A sleeping bag is the one piece of gear you can't improvise around. Get it right and a cold night is just a cold night. Get it wrong and you're awake at 2 am, shivering, with nothing you can do about it until the sun comes up. Here's how to choose one for the trip you're actually doing.
1. Start with your coldest night
Sleeping bags are sold by temperature, and the number that matters is the coldest night you'll face: at the campsite, not the nearest town, and on the night the forecast gets wrong. Hills, valleys and inland camps are often several degrees colder than the town forecast, and Australia's high country can frost in any month of the year.
Pick a bag whose comfort rating is at or below that temperature. If you sleep cold, or you're not sure, add a 5°C margin. The chooser at the bottom of this page does the sums for you.
If you're torn between two bags, take the warmer one.
A bag that's too warm, you unzip. A bag that's too cold can't be fixed on the mountain, and a long night of being too cold can tip into hypothermia.
2. Match the bag to the trip
| Trip | Plan for | What suits it | Bags that fit, with a 5°C margin |
|---|---|---|---|
| Summer car camping, beach, festivals | About 10°C | An envelope bag or quilt: room to move, and it opens flat on hot nights | Black Ice E1000, Wind Hard Tiny Pro, or the light Aegismax Nano 2 |
| Coastal camping, summer huts | About 5°C | A light mummy or a quilt | Aegismax M3, Ultra Future I, Black Ice Z700 |
| Spring and autumn hikes, inland camps | About 0°C | A mummy with a hood | Black Ice G1000, Ultra Future II, Naturehike ULG700 |
| High country, where it can frost even in summer | About −5°C | A mummy with a hood and a draft collar | Black Ice Z1000, Naturehike ULG700 or ULG1000, Ultra Future II |
| Winter hiking below the snowline | About −10°C | An expedition mummy | Naturehike ULG1000, Naturehike Arctic-17 |
| Snow camping, ski touring | −15°C or colder | An expedition mummy, and a mat rated R 5 or more | Naturehike Arctic-23 (the Arctic-17 if you sleep warm) |
Comfort ratings on this site are the makers' own figures. Aegismax says it rates to the EN 13537 method; Black Ice and Naturehike don't say how they rate. That's why we add the margin, and why every bag's fill weight is on its page.
3. Mummy, quilt or envelope?
- Mummy. Tapered, with a hood and a shaped footbox. The warmest shape for its weight, and the one to take hiking or anywhere cold.
- Quilt. No hood and no back: your mat does the work underneath. Lighter and easier to vent, so it suits warm sleepers, side sleepers and people who feel trapped in a mummy.
- Envelope. Rectangular, and it unzips flat into a blanket. Heavier for the warmth, but roomy, which suits car camping and couples.
4. Read the three numbers
Fill weight is how much down is in the bag, in grams. It's the biggest single driver of warmth. Fill power (700, 800, 850) is the quality of that down: higher fill power gives the same warmth for less weight. Total weight is what you carry. Compare these before the temperature rating, because they're physical quantities. More on reading the numbers.
5. The rest of your sleep system
- A mat rated for the season. The ground takes more heat than the air, and down underneath you is crushed flat. As a rough guide, look for an R-value of about 2 for summer, 3 to 4 for three seasons, and 5 or more on snow.
- A liner. It keeps the bag clean between washes, adds a little warmth, and works on its own on hot nights and in huts. Our cotton liner.
- A pillow. Small, but it's the difference between sleeping and dozing. Our 85 g pillow.
- Dry clothes to sleep in. Dry thermals, socks and a beanie. Damp clothes pull heat out of you all night.
- A way to keep it dry. Wet down stops insulating. Pack the bag in its compression sack inside a dry bag or pack liner.
6. Sleep warm, stay safe
- Eat something before bed, and keep a snack within reach. Your body makes heat by burning food.
- Get into the bag warm. A short walk or a warm drink first helps: a bag holds warmth in, but it can't make it.
- On cold nights, cinch the hood and the draft collar, and keep your face out of the bag. Your breath is damp, and damp down is cold down.
- Tell someone where you're going and when you'll be back.
Know the signs of hypothermia
Hypothermia is when your body loses heat faster than it can make it. Early signs include shivering you can't control, clumsiness, confusion and drowsiness, with cold, pale skin. As it gets worse, shivering can stop: that's a warning sign, not a good one.
If someone is getting too cold, move them somewhere warm and dry if it's safe to, remove wet clothing, and warm their head, neck, chest and groin with dry blankets or a sleeping bag. Give warm drinks, but no alcohol. Don't rub their skin or use direct heat such as hot water. Suspected hypothermia is a medical emergency: call 000 in Australia (111 in New Zealand). This is general safety information, not medical advice; see healthdirect for more.
7. Look after it
- Store it loose in its large storage sack, never squashed in the compression sack.
- After every trip, air it out and make sure it's completely dry before you put it away.
- Wash it rarely, with a down-specific wash on a gentle cycle, then tumble dry on low with two clean tennis balls until there are no clumps left.