty sleeping bag.

Check out our full range of sleeping bags!

We stock a varied selection of sleeping bags and sleeping bag liners in all shapes and sizes, including kid’s sleeping bags, mummy sleeping bags, couples double sleeping bags and more! Whether you’re on a family camping holiday, a hiking trip, or caravanning, visit the Capital Outdoors Sleeping Bag department and get kitted out.

Not sure about Tents? Take a look at our handy Tent Guide for more information.