Which is Better: A Down vs Synthetic Sleeping Bag?

Which is Better: A Down vs Synthetic Sleeping Bag

Ah, the age-old question pondered by campers worldwide. Deciding between down vs synthetic insulation is one of the most frequent choices backpackers face. Sleeping bag insulation can make or break a trip. It's hard to get a good night's sleep when you're cold and it's hard to enjoy your journey when you don't sleep well.

Choosing between a synthetic sleeping bag and a down one is a tough choice. Each has its pros and cons. Careful consideration and research should go into your decision. And, just because your pal swears by his synthetic bag doesn't mean it's the right choice for you (and vice versa).

Purchasing the perfect sleeping bag can feel daunting. We want to help you choose the right one for your needs. This guide should help you feel more at ease about your final decision. It covers the pros and cons of both down and synthetic fill, the best environments for each, what to know about fill power, and more.

Down Insulation

Highlights of Down Insulation

  • Compressible
  • Lightweight 
  • Durable
  • Better warmth-to-weight ratio

Down sleeping bags can be easily compressed into a stuff sack. Much more so than synthetic sleeping bags. Between that and their light weight, it's easy to see why down sleeping bags are favored amongst backpackers.

Its warmth-to-weight ratio is unbeatable too. It takes much less down than synthetic material to fill the same area because it lofts more. And it insulates better due to its structure of fine, branched filaments. This is also why down bags are so light compared to synthetic ones. While advances are being made in the world of synthetic materials, there are still none that compare to the insulating properties of down.

With proper care, down is also much more likely to keep you warm for years to come. Decades, even! So, if you're looking to keep the same bag for a while, you can't beat down. It's a worthwhile investment.

Thermodown Down-Filled Sleeping Bags by Paria Outdoor Products

Drawbacks of Down Insulation

  • Expensive
  • Does not insulate once wet
  • Compressed parts can create chilly spots

The biggest drawback of down is its inability to insulate once it gets wet. This can create issues if you frequent rainy or damp areas. This is especially true if you prefer tarp camping and get caught in heavy rain. For dry, cold conditions, many hikers still prefer down.

Body oils can also seep into your bag over time if not properly cared for. This also causes feathers to clump up, just like outside moisture. The air pockets between the down provide much of its insulation. These diminish when wet, leading to a decline in insulation power.

Some manufacturers now use Durable Water Repellent (DWR) down to offer some water resistance. This is also known as hydrophobic down. Basically, the down is treated with a water-resistant coating. This enables the down to repel water and prevents it from clumping. While it does help some, it still won't match the insulating quality synthetic is capable of when wet.

Regular down sleeping bags can already be quite pricy. The DWR ones run even higher. There is a frugal way to make your down bag more waterproof. Many backpackers use Nikwax Down Proof to add a layer of protection. This takes a simple wash-in application. There is also a spray-on version that is perfect for spot applications. For example, you might only want to spray the foot box of your sleeping bag since that is the most common spot to get wet.

Speaking again of price, this can also cause some people to balk at down bags. Unfortunately, since it is not easily made in a factory, like the polyester fibers used in synthetic bags, it raises the price. But, more and more economical options are becoming available.

Another downfall of down is that compressed areas can create cold spots. The best way to deal with these is by having another insulating layer. Most people use a foam pad or inflatable sleeping pad.

What is Fill Power?

You will likely come across this term when researching down sleeping bags. And if this is new territory, it can be confusing.

Fill power is the measurement taken in labs to determine how much loft down has. This also determines how well it can trap heat. The measurement shows how many cubic inches it takes one ounce of down to fill. Therefore, 800 fill power down fills 800 cubic inches of space with one ounce.

Fill power ratings usually range between 600 and 800. The higher the number, the better. These provide better insulation and loft. Plus, they compress better too. 

Duck or Goose Down?

Traditionally, sleeping bag manufacturers have used goose down. However, you may notice that duck down is also becoming more popular. While it may be less expensive, it comes at a cost. Duck down does not insulate as well as goose. Some primo goose down can reach a 900+ fill power. Duck doesn't range higher than 800, at best. However, at the same fill power, both duck and goose provide very similar performance. Since duck is cheaper than goose, it provides a great value.

