Picture yourself huddled in your tent with the wind whipping outside the thin layer of nylon that separates you from the elements. If you choose the wrong gear for that situation, you’re in for an uncomfortable or even potentially dangerous night.
Down fill is an essential part of the outdoor gear industry because it provides warmth with minimal weight. Learning how down fill power and weight create warmth enables you to better comprehend the functionality of things like down jackets, sleeping bags, hats, and even booties.
So when you’re in that hairy, aforementioned situation, having gear that uses down could probably save your life or at least make for a much more comfortable experience.
Whether you’re climbing snowy peaks, camping in cold climates, or strolling through chilly city streets, down is still one of the warmest materials available. And it still provides an incredible warmth-to-weight ratio. Let’s break down what else you need to know about down power and fill weight and how to prepare for your next cold-weather adventure.
How Down Insulation Works
If you’ve ever seen ducks or geese swimming in nearly-frozen ponds in February, you’ve probably wondered how they manage to stay alive. The simple answer is: feathers. Down insulation is made out of the same feathered insulation that geese and ducks use to keep themselves warm when it counts the most.
Humans generally use the soft underbelly of the feather, which is stripped of the tough feather particles before being placed in a containing material like nylon. The down then clusters together to trap air, creating pockets of warmth that you create from the heat of your own body.
The way in which the down clusters and the quality of the air pockets it creates directly influences its down power or “loft”. Without getting into too much detail (we’ll do this later), higher loft means more air is trapped, leading to greater warmth and lighter, more compressible products.
In short, the less loft or down power, the less insulated or warm something is.
Outdoor gear is constantly changing, yet the first recorded use of down feathers as insulation was in the late 1800s. It was then when most accounts suggest the first “sleeping bag” was designed. This shift in efficiency forever changed the way that we travel while camping and backpacking.
The less loft or down power, the less insulated or warm something is.
Types of Down Fill
If you’re new to the world of sleeping bags and jackets, learning how to tell the difference between all the different insulation types can be really overwhelming. Fortunately, there are just two types of down that are commonly found in sleeping bags and jackets today: goose and duck down.
Duck Down
This insulator has a slightly lower loft, meaning it traps less heat, than goose down. It also weighs a little bit more (and by a little bit, we mean fractions of an ounce per gram). But duck down is also less expensive, which can make it a really good pick for the budget-conscious hiker who wants a reliable sleeping bag or jacket without the hefty price tag.
The reality is that most well-made down products are still extremely lightweight and efficient in the backcountry. If you went the budget-friendly option and chose duck down, you just might end up carrying an extra half-pound compared to a lighter option.
Goose Down
This type of down is generally considered a premium material (yes, that means a little more costly). Yet it comes with a higher loft than duck down – i.e. it traps more heat – and is ultra lightweight.
Both duck and goose down lead the industry when it comes down to providing hikers and backpackers with lightweight gear that goes the extra mile to keep you warm. This is one reason why you’ll almost always find cold-weather athletes carrying some type of down sleeping bag and jacket. Keep in mind that some brands mix duck and goose down to provide a middle-of-the-road piece of gear at a mid-range price.
What is Down Fill Power?
Remember how we briefly talked about loft in the last section? Loft, also referred to as down power, basically indicates how much heat the down will trap around your body.
In layman’s terms, loft is like the “fluffiness” of down, and the fluffier it is, the better it can insulate. This means the higher the loft, the warmer the down, although the measurement is technically an indicator of how much room an ounce of down takes up in a cubic inch.
Down Fill Ratings Explained
If higher down indicates how much heat down will trap around your body, then the higher the “fill power,” the warmer the down.
Fill power ratings generally range from 400 to 900. Again, the higher the fill power, the higher the quality of the down.
Current industry standards bracket fill power this way:
- 400-500 Fill Power: This range of fill power is going to be moderately warm, and appropriate for summer and some shoulder-season adventures. It’s the most affordable option and is generally found in lifestyle or every day jackets.
- 600-700 Fill Power: This is a mid-weight fill power which means that it’s usually ideal for 3-season adventures and outdoor environments. The cost of this type of fill is mid-range, and the performance is reliable.
- 800-900 Fill Power: A premium category of down, 800-900 fill power is about as good as it gets. This type of fill can be found in highly technical equipment like alpine climbing and ultralight gear. As a premium category, it also generally comes with a higher price tag, but the performance usually makes it worth the cost.
What Is Down Fill Power Temperature Rating?
While fill power describes a measurement that alludes to the efficiency of down material, it doesn’t necessarily help you to determine how warm a piece of gear is going to be. Instead, warmth is a function of fill power and fill weight (or the amount of down that’s used in a product). A higher fill power simply means that a jacket will keep you warmer than a lesser-quality down for less weight.
Sleeping Bag Lab Ratings
One measurement that you can evaluate when choosing a sleeping bag is the EN or ISO rating. These ratings refer to lab testing measurements that were performed to measure the ability of a sleeping bag to retain warmth. As a result, many sleeping bags come with ratings that tell you the sleeping bag’s “survival” limits, as well as “comfort limits”.
While these measurements are still widely available today, they’re only estimates, and they don’t take personal preference into account. Furthermore, a sleeping bag that doesn’t feature this rating may still perform well or even better than the EN or ISO standards. They simply haven’t undergone the same tests.
