Everything you need to know about sleeping bags

Sleeping bag ratings, seasons, sizes, filling, features and accessories explained!



A good nights sleep is not only important for your physical and mental health but also sets you off on the right foot for your next day adventuring. There’s nothing worse than being sleep deprived so ensuring you are comfortable, warm and able to get some quality sleep is a must!


To help you decide on your ideal sleeping set up, we have given you a break down of the basics of sleeping bags.





Getting a comfortable nights sleep

When choosing a sleeping bag, your first step is to pick the right temperature rating / season to suit your adventure and for you individually. 


To help you decide, most sleeping bags come with an EN rating or Season guide. These should only be used a guide as your sleeping set up and own individual preferences will have an affect on your comfort. Things to also consider:


  • Sleeping Mattress / Pad: Depending on the R Value of your mat will influence how warm you will stay. 

  • Night Time Clothing: Your sleep wear will naturally impact on your overall temperature! 


  • Male / Female: Women generally feel the cold more than men. Many sleeping bags specify a comfortable temperature for men and women so be sure to check this out before you buy!

  • Weather/Season: Although debated, dry cold and wet cold supposedly makes a difference to how you feel, with dry cold being more bearable and wet cold feeling colder! Checking how cold the nights get where you plan on travelling is a must too. Even though your camping location can be exotic temperatures in the day, they can sometimes drop drastically at night!

  • Sleeping Bag Liners: An extra layer of insulation which also helps keep your sleeping bag fresher for longer!

  • Personal Preference: We’re all built differently and some of us feel colder more easily than others. If you know you’re still clutching on to your winter duvet well into Spring then perhaps selecting a bag which can withstand colder temperatures than standard is a better option!


An EN rating is a legal standard set up by the European advisory. These have been specifically set up to help standardise the temperature ratings issued across a wide range of manufacturers.


Sleeping bag manufacturers submit their products to be vigorously tested by an EN-certified laboratory to analyse how warm their bags actually are.  This means they end up with reliable, standardised and consistent results. The results are measured under four temperature ratings suitable for “standard” males and females.


The “Standard” male and female statistics the EN results are based on:


Standard Male: 25 years old, height 1.73m, weight 73kg

Standard Female: 25 years old, height 1.60m, weight 60kg

Maximum Temperature: This is the temperature in which a standard male is able to sleep without overly sweating. This is tested by having the hood and zippers open and their arms outside of the bag.


Comfort Temperature: A comfortable temperature for a standard female to be able to sleep in a natural position.


Limit Temperature: A night whereby a standard male can have an uninterrupted, non-shivering 8 hours sleep in the foetal position.


Extreme Temperature: The lowest temperature where the risk of damage to health by hypothermia is possible and is a point of danger which can lead to death.


Most bags will be rated according to the seasons which can often help guide you in your selection. Below is a chart to help you decipher them:

Season Rating

UK Season


1 Season


Ideal for indoor use or for a warm summers night camping with temperatures over 5°C.

2 Season

Spring / Summer / Early Autumn

Suitable for cooler nights with temperatures between 0 to 5°C.

3 Season

Autumn / Winter

Best for mild to cold nights with temperatures dropping from 0 to -5°C

4 Season


Ideal for cold winter nights, encountering frost and/or snow with temperatures as low as -10°C.

4+ Season

Super Insane Extreme Winter!!

For use when expecting to deal with temperatures descending to as low as -40°C.



Down Vs Synthetic Vs Hybrid

Sleeping bags are designed to keep you warm by reducing the rate your body heat dissipates into the night and creates a thermal insulation layer by trapping pockets of air around you which is then warmed by the body heat you produce. This means the performance of your bag will largely be defined by the quality of your insulating material, of which your options are either down (the very fine fluffy plumage found under the exterior feathers for geese or ducks) or synthetic manmade fibres (typically polyester). 

To help you figure out the differences and make a decision, read on below:


Duck, Duck, Goose!

Down is generally comprised of either duck or goose plumage, with Goose tending to be a more premium and expensive purchase with it’s higher fill-power rating than Duck which, although is a close second, has a lower fill-power rating but as it is sourced by manufacturers at a cheaper rate, is less expensive for the end-consumer.

Positives of Down Insulation:

  • It’s so Fluffy. Down insulation is made up of ultra fine fluffy plumage which is incredibly lofty, thus affective at trapping air and being a phenomenal insulator. If it’s good enough to keep our feathery friends nice and toasty, it’s certainly good enough for us! 

  • Durability. Down is renowned for being remarkably durable and can ordinarily take many years of being squished, fluffed and ruffled about and yet still remain highly affective without losing much in the way of it’s insulating properties.

  • Pockets. As down sleeping bags are compartmentalised into pockets this helps maintain your sleeping bags shape and evenly distribute the down, preventing clumping and loss of insulation in various areas.

Down Insulation

  • Light Weight and Compression. Being a lot lighter than it’s counterpart, as well as easier to compress, it’s often favoured by those who are conscious of weight and packing space.

Negatives of Down Insulation:

  • Dampness. On the ‘down’ side (pardon the pun), it is very absorbent so it can easily lose it’s fluffiness when exposed to damp conditions and thus reducing drastically it’s insulating qualities. On top of that, once it is damp, it takes a lot longer to dry out and can requires careful cleaning and washing attention. There are now hydrophobic down stuffing, which is treated to be water resistant but this comes at a price and still remains inferior to the synthetic options available.

  • Price. Even though down bags have come down in price over the last few years, they are generally much more expensive than synthetic alternatives.

  • Ethics. Down is a cause for concern for those who avoid animal products. Understandably, this can put an immediate strike through this option from the word go. 

Overview of Down Insulation:

If you’re hoping for a dry, non humid adventure, are okay with the ethnics of it being an animal product and have the budget, all whilst looking for something lightweight and compact, down may be a good choice for you.  With regards to the issues it has with dampness, some sleeping bag manufacturers have developed hydrophobic down to aid in repelling water, helping maintain it’s insulating properties so that’s always something to look out for. It’s worth ensuring you have a waterproof stuff sack to keep it dry during transportation.

Depending on how lofty (fluffy!) a specific down filling is affects how well it can insulate / trap heat. This is measured by calculating how many cubic inches one ounce of down can fill. The more space a one ounce of down can fill means the better insulation it can provide.




Filling 1 : 1 ounce of a 500-fill-power of down will fill 500 cubic inches of space




Filling 2 : 1 ounce of 900 fill power down will fill 900 cubic inches of space


So although they both weigh the same, the 900 is a lot more lofty thus filling more space and offering better insulation!  Goose can achieve higher fill-power ratings (up to 900) where as Duck tends to peak at 750 or 800, hence Goose being a more premium product for filling.





Synthetic FIbres


Manmade Fibres!

Synthetic fibres (ordinarily polyester) is the most popularly used fill for sleeping bags. Being inexpensive, durable and hypoallergenic, with quick drying capabilities it’s often favoured by most travellers.

Similarly to down, there are different types of synthetic fillings, all with fancy names from various manufacturers. They can ordinarily be split into two categories though to help you decide the best fill for you which are short-staple insulation or continuous filament fill.


Short-staple synthetic fill mimics the feathery down structure, with short and fine-denier filaments which are then tightly packed in to provide warmth. Although this provides a softer feel and offers good compressibility, the filaments have a tendency to break down a lot quicker when regularly packing away and unpacking meaning it can cause cold spots and need more frequent replacing.


Continuous filament fill is made up of long, continuous filaments which is thicker, stronger, lofty and durable. They are not as flexible or soft as their short-staple counter part and do not compress as well but they do hold their shape better, reducing the likelihood of cold spots arising.

Positives of Synthetic Insulation

  • Warmer in wet conditions. In a damp environment, being able to retain a good thermal conductivity is one of the most desirable traits of synthetic fillings. With it’s ability to remain lofty and dry quickly, synthetic manages to pip even hydrophobic downs when competing for warmth in wet weather.

  • Hypoallergenic. For those of you who suffer feathery allergies, synthetic will be the way to go, saving you from a puffy eyed, sneezy or much worse nights sleep.

