Down Vs Synthetic Insulation
Insulation is crucial for staying warm and safe whilst hiking. But with so many options available, how do you decide which one is right for you? Is down or synthetic insulation the better choice? As with most things in life, both options have their merits, but perform differently depending on the conditions and your specific needs. Down is known for its excellent warmth-to-weight ratio and long lifespan, making it a top choice for many. On the other hand, synthetic insulation excels in moisture resistance, which is great for cold, rainy weather.
Below, we will share our experience with both options and discuss their pros and cons.
Down
Pros:
- Unrivalled warmth-to-weight ratio
- Smallest pack size
- Exceptional durability, more resilient to compressions
Cons:
- Less moisture resistance
- Slow drying time
- Requires baffles for use, as it’s not available in sheet form
- Expensive
Preferred products
- Timmermade SUL 1.5 Down Sweater (181g for a medium, ~$440)
- Montbell Superior Down Jacket (206g, $249.99)
- Montbell Plasma 1000 Alpine Down Parka
- Goosefeet Gear Custom Down Jacket (weight and price depend on customisation)
- Zpacks Goose Down Jacket
- Mont Zero Ultralight Down Jacket
- Cumulus Inverse
Discussion
Down is from the natural feathers of animals such as geese and ducks. Specifically, it is the soft and fluffy layer underneath their outer feathers. Since it is a natural material that is difficult to harvest and manufacture, down tends to be expensive.
Warmth from down is measured by fill power, which quantifies its lofting ability and capacity to trap heat. Higher fill power in sleeping bags and jackets means better loft and insulation efficiency.
The main advantage of down is its great warmth-to-weight ratio compared to synthetic insulation. It is generally lighter and retains more heat compared to the same weight in synthetic. Another benefit is that it packs into a smaller volume, making it highly portable. This is why we prefer down sleeping bags, as they compress well and take up less space in our packs.
It is important to note that whilst down packs smaller, it also retains its shape and loft even after repeated compressions. As such, we have found that it has a longer lifespan compared to synthetic insulation.
However, down does have some big cons. For one thing, down cannot be used as a solid sheet (unlike synthetic insulation). Instead, it must be filled inside baffles, which are sewn compartments in the fabric shell. If the baffles are too large, underfilled, or compromised by moisture or damage, the down can shift, creating uncomfortable cold spots.
Lastly, down is less moisture-resistant than synthetic materials, and it takes longer to dry. When it does get wet, down tends to clump and lose loft, reducing its insulating properties.
Synthetics
Pros:
- More resilient to moisture, making it ideal for active layers
- Can be made as a continuous sheet, minimising cold spots in lightweight garments
- Relatively cheap
Cons:
- Lower warmth-to-weight ratio
- Bulky when packed
- Less durable under repeated compressions
Preferred products
- Enlightened Equipment Torrid Jacket (235g, ~$314) and Pants (219g, ~$220)
- Cumulus Climalite Full Zip with Climashield Apex (345g, ~$312)
- Patagonia Nano-Air Light Hybrid Hoody (335g, ~$470)
Discussion
Synthetic insulation comes from man-made materials (typically polyester) designed to mimic the insulating properties of down feathers. The typical examples are Climashield APEX and PrimaLoft.
Whilst we have some favourite down jackets, for three season hiking we generally prefer breathable synthetic clothing, especially for our active layers. Synthetics are more moisture-resistant, quick-drying, and can retain insulation even when wet. These traits make them better at handling rain and sweat. Moreover, synthetics can be manufactured as a continuous sheet (e.g., Climashield APEX), which makes them ideal for lightweight garments. Unlike down, they don’t shift around, reducing the likelihood of cold spots.
The most significant drawbacks of synthetics are that they are more bulky and less resilient to compression. The more you compress synthetic insulation, the more loft it loses. Repeated compression can cause synthetic fibres to lose their insulating properties, lowering effectiveness over time.
Additionally, synthetic insulation is less warm per weight compared to down, only offering roughly the equivalent of 600 fill power (making it 2/3rds as warm as 900 fill power down). However, staying warm whilst moving is typically determined by your ability to manage moisture, rather than the overall warmth of your system. Our coldest hiking memories are in driving rain and strong winds between 0-5C. We find that high-quality synthetics are excellent at maintaining a comfortable temperature whilst moving for extended periods in those conditions.
As a final note, in super light garments (100g to 200g), we think that continuous filament synthetics like Climashield APEX come close to matching the warmth of down jackets because they don’t require baffling. Thus, they’re less prone to developing cold spots.
Conclusion
Both down and synthetic insulation offer distinct advantages. In general, for sleeping bags we prefer down for its superior warmth-to-weight ratio and compressibility. For clothing, synthetic insulation is our go-to because of how it performs whilst hiking in the rain. We generally don’t rely on our jackets for warmth in camp as that is what our sleeping bags are for!
Want to see which down and synthetic items we use? Check out some of our gear lists: