How to Buy a Winter Sleeping Bag
Buying a sleeping bag is overwhelming, with so many big words and things to consider like grams of down and fill power, not to mention shape and temperature ratings. Plus, when buying a sleeping bag for the cooler months, you have the added pressure of needing to get it right because nobody enjoys sleeping cold. Especially when you've been out facing the harsh winter elements. Where do you start when you need a sleeping bag for cold conditions? This guide is where you start. Watch the video below and let Chris run you through things to look out for when buying a winter bag.
About Down
Down is the fine, fluffy feathers found under a bird's tough exterior feathers. The fluffiness of down is what traps air and that trapped air is what acts as an insulator that keeps you warm.
Fill Power vs. Grams of Down
Fill power relates to the loft and how lofted the down is. Think of it as the fluffiness of the sleeping bag. So, if a sleeping bag is 400 loft, it'll be that fluffy. The higher the loft, the fluffier the sleeping bag is. Grams of down refer to the physical weight of the down filling the sleeping bag.
Consider the fill power and grams of down together when looking for a winter sleeping bag. A sleeping bag with 1000 fill power of down would be lovely and fluffy, but if the down only weighs 100 grams it won't be very warm. Typically, winter sleeping bags have a high fill power and over 700 grams of down. This means your winter sleeping bag will be bulkier and heavier than your lightweight summer sleeping bag. A good winter sleeping bag will typically weigh over a kilo.
Temperature Ratings
The EN Standard is used by most sleeping bag manufacturers to assess the temperature rating of sleeping bags. The standard has three ratings: comfort, limit or transition and extreme.
The comfort rating is the temperature to which a cold sleeper might feel comfortable. The lower limit or transition rating is the limit of comfort, meaning you will be starting to feel cold. The extreme rating is the worst-case scenario. At this temperature, you will feel cold and risk becoming hypothermic.
It's important to note that temperature ratings include wearing thermals. How warm you sleep is also affected by variables like how tired you are, how well fed you are, how hydrated you are and the quality of your sleeping mat. So even though your sleeping bag might be rated to a minus ten comfort rating, you could feel cold if the temperature is just into the negatives.
Sleeping Bag Features
The hood is an important consideration when buying a winter sleeping bag. The temperature ratings above are tested with the hood fully enclosed around the face to trap body heat. Most people prefer to sleep with a pillow on top of the hood with just the draught collar cinched in, which means you won't achieve the temperature rating suggested by the sleeping bag manufacturer.
Winter sleeping bags have a draught collar that, like the hood, stops the warm air circulating around your body from escaping. The draught collar is an extra baffle of down in the neck area that sits over your clavicle. Some draught collars may have a drawcord to further synch in the bag around you.
Choose a sleeping bag with an extra baffle of down running alongside the zip to stop any heat from escaping. Most winter sleeping bags will only have one zip down the side. Some may have zips on both sides, risking heat loss. However, double zips allow the sleeping bag to be opened up for venting should you be too warm.
Generally, winter sleeping bags are mummy-shaped and for a good reason. The mummy shape minimises the extra air space in the sleeping bag keeping you warmer. However, if you are someone who moves around a lot in your sleep, you'll probably find it constricting. It's a tricky balance to get a sleeping bag that's both warm and spacious.