  • Quick Dry. We’ve already mentioned it’s capability of remaining warmer when wet, but it’s worth mentioning again that it does dry much quicker than down. Washing and maintaining your bag is much easier.

  • Budget Friendly. Synthetic tends to be a lot easier on the pocket than down! 

Negatives of Synthetic Insulation:

  • Not as Squishable. Synthetic fibres just do not compress down as well as it’s feather compadre, particularly continuous filament synthetic fills.

  • Heavier. When matching the same warmth as down, there needs to be more synthetic fibres and thus, it’s heavier.

  • Replacement. Synthetic fibres break down a lot quicker than feathery plumage, so it’s insulating power I reduced every time it’s stuffed away. You will need to replace it sooner than a feathery filling.

Overview of Synthetic Insulation:

Synthetic filled sleeping bags are the most common on the market and certainly much better for those with tight budgets. Being heavier and less compressible, those with restricted space or weight limitations may favour the feathery fill options. However, if you’re facing damp and wet conditions, synthetic will be your best choice overall.



Mix and Match

A variety of manufacturers have now combined both water-resistant down and synthetic filling in order to achieve the best of both worlds. Within the bag, they are either blended together or alternatively separated and used in different areas to maximise the advantages of each fill. 

Positives and Negatives of Hybrid / Combined Down and Synthetic Filled Sleeping Bags:

Because it’s an in between option, when compared to down or synthetic bags they are sitting on the fence!

  • Weight. These bags are often lighter than synthetic filled sleeping bags but heavier than down!

  • Water Resistance. With the combined filling, they offer a more water resistant set up than stand alone down filled sleeping bag but naturally do not have the quick dry qualities of synthetic by itself.

  • Price. They can be expensive due to their unique qualities but more often than not sit somewhere in between the synthetic bags and down bags!

Overview of Hybrid / Combined Down and Synthetic Filled Sleeping Bags:

Bringing qualities from both sides, these type of filled bags can be a great middle ground to go for if you're undecided between synthetic and down. 




Rectangular Sleeping Bag

Barrel Sleeping Bag

Mummy Sleeping Bag

Double-Width / Quilted Sleeping Bag

Different shapes and sizes to suit!

Sleeping bags come in all different shapes, lengths and sizes. Picking the right one for you will make all the difference to your comfort, so below we’re given you a run through of the most popular available and sizing explained:

Sleeping Bag Shapes:

Rectangular Sleeping Bags:

Ideally for indoor use or camping in warm night temperatures, the regular / rectangular sleeping bag has squared off edges, offering more room and the ability to unzip it fully to make a large blanket. These tend to be heavier and bulkier than Mummy Sleeping Bags but offer a lot of wiggle about room for fidgety sleepers!

Barrel Shaped Sleeping Bags:

These bags are slightly tapered off at the top and bottom with more room for those who like to fidget or feel claustrophobic in Mummy bags but less room than the Rectangular shaped bags. 

Double-Width / Quilt:

Double-width / Quilt bags are suitable for two people to snuggle up in or under. Some are developed to unzip entirely to create two single rectangular bags or alternatively to create a large sleeping bag quilt. Popular as a duvet like spread on 4x4 campers with double beds. If you’re planning on buddying up, other bags can often be compatible to zip together. As long as you have opposite zippers of the same size and length then this is always an option (although it will create more cold spots than individual bags!)

Mummy Sleeping Bags:

As you can imagine from their descriptions, these bags are tailored in at the feet and then expand outwards to fit snugly around your hips and shoulders. Being a  much closer fit to your body their insulation capabilities are much improved to the rectangular shaped bags, although sometimes not as comfy to sleep in with restricted movement. They do tend to pack down smaller though and are often than not lighter than other shapes.

Women Sleeping Bags:

As we all know, we all come in different shapes and sizes, specifically when comparing men to women. As standard, women are more petite than men, specifically in the shoulder area and height so some manufacturers have tried to account for this by creating a women specific sleeping bags with shorter lengths and narrower shoulders but wider hips. They have also recognised women get colder than men so some have thrown in extra insulation in the footbox and upper body areas to keep the ladies snug.

