How to Choose an Insulated Jacket

Insulation is essential to keeping warm in the outdoors, and is usually worn as a mid-layer, or as the outer layer in dry, cold climates. It works by trapping the warmth that our bodies create to maintain our body temperature, but this can be achieved in a variety of ways. Choosing the right kind of insulation for your adventures will make sure you stay warm and safe in any conditions you might face.

Down insulation is made from the soft, fluffy feathers found beneath the tougher exterior feathers of geese and ducks. These feathers are prized for their exceptional warmth-to-weight ratio, making them ideal for high-performance jackets and sleeping bags.

• Source:

  • Goose down: Higher warmth-to-weight ratio, compresses smaller, and is generally more durable.

  • Duck down: More affordable but slightly less efficient at trapping heat.

• Fill Power:

  • Measures the loft (fluffiness) and heat-trapping capacity.

  • Higher fill power (e.g., 800+) = warmer, lighter, and more packable.

  • Lower fill power (e.g., 550) = bulkier but more budget-friendly.

• Advantages:

  • Unmatched warmth for its weight.

  • Highly compressible for easy packing.

  • Long-lasting if properly cared for.

• Water Vulnerability:

  • Loses loft and warmth when wet, as down clumps together.

  • Even hydrophobic-treated down (water-resistant coating) can’t match synthetic insulation in prolonged wet conditions.

• DWR Coatings:

  • Many down jackets include a DWR finish to repel light rain or snow.

  • Protects against brief showers but not heavy rain or submersion.

• Performance Context:

  • Best suited for dry, cold environments (e.g., winter hiking, alpine climbing).

  • Avoid for wet climates or activities with high sweat/rain exposure (e.g., trekking in humid regions).

• Wash with down-specific detergent to maintain loft.

• Store uncompressed in a cool, dry place.

• Reapply DWR coating annually to boost water resistance.

• Avoid fabric softeners, which clog down clusters.

Down insulation remains the gold standard for dry cold-weather gear, but always assess your environment and activity needs before choosing between down and synthetic. For mixed or wet conditions, consider a hybrid jacket with down in dry zones and synthetic in high-moisture areas.

Synthetic insulation uses man-made polyester fibres designed to mimic the structure of natural down by creating tiny air pockets that trap warmth. Unlike down, these fibres are inherently moisture-resistant, making them ideal for wet or high-activity conditions where staying dry is critical.

• Material: Composed of fine polyester strands woven into clusters or layered sheets.

• Function:

  • Traps warm air between fibres like down, but doesn’t collapse when wet.

  • Fibres are often hydrophobic, repelling water to maintain insulation.

• Key Advantage:

  • Retains 80–90% of warmth even when soaked, unlike down, which loses loft.

• Wet Environments: Rain, snow, or high humidity (e.g., coastal hikes, winter storms).

• High-Intensity Activities:

  • Ski touring, trail running, or mountaineering where sweat buildup is likely.

  • Synthetic dries faster and avoids the "cold clammy" feel of damp down.

• Budget-Friendly:

  • Generally cheaper than high-fill-power down, with better wet-performance value.

• Short-Staple:

  • Lightweight, budget-friendly (e.g., PrimaLoft Silver).

  • Used in mid-layer jackets and gloves.

• Continuous Filament:

  • Durable, high-loft fibres (e.g., Coreloft, Thermoball).

  • Common in technical outerwear.

• Biodegradable:

  • Eco-friendly options (e.g., PrimaLoft Bio) made from recycled materials.

• Machine-washable: Use mild detergent and tumble dry on low.
• Avoid fabric softeners: They coat fibres, reducing loft.
• Store loosely: Prevent permanent compression of insulation.

Synthetic insulation is the go-to choice for unpredictable weather, high-output activities, or budget-conscious adventurers. While less packable than down, its reliability in damp conditions makes it indispensable for UK climates, alpine ascents, or multi-day treks where drying gear isn’t an option. For hybrid performance, look for jackets with synthetic insulation in moisture-prone areas (e.g., cuffs, hood) and down elsewhere.

Less common and highly technical, these jackets draw on the strengths of down and synthetic fills to maximise functionality and weight savings. They commonly use synthetic fill in the shoulders and arms of the jacket, and down in the core body area. This is because synthetic fill retains its insulating characteristics better than down when compressed, for example by a rucksack on the shoulders, and if wetted out, which normally occurs first on the arms and shoulders. The use of down in the main body enables the jacket to remain highly packable and gives excellent warmth in the core.

Baffles are the containing sections of insulation. Their purpose is to prevent the material from gathering in the bottom of your jacket and evenly distribute the insulation across the jacket. The way the baffle is constructed can affect how well your jacket performs.

Wide baffles

Wide baffles are the warmest option as they contain more grams of down and can be constructed such that there are fewer seams where your body heat can escape. They can, however, feel bulky and do not layer well or compress down as small in your pack.

Narrow baffles

Narrow baffle or micro baffle jackets, as well as looking fantastic, work well underneath a waterproof in cold and wet environments and compress down small enough to stuff easily in your pack ready for you to pull out when you stop moving.

If you’re going to be using your jacket in very cold, low-activity environments then a jacket with an insulated hood may benefit you. Conversely, if you’re looking for a packable, lightweight garment to keep your core warm, then a hood may just add bulk and weight.

Still not sure which insulated jacket is right for you? Visit us in-store for advice from our experts.

Found your perfect insulated jacket? Check out our insulation care guide to keep it performing for many adventures to come.