What is Down Fill Weight?
Every backpacker and hiker loves down because it’s naturally insulative, it’s cozy, it’s lightweight, and it can easily be compressed, which makes it pack-friendly. But understanding down fill weight can help you to better understand how to leverage the material to support your outdoor goals.
Down fill weight is the total quantity of down used in a product, usually described in ounces or grams. An 8-ounce jacket of 800 fill power down is warmer than an 8-ounce jacket of 600 fill power down, for example.
Does Down Fill Weight Matter More Than Power?
Warmth is a function of fill power and fill weight...both are crucial in the calculation
Both fill power and fill weight are crucial in the calculation of warmth. Fill power determines how well the down traps heat and how much it can be compressed. Fill weight dictates how warm a sleeping bag or jacket will be.
For example, most extreme-weather athletes, like mountaineers, carry the lightest gear with the highest down fill power (for compressibility and lightweight structure). This could look like a 900 fill power goose down sleeping bag with a large fill weight.
Athletes who are looking for a mid-grade option might snag a 700 fill power sleeping bag with a mid-grade fill weight. And car campers might snag a sleeping bag with a 500 fill power and minimal fill weight.
Finding a warm system that combines both fill weight and down power is the best way to ensure that you’re warm and comfortable on all of your adventures.
Some Our Favorite Down Jackets and Sleeping Bags
Once you have an understanding of fill power, fill weight, and the way these components work together to create warmth, it’s a lot easier to look at adventure equipment and determine how warm an item might be. But then you still have to evaluate style, fit, and structure to set yourself up for success. A few of our favorite time-tested down jackets and sleeping bags include:
Exped Ultra -20 Degree Sleeping Bag
It’s easy to assume that a sleeping bag with a really warm design is going to be heavy. Yet Exped proves that this is not always the case. The -20 Degree Ultra Sleeping Bag weighs just 48 (3 pounds) ounces in a regular version, which is the same weight of some 10 or even 20-degree bags.
The standard version of the bag comes with a 32.7-ounce fill weight structure and 850+ fill power European goose down, which is about as good as it gets. While Big Agnes makes a phenomenal 0-degree bag with a similar weight, its temperature is less efficient by 20 degrees, for comparison.
Sea to Summit Spark 15-degree Sleeping Bag
Another option for slightly warmer conditions is the Sea to Summit Spark 15-degree Sleeping bag. This sleeping bag is designed for women (which really means that it’s a little bit more generous in warmth and a touch smaller in height than non-gendered bags). It weighs just over two pounds. It comes with 850+ fill power goose down and adheres to Nemo’s sustainable practices, making it a great ethical option.
Outdoor Research Helium Down Hoodie
Summertime adventures don’t require the same intense gear that arctic and alpine adventures typically require. But you still want your equipment to be durable, lightweight, and comfortable like the Outdoor Research Helium Down Hoodie. This jacket is extra light, weighing 15.4 ounces. It’s made with 800 fill power goose down that’s ethically sourced. And the external 30 denier ripstop nylon does a great job of battling rogue branches and rocks.
Fjallraven Expedition Pack Down Hoodie
A nice mid-grade down jacket is the Fjallraven Expedition Pack Down Hoodie, which weighs less than a pound and is designed for “polar” hiking conditions. This jacket comes with 90% 700 fill power goose down and 10% feather to make a warm and comfortable adventure companion. But it is a little less packable than the Outdoor Research Helium Down Hoodie.
Arc’teryx Cerium Insulated Hoodie
On the high end of most athletes’ budgets is the Arc’teryx Cerium Insulated Hoodie, which retails at $400 but comes with 850 fill power European white goose down. This jacket is easily the lightest option on the list, weighing 10.2 ounces. It also uses mapping technology to pack extra heat in cold-sensitive areas. The result is a jacket that does more than most of its competitors.
Care of Your Down Gear
A high-quality sleeping bag will last most people at least a decade of vigorous use. Those who are moderately active can likely get even more use out of it, but an essential part of the longevity process is in the way you care for it.
Most sleeping bag manufacturers have their own guidelines when it comes to the washing and drying of their sleeping bags. Generally, they suggest using a down-specific detergent like Nickwax to avoid damaging the down. You can then hang dry or potentially dry your bag on low. Store your bag decompressed in a loose bag.
Tips and Tricks for Using Down Products
Keeping your down fresh is one good way to ensure the longevity of your gear. Here are a few additional tips and tricks to keep you poised and ready for your next adventure:
- Wash your down gear about once per year. This helps it to retain loft, which contributes to better efficiency.
- When drying your sleeping bag in a dryer, toss a few tennis balls into the dryer to help break up wet clumps of down.
- When hiking in wetter climates, wear an outer, water-proof layer over your down. Down loses its insulating properties when wet and takes much longer to dry than synthetics.
- Whenever possible, keep your down gear items uncompressed. Inevitably, backpacking and camping will involve some amount of compression. But when you get to your campsite, leave those items in your tent instead of stuffed in a bag.
- Pack a sleeping bag liner to protect your sleeping bag from oils and stains. It’s a lot easier to wash a liner than it is to wash a sleeping bag. These can be found in silk, cotton, and flannel options. Generally, silk is the most lightweight option, and it has natural antimicrobial properties to keep the funk at bay.
