Sleeping bag: all you need to know

Material: down or synthetic fibre

You want your sleeping bag to keep you warm, and you’d prefer it to be light, but also strong and robust. Deciding between a down sleeping bag and a synthetic fibre one isn’t easy. Here are some tips to help you decide.

Down sleeping bag

• Light, good balance between warmth and weight

• Small packing size

• Pleasant sleeping experience due to down absorbing moisture, however, down loses its insulating level very quickly if it gets too damp

• Quite high-level care requirements

• Very long-lasting with the correct care

• Contains animal product

Synthetic fibre sleeping bag

• Insulates even when damp

• Robust, easy care requirements

• Dries quickly

• Tends to be cheaper than comparable down sleeping bags

• Heavier, larger pack size

• Less durable than down as synthetic fibre loses its insulation properties more quickly

So, it all depends: if you are travelling to cold and dry places, a down sleeping bag is probably the right choice for you. The same applies if you want to travel light. But if a humid, tropical area is on your itinerary, then a synthetic fibre sleeping bag might suit you better.

Sleeping bag size

It’s no fun carrying a sleeping bag with you that is too big. You’re just lugging extra weight around and on chilly nights you’ll get cold quicker because your body warmth spreads itself out more in a large sleeping bag. But your bag musn’t be too small, either. You want to be able to tuck your shoulders and head in. Also, you’ll flatten the insulation material more quickly in a small sleeping bag (with down and synthetic fibres). So the rule of thumb is this: when you are lying fully wrapped up in the sleeping bag and sitting up, it shouldn’t be stretched anywhere. In cold temperatures, you should also choose a slightly larger sleeping bag so you can keep your clothes or important items warm at your feet.

Temperature and fill power

You really don’t want to wake up shivering in the middle of the night. Sweating isn’t pleasant either. Remember, it’s not the sleeping bag that keeps you warm, it’s your own body. The sleeping bag just provides insulation. And the bigger the sleeping bag, the more air you’ve got to keep warm.

For down sleeping bags, the higher the fill power the greater the down insulation level – at least with the same outer material. Fill power is given in cuin. This figure tells you how many cubic inches one ounce of down can expand to after it has been compressed. And the higher this figure is, the greater the amount of insulating air that is trapped. This is why it is important to spread out your sleeping bag before you go to bed. This lets the down expand. Also, make sure you have an insulating mat. The mat keeps the cold from the ground at bay. If you have a poor mat, you will probably get cold even in a good sleeping bag.

If you go for a high fill power product, it will contain less down because the down is high quality. If the fill power is low, you need more down for insulation. This makes the product heavy and bulkier. We define good-quality down as having a rating around 800 cuin or above.

Synthetic fibres don’t have warmth ratings in cuin. The manufacturer specifies a warmth category based on various tests. Winter sleeping bags keep you warm at temperatures down to around -18 degrees, summer sleeping bags are comfortable from around six degrees and three-season sleeping bags from minus four to five degrees.

Temperature indications are made by manufacturers based on the following scale: Comfort means that an average woman is only just warm enough. Limit indicates that an average man in thermal underwear will not quite wake up. And extreme means that you may get frostbite, but you will survive the cold. Given the relative vagueness and the highly individual nature of all this, Transa corrects the values by about three degrees based on our own experience.

Sleeping bag shapes

Depending on its shape, your sleeping bag may be better suited for a trekking tour with light baggage or for a summer holiday with a car and tent. The following overview shows you the most common types of sleeping bag and their pros and cons.

Sleeping bag weight

If you carry your sleeping bag with you all day while out trekking, packing size and weight are crucial criteria. When you’re camping with a vehicle, this is less relevant.

Light summer sleeping bags are available from weights of about half a kilo. Sleeping bags for low minus temperatures weigh up to three kilos.