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Buying Guides – Sleeping Bags

After a long day reaching your destination, nothing beats the feeling of snuggling into a warm, comfy sleeping bag, ready for a good nights sleep in preparation (and anticipation) for a new day. Having the right sleeping bag can be the difference between waking up refreshed and ready for another great day and not sleeping at all. Here we give useful advice and tips to help you choose the best bag for a good nights sleep.

Quick Tips

  • Decide what the lowest temperature is that you are likely to encounter. Choose a bag that will perform to this temperature (and ideally a little below for extra peace of mind).
  • Synthetic bags tend to be cheaper and easier to clean than down bags. They also provide reasonable insulation when wet and dry out more quickly than down bags.
  • Down bags provide the best warmth to weight ratio, compress smaller and will last longer than synthetic bags.
  • A mummy shaped bag will provide the most efficient insulation compared to a rectangular bag which will give more space to move around in (but also to heat up).
  • A sleeping bag is no good if you don’t have insulation from the ground; use a suitable mat to get the most from your bag.

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Which type is for you?

Weight vs. Warmth vs. Bulk vs. Cost

The above equation is the one you should consider when buying a sleeping bag. It’s important to decide which factor(s) is the most essential as this will influence the model you choose. Generally the more expensive or advanced a filling the more compact and lightweight the bag will be.

Sleeping bags can be divided into the following broad categories.

  1. Trail – Trail sleeping bags are ideal if you are away for only a few days at a time or when space in your rucsac is not so important. A good trail sleeping bag should be reasonably light and not too bulky depending on what time of year it will be used. If you are away for only a few days then you can allow for a slightly bulkier bag giving increased warmth. Usually synthetic filling is used to keep cost down.
  2. Trekking – Trekking sleeping bags are designed for longer trips where the total weight and pack size are more critical. They will make use of down or performance synthetic fillings to reduce the weight and bulk whilst maintaining a high level of warmth to weight.
  3. Mountain – Mountain sleeping bags may be specialist lightweight models for alpine use where the main aim is to keep bulk and weight to an absolute minimum. Equally they may be the extra warm bags required for temperatures in excess of -15°C. If you are intending to use a sleeping bag in extreme low temperatures for extended trips a vapour barrier liner will improve performance.

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Fillings - Down vs. Synthetic


Synthetic fillings are less expensive to produce than Down and less prone to losing their insulating properties when wet. Below are four typical fillings used across the Tiso range of sleeping bags:

  • Hollowfibre – a collection of Polyester fibres. The most basic but reasonably durable and easy to clean.
  • 4 hole Hollowfibre – based on the original Hollowfibre but with 4 holes through the centre of each Polyester fibre instead of one giving a greater surface area to trap warm air and providing more insulation for less bulk and weight.
  • Quallofil 7 – again a development of Hollowfibre, this material has 7 holes through each fibre, which reduces the weight of the bag further without compromising the level of insulation given.
  • Micraloft – sometimes called MTI loft, this material is made of very thin siliconised Polyester fibres which are layered up in very fine layers enabling manufacturers to build bags with many warmth giving layers while keeping the weight and bulk of the bag down to an absolute minimum.


Down filled bags are generally warmer and lighter than the equivalent synthetic bags and are still considered best for winter and expedition use where low weight and bulk are important. Care must be taken with all down bags as if they become wet they lose a great deal of their insulating properties. Another factor with down bags is that they must be washed with great care to prevent damage. They are more expensive but generally more durable and will last longer than synthetic bags. Down comes in the following varieties:

  • Duck down – less fine than Goose down but considerably less expensive. Down works by the feathers trapping a layer of air which is then heated by your body heat.
  • Goose down – very fine and provides approx. 25% more insulation than the equivalent weight of Duck down.
  • Hi-Loft down – This type of down is made from very fine Goose down and provides yet more insulation by trapping more air than any other filling. Used in some expedition bags where bulk and weight are critical.

Down comes in a number of different grades/qualities. For example, 90% Goose Down will consist of 90% down and 10% feathers. The higher the percentage stated, the purer the down and therefore the lower the weight and bulk and the better the insulation. However, the higher the grade, the more expensive the bag.

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Shell Fabrics

The fabrics used in sleeping bags is not designed to be waterproof but primarily to be very breathable to prevent the user from becoming too uncomfortable inside. Shell fabrics tend to become more durable and better quality as the price of the bag increases.