Sleeping Bag Length:

Depending on the manufacturer, sleeping bags tend to come in Short, Regular, Long or X-Long. Each manufacturer will determine their own length to suit those sizes so when buying your sleeping bag be sure to check the recommended height for each bag and go to the one closest to your height! Many bags have added warmth sections in the feet compartment so if you opt for a bag too long you may be missing out on extra snugness for your feet!

Women Sleeping Bag



Unravelling the Mumbo Jumbo of the Sleeping Bag World


Sleeping Bag Zippers:

Most bags offer a choice between a left hand zipper or a right hand zipper in order to make your zipping up more easier. If you’re Left Handed, opt for a Right Handed zipper and if you’re right handed, a left handed zipper will be the best choice. Another reason manufacturers have opposing zippers is so some travellers can zip together their left handed zipper bag with a right handed zipped bag to make a bigger, double bag. Obviously, zip sizes and lengths have to be compatible in order to do this.


Two Way Zippers:

A two-way zipper allows you to open your bag from the inside as well as the outside so you don’t have to wiggle your arm free in order to unzip!

Inner Pocket / Stash Pocket

Draft Tube / Zip Baffle:

So you know that annoying bit of material you have managed to catch your zip in when zipping up a sleeping bag? If it’s not been your lining, it’s more than likely, that has been the draft tube or zip baffle! Despite thinking it’s only there to annoy you, it actually serves a purpose and is an insulated tube which covers the whole length of the zipper from the inside to help prevent heat loss… it’s not just there to test your patience! On a positive, many bags now provide a zip guard which helps prevent the lining from catching when zipping up or down!


Zip Cover:

A little cover that your zipper slips into so it doesn’t wriggle loose in the night or catches on any material / mats.


Sleeping Bag Hoods:

In order to keep heat escaping from out the top of your bag, hoods are sometimes built in to fit snugly over your noggin. Ordinarily, the opening of the hood can be scrunched up by a drawstring (or “differentiated cords”) to keep any gaping to a minimum. On some hoods, manufacturers have included a little pouch for you to stuff a pillow or clothing into as well – a nice little feature to look out for!


Draft Collar / Neck Baffle / Shoulder Baffle:

Situated around your head or neck area you may find an extra piece of insulated fabric which can be cinched up with a pull cord. This circles around your neck and shoulders and helps prevent heat loss.

Inner Pocket / Stash Pocket:

A little pocket normally nestled at the top of your bag, although this depends on your make and model, where you can stowaway any small items you may want to keep close to hand.


Sleeping Bag Pad Loops / Poppers:

Small, stretchy loops or poppers are sometimes sewn in around the edges of the bag and can be used to secure your bag with a matching sleeping mat. This helps prevent you from wriggling your way off the mat in the middle of the night. 


Sleeping Pad Sleeve: 
In order to reduce your sleeping bag pack weight and increase compressibility, some bags come with the insulation removed from the back and instead a sleeping pad sleeve in place whereby, you’ve guessed it, you can insert an insulated sleeping pad. As well as reducing down weight and size, it also helps prevent any slipping and sliding off your pad during the night.

Pad Loops / Poppers


At the foot of your bag, some manufacturers have designed a trapezoidal shaped footbox. This gives your feet a bit more room to comfortably fit in and reduces the tension which can be caused by your feet being squished into the bottom, thus helping maintain the sleeping bags insulation.




Sleeping Bag Linings:

Nylon / Polyester / Cotton / Flannel and Silk linings can be used as an accompaniment for your sleeping bag. Using a lining not only keeps your bag fresher for longer (it’s much easier to clean a thin lining than a whole bag), but also provides an extra layer of insulation for your sleep. 


Stuff Sacks:

To help pack away your sleeping bag, most come with a stuff sack whereby you quite literally, stuff in your sleeping bag. Although some people may be tempted to try and neatly fold up their bags, it’s actually better to randomly shove it into the sack to ensure the fibres are not creased and squashed into regular folds, thus losing insulating properties in those areas quicker. Stuff sacks normally have compression straps too meaning you can tighten them up once all the bag is stuffed in and reduce the size even more.





