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Spotlight - equipment views and reviews from the AK team

How to Choose an Insulated Jacket

By Hati Whiteley
12, Jan, 2018

So much choice, but which is the right one? Worry not! This handy guide provides all the information you need for buying an insulated jacket.

© Alpkit

You don’t buy an insulated jacket every day. Well, maybe you do… but even so you probably want to buy the right one!

But what is right? How do you know which insulated jacket will work for you?

We cannot offer a simple one-size-fits-all answer (if only!). However, we can give you all the food for thought that you need to make an informed decision.

Okay, here goes…


What are you going to use it for?

The first step in buying an insulated jacket is working out what you want to use your insulated jacket for. What are you going to be doing, and where? What time of year will it be? What weather conditions are likely?

Giving a little thought to these questions will help you with the following considerations.

Sometimes, it's just about what feels right... Alpkiteer Anna Wells was rarely without her Apogee synthetic jacket when skiing through the New Year! Read her review here.


Filling: Down versus Synthetic 
When to choose down

You may have noticed that our jackets for the coldest conditions are all 100% down filled. Down is the best insulator for its warmth to weight ratio – per gram down will give you more insulation that synthetic fibres. This is because lofty plumes of down trap pockets of air inside the baffles, and still air is a great insulator that weighs literally nothing! If we were to make a synthetic jacket as warm as the Phantac, it would be far heavier and bulkier.

So if you want something that is as warm as it can be for as little weight as possible, choose down.

Crisp, cold days in the Peak District are perfect for bouldering (and for a Filo!)


When to choose synthetic

Extended use, bivvy trips, Scottish winter belays: sometimes you can’t avoid getting a bit damp and synthetic fibres excel in this environment. Synthetic insulations use synthetic fibres to trap air between layers of fabric, and are inherently hydrophobic which helps them retain these insulating properties when wet. This means synthetic jackets dry and recover much faster than down (yes, even better that Nikwax Hydrophobic down!) when the going gets damp.

If there’s a chance your jacket getting damp or wet, opt for synthetic insulation.


Down insulation Synthetic Insulation
High warmth to weight ratio Retains thermal properties when wet
More compact packed size Dries and recovers faster
Excellent for cold, dry conditions Excellent for damp or moist conditions (UK winter or when you're likely to be sweaty)


How warm?

Depending on what you’re up to, you’ll want different amounts of insulation.

Light to medium-weight jackets, such as the Filoment, Katabatic, and Heiko, are ideal for cool conditions or more active use in cold conditions.

Heavier jackets such as the Apogee, Filo, or Phantac are suitable for colder climates, lower output activities, or if you just really feel the cold.

Filoment: a lightweight down jacket ideal for moving fast and light


In the lighter end of spectrum, it can be hard to see the wood from the trees when differentiating between jackets. Here are our tops picks for different activities…

Warmth to weight: Don a down jacket (eg. the Filoment)

Packability and moisture resistance: Something synthetic (eg. the Heiko)

Comfort and breathability: An active insulation (eg. Katabatic)

Breathable or wind resistant?

All down and most synthetic insulation must be sewn inside ‘fibreproof’ fabrics to stop the down or fibres from poking out through the fabric itself. As a result, these fabrics are completely windproof: great for cutting out the chill, but not so breathable.

In theory, if you are cold enough to be wearing a warm down jacket, breathability is much less of a concern than warmth. In practice, however, your output levels are likely to change over the course of the day, in which case you may be looking for something a little more breathable.

Fortunately, there’s a solution! Some synthetic insulations have been designed to be ‘migration resistant’, such as Primaloft Gold Active. This means they can be used with non-fibreproof fabrics… Fabrics that are more breathable. Jackets with this technology are ideal for active use over a wider range of temperatures, preventing that annoying ‘on again, off again’ thing… This is where the Katabatic fits in.

Ideal for when you're active in cooler conditions... Indeed, Fran is rarely seen without his Katabatic


Hood or no hood?

Hoods are great for keeping your neck and head cosy, warm, and protected from the wind. However, they can get in the way when layering below other garments and make your jacket less packable. Ultimately though, it comes down to personal preference.

A lightweight synthetic jacket with no hood, the Heiko is Hebe's first choice!



Optimum fit depends on usage. If you plan on wearing your jacket over lots of layers, a relaxed fit or bigger sizing make layering comfortable. If you plan on wearing your jacket below other layers, a snugger fit will fit below other layers better.

Weather Resistance

Generally speaking we avoid getting our insulated jackets wet when out and about, but occasionally we’re caught out by the weather.

Although not intended for keeping the rain off, some insulated jackets use a water resistant fabric for extra protection. This doesn’t make them waterproof as the stitching lets water through, but gives a little assurance against the rain. Jackets with less stitching, such as the Apogee, will be more be more weatherproof than the Phantac, as the latter has baffles.

The Phantac, our most technical down jacket, is ideal for those Alpine adventures



Often the deciding factor! Generally, the more specialist the jacket, the more technology required to create it, and the higher the cost. As a result, more technical jackets like the Phantac and Katakbatic will be priced higher than less specialised jackets.

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