How To Choose a Sleeping Bag

There are lots of decisions to make when you’re buying a sleeping bag. And there’s no one-size-fits-all option that’s perfect for every possible situation. Here’s how to choose the right sleeping bag for your next camping trip.

How to choose a sleeping bag

1. Decide what you need your sleeping bag for
2. How warm should my sleeping bag be?
3. What is down?
4. Is down better than synthetic?
5. What is a baffle?
6. What are the different shapes of sleeping bags?

What do you need your sleeping bag for?

If you’re going bikepacking and want to squeeze your sleeping bag in between your handlebars, pack size and shape is going to be your priority. Lightweight hiking trips in the mountains are all about weight. Altitude adventures need the cosiest, toastiest of sleeping bags. Or if you’re just setting up basecamp at your favourite campsite, comfort is king.

What's the lowest temperature you're likely to camp in?

If you never camp in winter, there’s no sense in buying the warmest sleeping bag money can buy. Equally, opting for an ultralight summer sleeping bag might be a risk if you want to camp in spring and autumn. The country you use it in will make a big difference too. Continental climates (e.g. central Europe, North America) can be baking in summer and incredibly cold in winter, even at lower latitudes.

What sleeping bag do I need for wet weather?

For extended or rainy trips, synthetic insulation – like in our Ultra sleeping bags – performs better when damp. It retains its insulating properties better than down. If you’re expecting wet weather, this could be the deciding factor for the type of insulation you need. The longer your trip, the harder it will be to keep your sleeping bag dry.

How much should I spend on a sleeping bag?

The main factor that affects sleeping bag price is the type and quality of the insulation inside. The good news is: the size of your budget might make all of these decisions for you!

How warm should my sleeping bag be?

The warmth of your sleeping bag depends on many, many, many things. Are you a warm sleeper? What’s the temperature like outside? But there’s so, so much more. Too much to say here! Take a look at our guide to sleeping bag season ratings to choose the right sleeping bag for the weather.

What is down?

Down comes from the underbelly of ducks and geese, a natural insulation layer that sits underneath their protective outer feathers. These light and fluffy ‘filaments’ trap lots of insulating air for very little weight. Down quality is measured by loft – the amount of space each down filament takes up. Think of it as a measure of ‘fluffiness’!

What is fill power?

Fill power (FP) is the scientific measurement of loft. The higher the number, the higher the loft, and the higher the quality of down. High fill power down has a better warmth-to-weight ratio and will be more compressible. The number represents how many cubic centimetres a gram of down lofts to. 750FP means that 1g of down lofts to 750cm³. Anything above 600FP should be excellent quality down.

What is fill weight?

This is how many grams of down is inside your sleeping bag. Sleeping bags often have the fill weight in their product name, e.g. PipeDream 400. Sleeping bag warmth depends on both fill power and fill weight – a 400g down bag with 750FP down might be warmer than a 500g down bag with 650FP down. 

What is hydrophobic down?

Hydrophobic down is any down that has been treated with a durable water repellent (DWR). When down gets wet, the down filaments absorb water, collapse and clump together, losing all their insulation. Hydrophobic down dries quicker and repels water and the moisture from your body for longer. You’ll still need to keep your sleeping bag dry, but this treatment helps it to resist damp and recover better. The DownTek™ PFC-Free Water Repellent Down we use stays dry for up to 13.5x longer than untreated down.

What is RDS-certified down?

The Responsible Down Standard is a voluntary standard that independently certifies ethically sourced down. The RDS logo guarantees that the down in your sleeping bag meets highest of animal welfare standards. At Alpkit, we only use RDS-approved or recycled down.

What's the other option?

Synthetic insulation - these man-made polyester fibres are designed to replicate the insulation and compressibility of down. Polyester fibres don’t absorb water so synthetic insulation keeps its insulating structure even when damp. There are lots of different brands and types of synthetic insulation. We use PrimaLoft® Gold, the highest quality of synthetic insulation available, and Thermolite® Ecomade, a really durable, long-lasting fill.

How is synthetic insulation measured?

Most brands measure synthetic insulation by grams per square metre – often written as gsm or g/m². However, because there are so many different types of synthetic insulation, gsm only really helps to compare between sleeping bags using the same brand and fill type. This is where the temperature ratings are useful, again.

Are down sleeping bags better than synthetic?

Both down and synthetic sleeping bags have different advantages. They’re the two types of insulation used to keep you warm – down feathers and synthetic insulation.

Down sleeping bags have the best warmth-to-weight ratio and are the most compressible. This means they’re generally better for backpacking, bikepacking or any situation where you’ll have to carry your bag a long way. This also makes them ideal for adventures in extreme cold environments. Synthetic sleeping bags are better for damp conditions or for repeated heavy use. Their insulation is much easier to wash and care for than down.

How long will a synthetic sleeping bag last?

Synthetic sleeping bags might last for 3-4 years. Down, on the other hand, can last as long as 10 years. But this, of course, depends on how much you’re using your sleeping bag and how much TLC you’re giving it. We’re all about loving your gear for longer.

Do down sleeping bags lose their loft?

They can - down sleeping bags can be less thermally efficient if they’re not looked after properly. When the down gets wet, or if it’s compressed too much too often, the down gets squished. And without the insulating pockets of air in between the down filaments, it won’t keep you as warm. Best practice? Look after your down sleeping bag and it’ll look after you. That means keeping your sleeping bag, clean, dry and lofted.

What's a sleeping bag baffle?

Baffles are the separate compartments that hold the insulation inside your sleeping. Baffles stop insulation from ‘migrating’ (sinking) to the bottom/sides of your bag and creating cold spots. There are two main types of baffle construction (this applies more to down sleeping bags than synthetic bags).

What is stitch-through construction?

This means that each baffle has been stitched all the way through the sleeping bag fabric. Stitch-through is the lightest construction and the most compressible, but it can create cold spots along the lines of the stitching.

What does box-wall construction mean?

Box wall construction uses a divider of fabric between each baffle so that each baffle is shaped like a… erm, box. Box wall construction allows the down to loft better. But the extra fabric does add weight and make it less compressible.

What are the different shapes of sleeping bags?

There are two main types of sleeping bag shape to decide between, depending on whether you prioritise lightweight warmth or sleeping comfort:

Mummy: These sleeping bags have a tapered shape that’s wider at the shoulders and narrows towards the footbox. They look just like an Egyptian pharaoh's sarcophagus! This is the most ‘thermally efficient’ shape (the easiest to warm up and keep warm) and the lightest. The ultralight PipeDream and Ultra sleeping bags have a highly tapered shape to save weight while the SkyeHigh bags have a more relaxed mummy shape. The AlpineDream and ArcticDream leave extra space so you can wear more layers inside your sleeping bag.

Rectangular: These sleeping bags have much more space to spread out – not quite a ‘starfish’, but not far off either! Rectangular sleeping bags are better if you’re sleeping on a campsite for multiple nights in milder weather or in a bunkhouse/mountain hut/cold hostel. You can often zip these sleeping bags together to form a double bag, like with our Cloud Nine.

Do I need a right-zip or left-zip sleeping bag?

We offer left and right zips on all our sleeping bags. It’s easier to reach across your body with your lead hand to unzip your sleeping bag. Left zips are better for right-handers and right zips are better for lefties.

Hoods, neck baffles and zip baffles

Make sure the hood fits snugly and is easily adjustable. Most sleeping bags also include adjustable neck baffles to stop cold air being sucked in when you move. Zip baffles stop draughts from squeezing between your zip teeth.

Happy Camping!