Insulated Puffy Jackets – Down v. Synthetic
A warm, puffy jacket is required equipment for backcountry skiing (read our backcountry ski packing list). It’s your ticket to comfortable transitions, warm summit breaks and lightweight insurance for staying warm in the case of an emergency.
I usually carry two insulated jackets in my backcountry ski pack—one light-to-midweight synthetic puffy jacket (that gets worn a lot) and one warmer down jacket (that gets worn occasionally). The synthetic puffy serves as my go-to for short breaks and as a mid-layer that I wear when touring in cold conditions. The down jacket is my backup warm layer. It’s the jacket I put on for extended breaks if I’ve gotten cold and wet or when I need extra warmth to deal with an unforeseen delay.
What are the most significant differences between down and synthetic insulation? What’s the best insulated jacket for you? Read on . . .
Down Insulation
While synthetic insulation has made significant gains in recent years, down insulation is the undisputed winner of the warmth-to-weight ratio competition. This means that ounce-for-ounce down is the warmest insulation option available.
For the uninitiated, down insulation is made from the soft, fluffy undercoat of ducks and geese. It creates high-loft clusters that trap air and body heat to keep you warm. Down is exceptionally light, compressible and known for having a long lifespan when well maintained. But down has its limitations: It’s not very breathable. It loses its loft and insulation value when wet, and it’s not cheap. Plus, not all down offers the same warmth. Depending on its sourcing, down insulation is not always the most environmentally responsible insulation choice.
What Does the Down Fill Number Mean?
The warmth of down varies by fill rating or fill power—like 600-fill or 800-fill. The fill power number reflects the amount of down inside a given jacket. Fill power is calculated by placing one ounce of down in a graduated cylinder and measuring the volume it occupies in cubic inches. The higher the fill power number, the warmer the jacket. 800-fill is a standard benchmark for defining a high-quality down jacket, but higher fill power ratings exist.
When to Use Down Insulation
As described above, down insulation offers the highest warmth-to-weight ratio, which means ounce for ounce; it’s warmer and lighter than synthetic insulation. Along with being lighter, down is also more compressible than synthetics. In other words, a down jacket is warmer, lighter and more packable than a similarly filled and weighted synthetic jacket. Anytime weight, packability and warmth are top priorities, the best option is a down jacket.
While down is not warm when wet, advances in waterproof treatments are making down more viable in damp conditions. However, water-resistant down is designed for short-term water exposure, not prolonged wet conditions.
If warmth is what you are after, check out the Arcteryx Thorium Jacket, the Outdoor Research Helium Down jacket or the Patagonia AlpLoft Down Jacket.
Down Insulation Pros
- Best warmth-to-weight ratio
- Lightweight
- Packable
- Best for stationary warmth—base camp use, breaks, non-aerobic activity
Down Insulation Cons
- Limited breathability
- Loses loft and warmth when wet
- Higher maintenance to clean
Synthetic Insulation
Synthetic insulation comes in a wide range of variations, and it’s generally made of polyester fibers of one form or another designed to replicate the qualities of down. While synthetic insulation can’t match the loft, warmth and packability of down, it does have its benefits. It can be less expensive, more breathable and retains its loft (warmth) when wet. Some new synthetic insulations are getting remarkably close to the warmth-to-weight ratio of down, namely Patagonia Plumafill. 
For backcountry skiing, the most significant benefits of synthetics over down are breathability and wet weather performance—the off-and-on wear of a puffy means it gets worn, packed, worn again and packed again. The act of wearing and repacking is hard on down if the jacket is getting damp between uses. Synthetic insulation holds up well to packing and repacking through a ski tour.
Synthetic insulation’s combo of breathability and weather resistance makes a synthetic puffy more versatile than down as you can wear it while active versus just as a warm layer when stopped.
Unfortunately, synthetic puffys don’t have fill ratings that offer direct comparisons to the fill power of down, which makes it difficult to compare the warmth of one jacket to another.
When to Use Synthetic Insulation
Synthetics are the best choice when you need breathable warmth and midweight warmth that you can layer under or over other layers while skiing and climbing.
Given its wet weather performance and breathability, synthetic insulation is more versatile than down insulation. It’s easy to wash and generally more affordable. Given the focus on recycled polyester, synthetic insulation is more sustainable and humane than down.
As the introduction mentions, synthetic insulation breathes better than down. I recommend synthetics for mid-layer warmth and days when you need a jacket you can wear moving uphill and down or under your shell.
If a versatile jacket is what you are after, synthetic insulation is the best choice. Check out the Arcteryx Atom LT, and the Patagonia Nano Air or Micro Puff. For an extra-warm and still very packable synthetic insulated jacket, the Arcteryx Rush Insulated Jacket packs serious warmth and comfort into a nice stuffable design.
Synthetic Insulation Pros
- Breathability
- Warm when wet
- Easy care
- Best for active days and layering—breaking trail, working outside, aerobic activity
Synthetic Insulation Cons
- Limited compressibility
- Heavier and bulkier than down for the same level of warmth
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