Sleeping Bag Guide & Glossary 

Because comfort in the wild starts with the right bag
– and the right setup. 

How warm is a sleeping bag, really? 
Let’s clear this up: a sleeping bag doesn’t generate heat. It keeps the warmth you bring into it. The insulation – whether down or synthetic – traps your body heat and blocks the cold from creeping in. So, if you crawl in cold, it’ll stay cold until your body warms it up. And no, piling on layers won’t help. In fact, overdressing can block heat circulation inside the bag. 

Important: A sleeping bag alone won’t guarantee a good night’s sleep. You need a proper sleeping pad underneath to insulate you from the ground. Without it, even the warmest bag will struggle. Think of the pad as your mattress and thermal barrier – it’s non-negotiable. 

Understanding ISO 23537 Temperature Ratings 
All Nordisk sleeping bags are tested according to the ISO 23537 standard. This gives you a reliable, comparable, and realistic idea of how a bag performs in different conditions. Here’s what the ratings mean: 

Comfort Temperature 
The lowest temperature at which a person with average cold sensitivity (typically a woman) can sleep comfortably. This is your go-to number if you tend to get cold easily or want a good night’s sleep without surprises. The term "average cold sensitivity" should be interpreted cautiously. Please be aware that the strain of a long day outdoors or insufficient energy intake will make you feel colder. 

Limit Temperature 
The lowest temperature at which a trained and healthy adult can sleep through the night without waking from the cold. The ISO test refers to a standard male sleeper here. If you’re experienced and know your limits, this is your performance benchmark. 

Extreme Temperature 
This rating defines the outermost limit of the sleeping bag’s protective capability. At this temperature, the bag may help prevent life-threatening hypothermia, but freezing sensations and early signs of hypothermia can occur. It represents the final barrier between the user and a potentially dangerous situation. Use in this range is strictly for emergency survival, not for planned overnight stays. 

Maximum Temperature 
Not listed in our specs, because it’s adjustable. All Nordisk bags can be opened, vented, or used as a blanket. If it gets too warm, you adapt. 

Pro tip: 
Temperature comfort is personal. Factors like humidity, wind, your physical condition, energy levels, and even what you wear to bed all play a role. 

Choosing the Right Sleeping Bag 

Seasons & Conditions 

Summer Bags
Lightweight, breathable, and designed for warm nights. Perfect for festivals, bikepacking, or spontaneous overnighters. 

3-Season Bags
Your all-rounder. From spring chills to autumn frost, this is the most versatile choice for most outdoor adventures. 

Winter Bags
Built for the deep freeze. If you’re heading into snow, altitude, or Arctic conditions, this is your fortress. 

Shapes, Fit & Features 

Mummy
Snug and thermally efficient. Ideal for cold conditions and weight-conscious trips. 

Wide Mummy
A Nordisk favourite. More room to move without sacrificing warmth. 

Blanket
Classic and casual. Great for car camping or when flexibility matters more than grams. 

Length Sizing
Choose the right size to match your body length: 

• S – up to 160 cm 
• M – up to 175 cm 
• L – up to 195 cm 
• XL – up to 205 cm  

A proper fit ensures thermal efficiency and comfort. Too short = cold feet. Too long = wasted warmth. 

Zipper Placement
All Nordisk sleeping bags feature a left-side zipper. Blanket styles can be zipped together, as can most Mummy and Wide Mummy styles. Just keep in mind: when sleeping bags with hood are zipped together, one of the hoods will end up in front of the face – not under the head. Just flip it to the inside or out. 

Zipper Lengths
We offer several zipper configurations to suit different needs: 

Complete Zip 
Opens the bag completely, ideal for ventilation or blanket-style use. 

Side Zip
Partial side opening down to the ankle area with a closed-off footbox for better heat retention. 

Half Zip 
Minimalist design for ultralight packing and thermal efficiency. Some styles also feature shoulder zippers for improved operability and heat retention, or footbox zippers for increased ventilation when things get too warm.  

What Else Should You Consider? 

Weight & Pack Size 
If you’re covering distance or counting grams, every gram and litre matters. 

Insulation Type
Down is lighter and more compressible. Synthetic performs better in wet conditions. We offer both. 

Durability
A good sleeping bag lasts years. Choose one that fits your typical use – not just your next trip. 

Sleeping Pad Compatibility
Again: don’t skip the pad. It’s the foundation of your sleep system. 

Practical Tips for Better Sleep Outdoors 

• Shake out your bag before use to fluff the insulation.
• Warm up your body before getting in. A few jumping jacks will do the trick.
• Air out your bag in the morning to release moisture. 
• Store it loosely at home to preserve loft and maintain insulation performance.
• In cold conditions, wear a hat if you sleep with the hood open or off. It helps retain warmth where it escapes fastest.
• Avoid gloves and socks unless absolutely needed. Your body’s core heat will naturally warm the entire bag, including hands and feet.
• Wool underwear is ideal for sleeping. It regulates temperature and keeps you dry, summer or winter.