Those searching for a sleeping bag for backpacking are in the camp where weight becomes a primary concern. Although we all want a lightweight sleeping bag that we can easily carry up into the mountains, what’s actually important is the warmth to weight ratio. Several factors affect this. From temperature rating to the type of insulation, and from the shape of the sleeping bag to any additional features it includes, there’s a lot to evaluate before you decide. Let’s jump in!

Sleeping bag temperature rating

The rating of a sleeping bag specifies the lowest temperature at which the average person will remain warm inside. They consist of 3 types.

  1. Summer (0°C and above)
  2. 3-season (-10°C - 0°C)
  3. Winter (-10°C and below)

Ideally, when choosing a sleeping bag for backpacking, you should select one with a rating just below the coldest conditions you expect to experience.

One issue with these generic ratings is that everyone’s body reacts slightly differently to temperature, and many find these ratings to be quite subjective. Those who desire a deeper understanding of how exactly they’ll feel in a particular sleeping bag choose to refer to terms known as “ISO” and ”EN”.

Sleeping bags with these temperature ratings undergo standardised tests, meaning they can be directly compared. Both “ISO” and “EN” are comprised of 2 different ratings, namely comfort — which refers to the lowest temperature a cold sleeper will remain comfortable at — and limit, the lowest temperature a warm sleeper will remain comfortable.

Sleeping bag insulation type

The insulating material used in sleeping bags comes in two main types, namely down and polyester. With either, the goal is to obtain consistent and even distribution of heat around the body. Both options come with advantages and disadvantages.

Down Insulation

Down is more expensive than synthetic insulating materials. But with that comes a material that’s lighter, more compressible and much more durable. A quality down sleeping bag should perform consistently for years to come without losing its insulating ability. The quality of the down used is specified by a term known as “fill power”. Higher numbers mean higher loft and greater warmth for a given weight.

One downside commonly associated with down sleeping bags is their inability to insulate when wet. Though this can be counteracted when a water-resistant treatment is applied to the down.

Synthetic Insulation

A much more affordable solution, synthetic insulating materials offer excellent insulation. Unlike down, they continue to insulate even when wet, meaning they are great for damper climates. The most common material used in synthetic sleeping bags is polyester.

Sleeping bag weight

If you’re looking for a sleeping bag for backpacking, then weight is always going to be a primary concern. The 2 biggest factors that affect sleeping bag weight are the insulation used and the shape of the sleeping bag.

Sleeping bags are often rated by a term known as insulation fill. Bear in mind that this parameter only tells you the weight of the insulation, not the actual sleeping bag. When carrying a sleeping bag up the side of a mountain on a backpacking trip, be mindful that it’s the overall weight of the sleeping bag that matters.

The shape of a sleeping bag greatly affects weight as well as warmth and comfort, where a slender, tighter sleeping bag can maintain warmth much more efficiently than a larger one. Most sleeping bags come in 3 main shapes — mummy, semi-rectangular and rectangular.

Mummy sleeping bags with their tapered design are aimed at reduced weight and increased warmth. Semi-rectangular sleeping bags are barrel-shaped and offer a compromise between warmth and spaciousness inside. While rectangular sleeping bags offer much more internal space, but with increased weight. Those going on a backpacking trip, where weight is a primary concern, may prefer to opt for mummy or semi-rectangular sleeping bags.

Useful features in a sleeping bag for backpacking

Sleeping bag hood: If you’re hiking at high altitude, then a sleeping bag with a hood can provide additional warmth for when the mercury goes south. Some sleeping bags come with a cord to adjust the fit around the hood for optimal insulation on colder nights.

Pillow pocket: When backpacking, as weight is a primary concern, few will want to carry a pillow. Some sleeping bags come with a pocket that can be filled with stuffed clothes so as you can make your very own pillow!

Draft blockers: On some sleeping bags, draft tubes exist the length of the bag directly behind the zipper. Designed to keep warm air from escaping, they do a great job of maintaining a stable temperature inside the sleeping bag. They’re a great option in exposed areas where cooler nights are to be expected.

At Decathlon, we stock a wide range of sleeping bags for all seasons and disciplines. Whether you require a lightweight mummy sleeping bag, or a simple rectangular sleeping bag for maximum space and comfort, we’ve got everything you need for your next backpacking trip!