A sleeping bag is made up of an outer shell, inner lining and insulation. The outer shell of a sleeping bag is made up of a ripstop, highly durable nylon or polyester. These can be either waterproof or durable water repellent (DWR) treated and ordinarily are breathable. 


The inner lining is usually a breathable nylon taffeta or polyester, helping wick away body sweat and keep you warm.


The inner filling is made up of either synthetic fibres, down or a combination of both. They can be worked into the bag using a variety of methods, described below:


Quilted or Sewn Through Layers:

This is where the synthetic filling is stitched through from the outer shell to the lining in order to hold it in place. This does not effectively prevent cold spot areas and is commonly found in summer or indoor use sleeping bags only.

Offset Quilted or Offset Sewn Layers:

This method consists of two layers of synthetic filling: one stitched on to the outer shell and the other stitched in an offset pattern to the inner lining. This helps prevent cold spots.

Shingles or Wave Construction:

By overlapping smaller sections of insulation and stitching them together to make a layered affect, you create the shingled construction, much like a tiled roof. There is also the wave affect which is very similar to the Shingle construction. As opposed to using equal sized sections of insulation to overlap, an extra long section is used between two shorter ones but is then compressed to the same length as the shorter ones. This causes the finish to have a wavey affect. 

Shingle Construction

Wave Construction



With down filling, most manufacturers either create and join together multiple lightweight mesh or walled pockets, known as baffles, to keep the down in the right places and prevent it from gathering. There are a variety of baffle like techniques used, and sometimes bags have a variety of techniques combined.

Box Baffles:

Imagine long box shaped tubes with their walls joined together side by side. This is a boxed baffle technique. They can come in three different box shapes: a standard box like shape, a slant box shape (where the cross section shape is slanted like a parallelogram) or a trapezoidal box (a cross section looks like a tea cup facing upwards, with a teapcup facing downwards adjacent to it and repeat!). Box baffles can be layered and their joins offset, a bit like how bricks in a wall are offset, to help prevent heat loss.

Standard Box

Slanted Box

Trapezoidal Box

V-Tube Baffles:

V-Tube baffles are tubes, in the shape of a V, which are then interlocked with an upside-down V-Tube making a zigzag affect when looking at a cross section. Highly efficient at insulating, they can be slightly heavier due to an increase of baffle walls throughout.

Continuous Baffles:

In this case, the baffle in your sleeping bag (that little tube of insulation goodness) runs from one side of the zipper and loops all the way around you, underneath you and to the other side of the zipper. It’s one big, continuous loop, with only the zipper in the way. This means you can shift the down inside the baffle so you have more on top of you when you’re lying on your back in your sleeping bag, or you can shake it to gather in the baffle chamber underneath you. 

Continuous Baffles

Side Block Baffles:

To keep the down insulation separated and evenly distributed on the top and underneath of your bag, a side block is put in the baffles looping around you and is ordinarily situated on the opposite side of your zipper. This can be in the form of a thin fabric wall or an additional V shaped baffle that runs the length of your bag and stops the baffle from continuing all the way around. This is typically used in differential fill bags (see below!).

Side Block

V Shaped Block

Differential Cut:

This refers to how the linings are cut to make your sleeping bag. This specific cut is regularly used for Mummy Sleeping bags, whereby the inner lining is smaller than the outer lining. This allows the filling to expand outwards and be more lofty, helping improve insulation.

Differential Fill:

When lying on your back in your sleeping bag, this type of fill means there is more filling down the front / top of your bag and less underneath you. 

Stretch Baffles:

This is where the baffles are made using a stretchy fabric, helping it shape and form around the sleeper. 

Vertical Baffles:

As opposed to the baffles looping left to right around your body, the baffles run the full length of your body. This prevents down from slipping around to underneath you and can be used in the torso area only or for the entire bag.

Welded Baffles:

As opposed to stitching baffle in place, some manufacturers weld them to the linings. This helps maintain a stronger waterproof casing, with no stitching holes to worry about, and also improves insulation.


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