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Seasonal Ratings

At Tiso we consider that putting a temperature rating on a sleeping bag can be misleading for a number of reasons. Different manufacturers use different criteria to award their own ratings and every individual feels the cold differently too. For these reasons we give our sleeping bags a broader seasonal rating to give you an overall idea of the bags intended use based on typical UK conditions.

  • One Season bags – Basic Summer bags designer for use in warm weather or indoor use.
  • Two Season bags – General purpose bags for use from late Spring through into the early Autumn.
  • Three Season bags – Spring / Summer / Autumn bags for use down to freezing point and just below.
  • Four Season bags – Winter sleeping bags for use at low temperatures and in harsh conditions.
  • Four Season plus / Five Season bags – Specialist bags for expedition use, these are probably too warm for most activities in the UK.

Factors that affect your temperature in a bag

When using a sleeping bag there are a number of factors that will affect how you as an individual feel the temperature.? They can be divided into two categories as follows:

Physical Factors
  • Environment, altitude and climate. Where the bag is being used is important in choosing the right model.
  • Insulation from the ground. Conduction through the base of the bag can be a major factor when sleeping in the cold. Selection of the appropriate mat and sleeping position can make a big difference in your comfort.
  • Insulation from wind chill, respiration and moisture loss through breathing can affect how you feel the cold in the bag.
  • Where is it being used; in a tent, hut, bothy (concrete floors are colder than wooden), bivi-ing, in-house use.
  • What is the user wearing in the bag; lightweight base-layers, expedition weight base layers, down suit, hat, gloves, socks, scarf.? Wearing warm socks and a hat in cooler weather can keep the extremities warmer and help you to stay warmer.
  • Features of the bag; hood design, neck baffles, zip baffles, foot plug design, shape and fit.
  • Extended trips can lead to moisture from sweat becoming trapped in the bag reducing the insulation it can offer.
Physiological Factors

Sleeping bags do not generate any heat. A sleeping bag works by retaining a layer of warm air that you generate around you; this is what keeps you warm.

  • Age – older people feel the cold more than young adults. Also, young children cannot self regulate their temperature very well.
  • Males & females feel the cold differently – females are generally more susceptible to cold than males.
  • Physical fitness & condition – seasoned mountaineers can generally sleep at a colder temperature than those who camp infrequently. Also, they are more used to it.
  • Build of the user – a slim man at 5’6 will fit the bag differently to a large 6’ tall man and may find the bag correspondingly feels warmer or cooler.
  • Body Weight – A light layer of body fat insulates you against cold. In addition, the larger the body, the ratio of surface area to mass reduces making it harder to lose heat.
  • Keeping well nourished and hydrated during a trip makes a big difference. If you are dehydrated and hungry your body may not maintain the correct temperature.
  • Exhaustion reduces the body’s ability to maintain temperature regulation.
  • General health – there are medical conditions that may make the user more susceptible to the cold; e.g. circulatory problems can affect the perception of cold.

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Design Features

  • Shape – most modern sleeping bags are mummy shaped with cowl hood and a taper towards the foot; these features allow the maximum amount of warmth to be trapped inside the bag.
  • Shoulder baffle – another warmth saving feature. It allows the bag to be closed around the neck and shoulders with a draw cord (trapping more warm air) without restricting the face and head.
  • Zips – allow ventilation and ease of access. Most manufacturers make bags with left and right zip options allowing two (twin) bags to be zipped together. If you are right handed you are best to buy a bag with a zip on the left and vice versa as it is easier to do it up and down across your body.
  • Compression Bags – many sleeping bags come with a compression bag which is fitted with straps to enable you to squash the bag up smaller than it would normally go. These bags are also available to buy separately.

Once you have your bag, here are some tips on how to get the best from it.

  • Ensure it is used with the best camping mat available. Most of your heat and comfort will depend on what you sleep on.
  • Sometimes it is easier to pack your rucsac with a sleeping bag that is loosely compressed (allowing you to pack things more easily around it).
  • If using your sleeping bag regularly, it is a good idea to use a liner inside the bag. This keeps the bag clean and the liner is easier to wash than the whole bag.
  • Take care washing your sleeping bag especially if it’s a down bag. See our Care & Maintenance Guide for some useful advice and tips on looking after your sleeping bag.

See our Customer Services & Repair Guide for details of our aftercare service.

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