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Inside The Outdoors
Sleeping Bag Guide: How To Choose A Sleeping Bag

Sleeping Bag Guide: How To Choose A Sleeping Bag

27.03.2024 | Camping Buying Guides

The right sleeping bag can make all the difference to a good night’s sleep whether you are camping in the UK summer or planning a winter adventure outdoors. In this sleeping bag guide we will take you through all the important considerations and key features to show you how to choose the best bag for you.


1. Sleeping Bag Season Ratings


Sleeping bag season ratings are designed to make it easier to choose your sleeping bag. Ratings range from season 1, designed for summer camping, to season 4, designed for cold winter nights.


Season Season Rating Use


1 Season Summer / Indoor use
2 Seasons

Late spring / Early autumn


3 Seasons Autumn/WinterNights Without Frost
4 Seasons



1 Season Sleeping Bags

Season 1 sleeping bags are designed for camping on warm summer nights, so are an ideal choice for those attending festivals. They are also great for indoor use such as kids sleepovers.


2 Seasons Sleeping Bags

Season 2 sleeping bags are designed for use in UK late spring and early autumn where nights can get cold. These sleeping bags are ideal for camping in the UK outside the summer months such as kids half term holidays. These bags are also great for those who feel the cold in the summer.


3 Seasons Sleeping Bags

Season 3 sleeping bags are designed for cold autumn and winter nights where there’s no frost. Perfect for those who are braving the weather for winter camping and those who feel the cold when they sleep.


4 Seasons Sleeping Bags

Season 4 sleeping bags are for use on cold winter nights where there may also be frost or snow on the ground. In this category you’ll find our down sleeping bags.


2. Sleeping Bag Temperature Ratings


The temperature rating is an important factor to consider when choosing a sleeping bag. The rating you choose will depend on where you’ll be using it and what temperature you are comfortable sleeping in.

Temperature ratings will be expressed in comfort (lower comfort and upper comfort limits) and extreme ratings. These are based on the outside temperature. For a comfortable night’s sleep consider the lowest outdoor temperature you’ll be sleeping in and ensure that temperature falls within the comfort range.

For example, a Summit 300 Winter Sleeping Bag:

Comfort Ratings

The ‘comfort’ rating refers to the optimum temperature you will feel warm and comfortable sleeping in when in a rolled up position. When the bag is used in any temperatures below the ‘comfort rating’ the user is likely to feel the cold. On average women feel the cold more than men so this rating is some degrees above the ‘comfort limit’ for a man.


Extreme Ratings

The ‘extreme’ temperature rating is essentially ‘the survival temperature’. Put simply, this is the very limit at which the bag will keep you alive without frostbite, or any other temperature related ailments. It is not the lowest temperature you will be comfortable in and you should not expect regular use of the bag at this temperature.


3. Down VS Synthetic


There are two key types of sleeping bag to choose from. Down sleeping bags are made with the fine under feathers from ducks or geese and synthetic sleeping bags, which are filled with man-made insulation, mostly poly-fibres.


Synthetic Sleeping Bags

Synthetic insulation is the most common type of insulation used in sleeping bags. A synthetic sleeping bag will be cheaper, easier to clean and require less care than a down sleeping bag. They also perform better when wet than down bags, retaining around 50% of their insulating ability when wet.

However synthetic insulation does not retain heat like natural down so for winter trips you may find them colder than a down bag.


Pros Cons

Retains insulation when damp/wet

Does not retain heat as well as down

Cheaper than down

Shorter life span

Easier to clean


Down Sleeping Bags 

The loft of down creates thousands of tiny air pockets which means that down sleeping bags are more effective at trapping warm air and retaining heat. The warmth-to-weight ratio of a down sleeping bag cannot be beaten by a synthetic bag.

The disadvantage of down is that it easily absorbs moisture when damp and when it gets wet the feathers lose their fluffiness and the heat insulating properties are lost. Down sleeping bags also take much longer to dry out than synthetic bags. For these reasons duck down sleeping bags are well suited to cold but dry conditions

Pros Cons

Excellent heat retention


Loses heat insulation ability when wet


Lightweight- better warmth to weight ratio


Takes a long time to dry out when wet


Wider comfort temperature range- making it suitable for cold and warm temperatures


More expensive


Long lifespan if looked after


Requires special cleaning


Easier to compress and packs small


4. Shapes, Weights & Sizes

Shapes & Weights

Regular Sleeping Bag

Regular Sleeping Bags

A basic sleeping bag will be rectangular or ‘envelope’ in shape with a zip around two sides.  These are roomier than mummy sleeping bags and can be fully opened and used as a blanket. Rectangular sleeping bags are best for warmer weather due to the spacious design, resulting in a cooler bag.

