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How to choose the right sleeping bag
Finding the right sleeping bag is one of the most important steps in creating a comfortable and reliable sleep system outdoors.
Whether you’re heading into the mountains, moving fast through changing weather, or planning relaxed nights at a campsite, your sleeping bag should match both your environment and your personal needs.
This guide walks you through everything that matters: temperature ratings, insulation types, sizing, packability and key construction features.
Understanding sleeping bag warmth
All Robens sleeping bags are tested according to the EN/ISO standard, which ensures that temperature ratings are comparable across different brands. This standard gives three numbers: Comfort, Limit and Extreme.
The Comfort rating describes the temperature at which a standard woman can sleep comfortably on her back. This is the best reference point for users who sleep cold or prefer an extra safety margin.
The Limit rating reflects the temperature at which a standard man can sleep in a curled position without waking from the cold. It’s useful for experienced users who know their limits and want to carry less weight.
The Extreme rating is a survival-only number and should never guide your buying decision.
When choosing a bag, aim for a Comfort or Limit value that fits the lowest expected night temperature on your trip. Keep in mind that wind, humidity, fatigue and wet conditions all increase heat loss, so it’s wise to leave a small buffer.
Robens season ratings make selecting the correct sleeping bag easier.
1 season: For use in the summer months only
2 seasons: For use from late spring through to early autumn
3 seasons: For use from spring right through autumn
4 seasons: For use throughout all seasons but more suited to colder conditions
Down or synthetic
Which is right for you?
Robens offers both down-filled and synthetic-filled sleeping bags, along with hybrid models that combine the strengths of each approach.
Down insulation provides the best warmth-to-weight ratio and the smallest pack size. Robens uses responsibly sourced and fully traceable duck down, combined with high-quality shell fabrics and a differential cut that allows the insulation to loft fully without cold spots. Down is ideal for cold, dry climates or fast-and-light users who prioritise packability. It does, however, require more care and performs best when protected from prolonged moisture.
Synthetic insulation, used in the Moraine, Snowfall and Spire series, is more resilient in wet, humid or changeable conditions. It maintains warmth even when damp, dries faster and generally comes at a lower price point. Modern Robens fibres such as MicroThermo, OneThermo and MicroThermo High Loft provide impressive warmth and compressibility. Synthetic bags are a solid choice for general camping, shoulder seasons and environments where moisture is difficult to avoid.
Hybrid bags, such as the Gully series, combine down on the top side with synthetic insulation on the bottom. This design maintains loft where it matters most, while reducing heat loss through compression underneath and improving moisture performance in areas likely to touch the tent walls.
Sizing and Fit
A sleeping bag works best when it fits your height and body shape. Robens offers optimised sizing with Regular bags fitting users up to 180 cm and Long versions fitting users up to 195 cm. Choosing the right size makes your bag more thermally efficient, reduces dead air around the body and ensures you only carry the insulation you actually need. Shorter users benefit in particular from selecting a bag that isn’t unnecessarily long.
Construction features that improve performance
Beyond insulation and temperature rating, the construction of a sleeping bag has a major influence on warmth and comfort. Robens uses box-wall construction in down bags to avoid sewn-through seams and prevent cold spots. Many models feature a differential cut, where the inner liner is slightly smaller than the outer shell, ensuring the insulation can loft fully.
Hoods and neck baffles are carefully shaped to minimise heat loss, and differentiated drawcords allow adjustments by touch in the dark. Insulated zip baffles run the full length of the zipper to block cold air, while anti-snag guards keep the zip running smoothly. Footboxes are anatomically shaped in a shark-fin design, offering improved comfort and extra insulation around the feet.
Durable shell fabrics with ripstop construction increase resistance to wear and prevent small tears from spreading. All new Robens sleeping bags use PFAS-free finishes, providing water-resistant protection without relying on persistent chemicals.
Packability
Pack size matters, especially if you are hiking, bikepacking or mountaineering. Down bags offer the smallest packed volume due to their high loft and compressibility, particularly the ultralight models using 10–20D shell fabrics and high fill-power down. Synthetic bags pack slightly larger, but modern Robens fibres still compress well and remain practical for most outdoor activities. When comparing packability, look at the stated pack size as well as weight. Consider your activity: long-distance hikers and bikepackers often favour ultralight down bags, while weekend trips or car camping leave more room for synthetic options.
