How to choose and buy the correct sleeping bag with

Author: Paul Howell   Date Posted:13 February 2015 

How to choose and buy the correct sleeping bag with

There are a few things you need to consider when selecting a sleeping bag

How warm does the sleeping bag need to be?

How much room do you need in the sleeping bag?

What fill do you want in the sleeping bag?

How warm does the sleeping bag need to be?

When thinking about how warm the sleeping bag needs to be:

  • Consider where you are going to be using the sleeping bag most and what the average night time temperature you are likely to encounter will be.
  • Think about whether you are a warm sleeper, tend to throw blankets off in the night or whether you feel the cold.

In recent years many sleeping bag manufacturers have adopted the European standard EN 13537 as a method of giving their sleeping bags a temperature rating
Most of the sleeping bags at are temperature rated using this standard. This gives a simple means by which sleeping bags from the same and different brands can be compared for warmth.

A sleeping bag rated using the EN 13537 standard will have three different temperature ratings. A “Comfort” rating, a “Limit of Comfort” Rating and an “Extreme” rating

Comfort rating: Based on a standard woman having a comfortable nights sleep.

Limit of Comfort rating: Based on the lowest temperature a standard man could have a comfortable nights sleep.

Extreme rating: A survival rating for a standard woman.

The comfort rating and limit of comfort rating are the ratings that need to be considered when buying a sleeping bag. The extreme rating for general consumer purposes can be disregarded


Sleeping Bag Temperature Rating Guide Today on many sleeping bag tags are diagrams similar to this one from One Planet. It gives and easy to understand guide to the temperature rating of the bag you are looking at.
From this diagram we can see that this sleeping bag would be suitable for a "standard woman" down to 0°C (Comfort rating) and -6°C (Limit of comfort) for a "standard man". The extreme rating is irrelevant when selecting the correct temperature rating required for general use.

The EN 13537 ratings are only a guide. All people are different  and feel the cold to differing degrees.
If you are a warm sleeper you can consider getting a sleeping bag a few degrees less warm than a standard person might buy for the same intended use. Where as if you feel the cold consider getting a bag that is slightly warmer.
For example, a man, who feels the cold, looking for a sleeping bag suitable for 0
°Celsius would be advised to select a sleeping bag that has a "limit of comfort" rating of perhaps -5°Celsius.
On the other hand a woman, who happens not to feel the cold so much, also looking for a 
0°Celsius bag could look for a bag with a "comfort" rating of maybe 3° to 5° Celsius.

There are a number of other factors that can effect your warmth while sleeping that are worth thinking about when purchasing a sleeping bag

Sleeping in clothes or thermals - This will keep you warmer

Wearing a beanie and socks - Keeping your head and feet more insulated can help keep you warmer

If the sleeping bag has a hood - A sleeping bag with a hood will help reduce heat loss from your head

Sleeping in a tent or bivvy - This traps still air around you helping to insulate you and protecting you from the cooling effects of breezes or wind.

Having a meal -  During a days hiking you use up a lot of energy. Replace this with a good meal at the end of the day and this will help give your body energy to keep warm

Stay hydrated - Stay hydrated to keep your body working efficiently, have a warm drink before you go to bed to help warm up

General Health - Circulatory problems or other health conditions may make you more sensitive to the cold. 

Using a sleeping mat - Any sleeping bag fill you lie on is compressed, it will not trap air amongst it's fibres and so will lose it's ability to insulate. Without using a well insulated sleeping mat you can lose a lot of warmth by conduction to the ground.

How much room do you need in the sleeping bag?

Sleeping bags come in three common shapes:


Rectangular Tapered Rectangular Mummy
Rectangular Sleeping Bag Tapered Rectangular Sleeping Bag Mummy Sleeping Bag
Pros: Pros: Pros:
Plenty of room to move around in the bag Some room to move around in the bag Most thermally efficient of all sleeping bags shapes
Can be unzipped to make large blanket Most tapered rectangular bags can be unzipped down the side and along the base to open up into a blanket, although smaller than rectangular bags Least material and fill used for warmth making them light weight compared to other shapes
  Tighter foot area makes it more thermally efficient than a rectangular bag. Less materials and fill means they will pack down smaller compared to rectangular and tapered rectangular bags of similar warmth
Cons: Cons: Cons:
Large air spaces inside the bag mean it is not the most thermally efficient Extra room at foot makes them less thermally efficient than mummy bags Tightly tapered towards foot restricts movement inside the bag.
More materials and fill used compared to similar warmth tapered or mummy bag increase the overall weight A roomier bag requires more fill and more materials to  make it increasing overall weight Most have no zip along the base so cannot be opened up to make a blanket
More materials and fill won't allow it to pack down as small as a similar warmth tapered or mummy bag More materials and fill increase packed size when compared to similar warmth mummy bag  
Rectangular bags are good for car camping and general travel A good compromise or thermal efficiency and roominess. Well suited to those requiring a little extra room in their bag for bushwalking, trekking and travel. The most thermally efficient shape of bag. Suitable for use in more extreme conditions and for those who don't mind the restricted space in order to get a lighter more packable sleeping bag.