Mummy Sleeping Bag

Mummy Sleeping Bags

A mummy sleeping bag tapers towards the feet and is therefore more fitted than a regular rectangular bag improving heat retention. They are best for colder weather due to tighter body fit and inclusion of hoods.

Most mummy bags will be single but it is possible to buy left and right handed bags that can be zipped together to create a double bag. Our Microlite and Summit sleeping bags are good examples of this.

A mummy sleeping bag also weighs less than a rectangular bag. The packed size and weight of the bag should also be taken into consideration, as this is especially important if you plan to fit your sleeping bag into a backpack or will be carrying the bag long distances.


Long Length Sleeping Bags

The length of your sleeping bag should be taken into consideration when looking for the best one for you, regular sleeping bags from Mountain Warehouse are usually better suited to individuals under 6ft. If you’re over 6ft, you may want to look into getting a long length sleeping bag which measure 220 x 80 x 50cm. Long length sleeping bags are available in both regular and mummy style sleeping bags including our Microlite Sleeping Bags and Traveller 50. Each of our sleeping bags has a tag either saying R (regular) or L (long).

Extra Long Length Sleeping Bags

Extra Long Length Sleeping Bags are even larger measuring 230 x 105x 70cm, such as our Microlite Square XL Winter Sleeping Bag.

Double Sleeping Bags

Double sleeping bags measure 193 x 137cm and are designed to be shared by two people. You can find double sleeping bags in both synthetic and down materials.


5. Key Features


When choosing your sleeping bag, look out for the below features which will improve your comfort.


Baffles are the compartments in the sleeping bag that hold the filling so it is evenly distributed.


Inner Linings
Fine nylon or polyester are the most common materials used for lining sleeping bags. Flannel or cotton are also popular for sleeping bag linings, although lightweight and breathable cotton traps moisture so isn’t recommended for cold conditions.


Outer Fabrics
Outer shells are commonly made of nylon-ripstop as it is highly durable. Dryloft is a water resistant, breathable fabric that is often used for sleeping bags.


Left & Right Hand Zips
Sleeping bags are available with the zip opening on the right and left hand sides. To make it easier to unzip when you are in it choose a bag where the zip opening is the opposite side to your leading hand. If you are right handed choose a left bag and if you are left handed choose a right bag.


Two Way Zip
A two-way zip is useful for easy opening when ventilation is required. Zips can be full length or just half way. Two-way zips can also be used to create a double sleeping bag if you buy two of the same style and zip both together.


Zip Baffle
Heat can easily be lost through the zipped area of a sleeping bag, an insulated zip baffle (behind the zip) helps reduce heat loss.


Zip Cover
A zip cover (a piece of fabric that is normally fastened with velcro) covers the zip when the bag is fully zipped up helping to prevent the zip coming undone when asleep.


Much of your body heat is lost through your head, a shaped hood will help keep in heat. A draw cord closure allows you to pull the hood tight against your face for added warmth.


Draft Collar (or Neck/Shoulder Baffle)
An insulated draft collar (at the base of the hood) helps to stop body heat escaping from the bag and keeps out the cold around neck and shoulders. Most draft collars will have an adjustable draw-cord to tighten if necessary.


Inner Pockets
Normally found near the top of the bag. Handy for keeping valuables such as wallets and phones safely tucked away.


Stuff Sack
Mummy sleeping bags will come with a stuff sack with a draw string closure. Unlike a rectangular bag that can be folded a mummy bag should simply be stuffed into its bag. Compression straps help reduce the size of the packed bag.


6. Sleeping Bag Accessories


Although choosing the best sleeping bag for you is important, a few small additions can allow you to increase comfort and improve your night’s sleep.


Sleeping Bag Liners
Sleeping bag liners add extra warmth, improve hygiene and help to prolong the life of your sleeping bag. Available in a variety of shapes and sizes designed to fit your sleeping bag style. Our sleeping bag liners are lightweight and include a handy pack away bag.

Polycotton Mummy Sleeping Bag Liner

Shop Sleeping Bag Liners

Travel Pillow
Travel pillows are smaller and lighter than standard pillows, making them the ideal companion for any trip where space is limited.


Sleeping Mats
Sleeping mats and roll mats go under your sleeping bag and provide insulation from the ground to keep you warm when sleeping outdoors.

Ultimate Self Inflating Mat

Shop Sleeping Mats

Air Beds
Air beds will add a layer of home comfort to your sleeping bag setup.

Now you have a better idea of  how to choose the best sleeping bag for you, take a look at our range: