Kathmandu Heli Down & Insulated Jackets – Tested & Reviewed

Aidan’s seeing double! Kathmandu offers its Heli jackets in down and synthetic insulated trims, so it seemed like the perfect chance to put them head to head and help you decide which one’s for you. They’re even the same price!

Kathmandu’s Heli jackets are a trusted staple for cross-season adventures and urban outings alike, but a heated debate (pun intended) remains between the OG duck down version – the Heli Down Jacket – and its newer synthetic variant – the Heli Insulated Hooded Jacket. Much has been written on the age-old feathers vs fibres divide, but when Kathmandu sent me a pair of their Heli jackets, I took it on myself to try and settle the question once and for all. And yep, thermometers were involved.

Read more: Down vs Synthetic with Arc’teryx Jackets

Alongside their range of thicker, winter-ready down jackets, Kathmandu’s Heli jackets are a lighter option suited to the shoulder seasons, city-use, or as a midlayer during the colder months. Most hikers will have seen (or worn) the flagship Heli Down Jacket, plumped up with a hearty sprinkling of 600-fill duck down feathers. However in more recent years, the Heli Insulated Jacket has entered the scene as a very respectable synthetic alternative. 

I’ve admittedly owned my fair share of both down and synthetic jackets across a number of brands, but in this case which one would I be packing?

Warm in my jacket and it makes me chuffed | @andrew.exploring

Kathmandu Heli Down Jacket v4

The Heli Down Jacket (now in its fourth iteration) is a great, compact option, highlighting duck down’s reputation for lightweight, effective insulation. Weighing in at a mere 340 grams (size medium) it’s certainly worth its weight in warmth, packing a surprising amount of loft into a garment you could pack down to (almost) fit in your pocket. For the feather nerds among you, we’re talking 600-loft down – putting it within the mid-weight range for warmth and affordability.

The jacket also features a cosy, fitted design and well-positioned zipper pockets.

Cosy pocket for my battered fingies | @andrew.exploring

Kathmandu Heli Insulated Hooded Jacket

The Heli Insulated Jacket leaves a few feathers for the ducks, instead using a synthetic alternative sporting the exciting name ‘Thermocore Ecodown’. More on exactly what this means later, but the jacket itself weighs in at 453 grams (again for a size medium) – 33% heavier for what looks to be a fairly similar jacket. To the touch, the Insulated Jacket feels a little more substantial, but otherwise utilises the same fitted proportions and zipper pockets. 

‘Yeah man it’s Heli insulated’ | @andrew.exploring

Heli Down Jacket v4 vs Heli Insulated Jacket

Performance

So let’s get down to business – how warm is each jacket keeping you? 

Contrary to the photos shown here (taken during a Queensland climbing trip a few weeks earlier), I took a more scientific approach one Saturday in July, and sat outside in the garden during an 11 degree morning with a kitchen thermometer. The goal? Running the numbers.

Insulating jackets function by warming the air between your skin and the garment, so all in the name of gear science, I sat out in the cold with the thermometer resting under my jacket for 8 minutes a-piece. And before anyone emails, there was no direct skin contact to interfere with the readings – the thermometer rested safely atop my T-shirt layer. Here’s what I found:

Interestingly, the synthetic insulated jacket proved warmer here. I’d peg this to the Insulated Jacket being generally heavier and thicker, and trapping a little more heat inside the jacket. However, remove 113g of its filling (bringing it to the same weight as the down jacket) and I’d expect the down jacket to have it beat. 

In general, the ‘down = warmer’ notion seems to hold up pound-for-pound. However my test here indicates that other factors (in particular, overall weight) also play a role. So don’t fixate on the feathers – where it’s cold and you’re able to afford a few extra grams of pack weight, an overall bulkier jacket is likely to still be warmer.

The jackets offer similar warmth, but the down is warmer for its weight | @andrew.exploring

Water Resistance

I reckon 80% of the duck down vs synthetic filling conversations I’ve heard inevitably end with the line ‘yeah, but if your down gets wet, it won’t work and you’ll be cold’. 

And this is true – when duck down gets soggy, the moisture collapses its loft (which is how it traps warmth and insulates you), largely rendering it ineffective. Synthetic materials, on the hand, tend to perform better when wet, and dry off quicker. For completeness, I dipped an arm of each jacket in water, and low and behold, after 10 minutes the synthetic covered arm felt warmer and more protected than the other.

In any case, Kathmandu has layered both jackets with a thin DWR (Durable Water Repellent) coating, lowering the odds of water permeating your jacket and wreaking havoc on whatever filling is inside. This isn’t a perfect solution, and a sufficient amount of rain will still get your jacket interior wet. So reading the forecast and packing accordingly remains your best bet.

Comfort and Design

As mentioned, the Heli Insulated Hooded Jacket is heavier and more cushioned. I personally like this in cold weather, particularly with the extra hood to lock in heat around your head. The down jacket feels thinner, which can be a positive where you’re looking to layer under other layers.

In terms of design, both jackets are otherwise very similar. They feature elasticated sleeve cuffs to keep your arms cosy, and an easy pack-down feature where the overall jacket tucks into an internal pocket for transportability. 

Lots of bright colours as well, which is always fun.

Also available in more muted colours if you can’t strike a pose like this | @andrew.exploring

Sustainability

Duck down isn’t everyone’s cup of tea. It’s taken from ducks already destined for the ‘big duck pond in the sky’ (by virtue of the meat industry), so make of that what you will. To their credit, Kathmandu ensures that all down used in its jackets is certified under the Responsible Down Standard (RDS), which means the feather comes from farms that uphold animal welfare protections and don’t do anything too horrible like live-plucking.

Where you’re still not down with that, the insulated jacket offers an easier-to-swallow option, using the Thermore Ecodown filling sourced entirely from recycled water bottles. There’s a video with exciting music you can watch if you’re still not convinced. 

Turns out plastic bottles can be pretty cosy | @andrew.exploring

Kathmandu is doing a lot of good things, including sustainability reports that take in Kathmandu, Oboz and Rip Curl, and certifications like bluesign, B Corp and Better Cotton. However consumer site Good On You has given them a score of ‘It’s a start’, which is basically the halfway mark. 

This seems a little harsh given the level of transparency going on, many brands have got this score while doing much less, but it sounds like Kathmandu could do more, especially with how it treats the workers creating its clothing.

Price

The price of each jacket is fairly aligned with what you expect to pay for a quality outdoors insulation layer (and quite a bit less if you snag it during a sale).

The Heli Down Jacket retails for $199.99 (commonly discounted to $99.99 or below), while the Heli Insulated Hooded Jacket starts at $219.99 (often lowered to $119.99). The hood costs $20 more on both models, regardless of whether they’re on sale. Nothing to break the bank, and unfortunately down jackets cheaper than this often present some dubious ethics.

About as cheap as a respectable down jacket gets | @andrew.exploring

Final Thoughts & The Winner

In the end, both jackets bring some real strengths to the table: the Kathmandu Heli Down Jacket v4 offers classic warmth with minimal pack weight, while the Heli Insulated Hooded Jacket delivers reliable wet-weather performance and a more sustainable fill. If you’re heading somewhere dry and want to travel light, the down version still gets my pick. But for damp conditions or where you’ve got a bit more pack weight to work with, the synthetic Heli is an excellent choice. Either way, Kathmandu has done well to make the decision a tough one.