What fill do you want in the sleeping bag?

Heat is radiated from the body. This heat warms the airspace surrounding the body. Trapped air, a good insulator, caught in the insulation of the sleeping bag helps retain that warmth in the airspace around the body.
The type and quality of fill used in a sleeping bag will determine how much air it can trap and therefore how warm the bag will be.
There are two main types of fill used in sleeping bags these are Down or Synthetic.

Down fill

Generally regarded as the best but most expensive sleeping bag insulation.
Down is the fine layer of feathers found underneath the outer feathers of birds. 
Throughout our range of sleeping bags the down used will either come from ducks or geese. The highest quality downs are sourced from free range geese from cold climates. 
The main advantage of a down sleeping bag compared to a synthetic fill bag is that the down is more durable and able to retain it's temperature rating over a longer time than a synthetic bag. It is also more packable and has better warmth to weight ratio than synthetic fill. Being a natural fibre it tends to feel more comfotable across a wider temperature range. The big disadvantage to down is when it gets wet it loses it's loft and clumps together no longer being able to trap air and therefore no longer insulating, it also takes a long time to dry out.

Two factors that will determine how warm a down sleeping bag is are the quality of the down and how much of it is used.

Down quality: 

Looking through the range of down sleeping bags on you will see terms like "700 Loft" and "80/20 Duck down"
Both these terms relate to the quality of the down.

Loft is a measurment of the volume a particular weight of down will occupy when "fluffed" up. Most manufacturers, to avoid confusion, have adopted the U.S. Loft rating, this is measured in inches³ per ounce (in³/oz). 700 loft down  means that 1 ounce of that particular down will occupy a volume of 700 inches³.
Down with a higher loft rating is therefore able to trap more air, insulate better, per unit weight and so less of it would be required to acheive the same temperature rating as the same sleeping bag using a lower loft down.
The only disadvantage to having a higher loft down in a sleeping bag is that it will push the price of the bag up.


One Planet Winter Lite -12 The One Planet Winter Lite -12 gives a good illustration of the difference down loft makes. It is available in both 800+ Loft Goose Down and 750+ Loft Duck Down.
To acheive a Limit of Comfort of -12°C One Planet use 756g of the 800+ Loft Goose Down but require 806g of 750+ Loft Duck Down to gain the same result. The finished duck down bag will be heavier and slightly bulkier than the goose down filled bag.
But the RRP's for the 800+ Loft fill Winter Lite -12 is about $100 more than the 750+ Loft version.

Down to feather ratio

"80/20 Duck Down" mean that the make up of the duck down being used is 80% down to 20% feather. The down, due to it soft fluffy nature, is a far better insulator than the relatively coarse feather. Therefore the higher the percentage of down to feather mix you have in a sleeping bag the better an insulator it will be for it's weight.

Synthetic Fill

Synthetic fills are generally made from polyester. The main advantages of synthetic fill sleeping bags are that they retain some of their insulating properties when wet and they are cheaper than down, but unfortunately will be less packable and weigh more than a similar warmth down sleeping bag.

The most common synthetic fills are:

Short Staple: Uses densly packed short strand filaments to trap air. It is softer and more compressible than continuous filament insulation but in general does not have the same long term durability.

Continuous Filament: Uses thicker longer continuous filaments. Generally regarded as having greater loft resilience and being more durable than short staple insulation.


Mont Synthetic Fill Sleeping Bag One Planet Synthetic Fill Sleeping Bag
The Mont Evo Light is filled with Polargurd 3D, a continuous filament. It has excellent warmth retention when wet, loft  resilience and long term durability One Planet use X-Static for the fill of their Sac -5. X-Static a short staple fibre makes the bag soft, flexible and  very compressible.

Sleeping Bag Shells.

Due to the fragile nature of down in wet and damp conditions. Manufacturers use more water resistant fabrics for the out shell of down sleeping bags designed to be used in damper environments, snow for example.
These more water resistant shells will increase the warmth of a sleeping bag slightly but they also reduce the breathability and increase the price of the bag.
If you want a down bag consider where it will be used and whether you will require a more water resistant shell. If using it for mountaineering, snow camping or you like to sleep out under the stars it is probably worth spending the extra money.

This guide is just a brief overview of the types of sleeping bags we stock at If you have any further questions with regards to selecting the suitable sleeping bag for yourself or have any questions on any specific sleeping bag we stock please feel free to either call us on 1800 303 353 or email us at

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