Outer materials
The outer materials used across the Robens sleeping bag range are carefully selected to balance durability, low weight and packability.
Ultralight models such as the Scoria series use a fine 10D polyester ripstop that keeps overall weight to a minimum while still offering reliable tear resistance.
The Couloir bags move to a stronger TORAY 20D nylon taffeta, providing a smooth, tough surface suited for colder and more demanding environments.
In the Serac series, a 20D 400T nylon shell delivers an excellent combination of durability and compressibility, while the Snowfall models upgrade this to a recycled 20D nylon ripstop for improved sustainability without compromising performance.
More robust designs like the Gully and Spire series use 50D polyester taffeta on the outside, offering enhanced abrasion resistance and long-term durability in mixed conditions, and the Moraine series features a blend of 40D nylon ripstop and recycled 20D nylon for a dependable yet lightweight shell.
Across the entire range, ripstop constructions help prevent small tears from spreading, and all shells are finished with PFAS-free water-resistant treatments, ensuring protection against moisture while reducing environmental impact.
Storage
Proper long-term storage is essential for keeping a sleeping bag performing at its best.
Down insulation in particular needs space to breathe, so a sleeping bag should always be stored loose in a large, airy bag and kept in a dry, well-ventilated place. All Robens down sleeping bags are delivered with both a generous storage bag and a separate compression stuff sack. This ensures that the down is protected all the way from the factory to the shop, and safely home to its new owner. The storage bag allows the insulation to remain fully lofted, preserving its warmth, structure and lifespan, while the compression bag is intended only for transport during trips.
Because sleeping bag outer fabrics are intentionally breathable to maintain a healthy sleeping climate, small feathers may occasionally work their way through the material. Never pull them out from the outside, as this can widen the weave and encourage more feathers to follow. Instead, gently pinch the fabric from the inside and draw the feather back into the bag; the tiny opening will close naturally as the threads settle back into place. This is normal behaviour for high-quality down products and does not indicate a defect or reduced durability.
Protecting your sleeping bag outdoors
Using a protective outer layer or an inner liner is one of the simplest ways to extend the life of your sleeping bag.
When sleeping directly under a tarp or fully outdoors, a bivy bag adds an essential level of protection against wind, moisture and insects. The Robens Mountain Bivvy combines a highly water-resistant, breathable top fabric with a fully waterproof base, creating a sheltered microclimate around your sleep system while still allowing condensation to escape. Its compact design fits both your mat and sleeping bag inside, shielding them from dew, rain splash and rough ground. This keeps your sleeping bag cleaner, drier and better insulated, especially on multi-night trips.
Inside the bag, a liner adds another layer of comfort and helps preserve the insulation. The Mountain Liner is easy to insert and remove, offering quick protection against sweat, oils and dirt – the main factors that reduce loft and shorten the lifespan of both down and synthetic bags. The liner can be washed frequently without affecting performance, while your sleeping bag stays protected and only requires cleaning less often.
Together, a bivy on the outside and a liner on the inside create a durable, modular system that keeps your sleeping bag performing at its best for years of adventure.
Choosing the right sleeping bag for your adventure
Start by considering the lowest temperature you expect to encounter and select a Comfort or Limit rating that suits those conditions. Decide whether down, synthetic or hybrid insulation best matches your environment and your need for packability or moisture resistance. Choose the correct size to ensure thermal efficiency and comfort. Then consider the features that matter most to you, such as hood design, zip placement, pockets, hybrid fill or the ability to open the bag flat.
Pairing your sleeping bag with an appropriate sleeping mat is essential, as EN/ISO ratings assume the use of a pad with suitable insulation. The right combination of sleeping bag and mat creates a complete sleep system that keeps you warm, dry and comfortable across the full range of conditions.
The right sleeping bag is a balance of warmth, weight, durability and comfort. With the Robens range stretching from ultralight quilts for warm summer nights to deep-winter down bags built for demanding conditions, you can always find a model that fits your needs. Understanding how temperature ratings work, how insulation behaves and how construction details influence warmth will help you choose confidently and sleep comfortably wherever your adventures take you.
