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Spotlight - equipment views and reviews from the AK team

How to Choose an Insulated Jacket

By Hati Whiteley
19, Nov, 2019

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.

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…

Our Top 5 Tips for Buying an Insulated Jacket

  1. Work out what you're going to use it for
  2. Choose the fill
    • When to choose down
    • When to choose synthetic
  3. Figure out how warm you need it to be
  4. Pick out your non-negotiable features
    • Breathability vs wind resistance
    • Hood vs no hood
    • Fit
    • Weather resistance
  5. Price


1. Work Out What You're Going to Use it for

The first step in buying an insulated jacket is working out what you want to use it 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 ultimately help you to decide on what that 'sweet spot' of jackets is for you, helping you to decide what's really important to suit your particular needs... and be honest with yourself!


2. Choose the Fill

When to choose down

Down is the best insulator for its warmth to weight ratio – per gram down will give you more insulation than synthetic fibres. This is because lofty plumes of down are naturally highly effective at trapping pockets of air inside the baffles. Still air is a great insulator, weighing literally nothing! If we were to make a synthetic jacket as warm as the Fantom, it would be much heavier and bulkier.

So if you want a jacket that is as warm as it can be for as little weight and bulk as possible, choose a down jacket.


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. Like down, synthetic insulation uses very fine fibres to trap pockets air between layers of fabric. Unlike Down, synthetic fibres are inherently hydrophobic (water repelling), which helps them to retain their insulating loft when wet. This also 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 more thermal properties when wet
More compact packed size Dries and recovers faster
Excellent for cold, dry conditions Excellent for UK conditions

3. Figure Out How Warm You Need it to be

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

Light to mid 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 0Hiro or Fantom are suitable for stationary activities in colder climates, lower output activities in very low temperatures, or just if you really feel the cold.

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

At 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 Hoody)

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

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

4. Pick Out Your Non-negotiable Features

Now you've figured out what you're using it for, what type of fill you need and how warm you need it, it's time for the fun stuff: picking out the key features that are most important to you and how you intend to use it.

Breathability vs. water resistance

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 insulation has been designed to be ‘migration resistant’, such as Primaloft Gold Active. This means they can be used with non-fibreproof fabrics, fabrics that are much 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, Rowan is rarely seen without his Katabatic

Hood vs. 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 Talini is Alice'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 squeeze 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 DWR-treated (durable water repellent) fabric for extra protection. This doesn’t make them waterproof as the stitching lets water through, and sustained rain will soak in eventually, but it gives you a little reassurance against the rain and a bit of extra time before you have to pull on your waterproof.

On the 0Hiro, we've added a 5K/5K PU waterproof membrane to the back of the durable nylon 6,6 outer fabric, providing extra protection from the elements. This makes it our toughest and most damp-resistant insulated jacket.

The 0Hiro, our safest jacket for ultimate weather protection: ideal for British winter adventures

5. Price

Often the deciding factor! Generally, the warmer and more specialised the jacket, the more technology required to create it, and the higher the cost. As a result, more technical jackets like the Fantom and 0Hiro will be priced higher than less specialised jackets with less fill. Because supply is more limited, down is generally more expensive than synthetic insulation.


Take a Closer Look at Our Range of Insulated Jackets

Down Jackets


Synthetically Insulated Jackets

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