Final Thoughts on Down Insulation

Contrary to popular belief, cleaning a down bag is pretty similar to that of a synthetic one. Just make sure you use a gentle detergent and/or one made specifically for down. Never dry clean your sleeping bag, since the chemicals can cause permanent damage to the down fill. And, of course, always follow the manufacturer's care instructions.

While down tends to hold up better to being compressed, it's also recommended to let it “hang loose” when possible. This will lengthen the life of your bag.

Thermodown 15 Sleeping Bag

When storing down sleeping bags, either hang them or use a mesh storage sack to keep the down as uncompressed as possible. This will ensure that you down sleeping bag lasts for decades.

Since down is so lightweight and compresses well compared to synthetic sleeping bags, it's easy to see why its the top choice amongst many backpackers. Unless you're in exceptionally wet conditions, down is a great choice for most climates.

Synthetic Insulation

Highlights of Synthetic Insulation

  • Still insulates when wet
  • Dries quickly
  • Less expensive

One of the major perks of synthetic sleeping bags is the fact that they are still able to insulate when wet. Obviously, if it's very damp or soaked it won't matter what material a bag is made of. You'll have a bad, cold time either way. But, wet synthetic bags will still provide you more warmth than a wet down one. (Unless, of course, it's made of hydrophobic down or has been treated with a water repellent.)

Synthetic bags also dry much quicker than down ones. This can get you packed up or into a warmer sleeping arrangement sooner if your bag has gotten wet along the way. It's also nice to shave some time off of the cleaning process at home.

For a lot of people, the price tags of synthetics are irresistible. In general, they are much less expensive than down bags. Again, their “fluff” can be easily produced in a factory. 

Drawbacks of Synthetic Insulation

  • Less compressible
  • Much heavier than down
  • Less durable

Unfortunately, synthetic bags do not compress nearly as well as down counterparts. This is due to the construction of its fibers. Again, you need more synthetic material to fill the same space compared to down. This makes most synthetic bags heavier and stiffer. They can be a bear trying to get back into a stuff sack. 

Synthetic fibers also tend to break down faster over time. Therefore, they are not as durable as down bags. Leaving a synthetic bag compressed for long periods can also negatively affect its longevity. You should expect a synthetic bag to see deterioration within 5-7 years.

Continuous Filament or Short Staple?

When researching synthetic bags, you might also want to check whether it's made with continuous filament or short staple. In a nutshell, continuous filament is made of long strands of varying widths weaved together. This provides high loft and durability. They also prevent cold spots from forming. However, they tend to be bulkier and not easily compressed. Short staple is more like down. They are made of densely packed short filaments. These bags are more flexible and compress well. The trade-off is they break down quicker. 

Final Thoughts on Synthetic Insulation

If you're looking for the best of both worlds, some companies offer sleeping bags made from varying percentages of both synthetic materials and down. These can be an economical option for those wanting a down bag without the high price tag. Keep in mind that no synthetic material out there compares to the qualities of down, though. 

Synthetic sleeping bags can be a good option for those starting out car camping or even backpacking. More than likely, you don't want to spend a ton at first if you're not sure you will like it. (Whether it's the bag itself or the activity!) Car campers don't need to worry as much about weight, which is another reason synthetic is a feasible option. They also work well in warm weather when you don't need as much thickness and insulation. 

Synthetic Insulation for Car Camping

Synthetic insulation is perfect for car camping, since it's much cheaper and weight/packed size are not as important. (Image source: Unsplash)

Other Factors to Consider 

Keep in mind the size/shape of the bag. One that is closer to your shape/length will keep you better insulated regardless of fill type. Mummy-style sleeping bags will keep you the warmest. Traditional, rectangular-shaped sleeping bags give side sleepers and those who toss and turn a lot more wiggle room. But, they won't keep you as warm due to the extra space in the foot box.

It is up to you to weigh the pros and cons for your own individual needs. If you are reading this, it is likely that you already have some personal preferences in mind when it comes to sleeping bag size and shape. There are plenty of bags on the market nowadays that you are sure to find the style and fill you are looking for. 

Also, be sure to select the appropriate temperature rating. Neither down or synthetic insulation will be able to keep your warm if there's just not enough of it for the temperatures that you're experiencing. On the flip side, using a sleeping bag rated for very cold temperatures during the summer season is unnecessary and can be very hot and uncomfortable. In that case, you might consider a sleeping quilt instead.

Paria Outdoor Products Thermodown 0 Sleeping Bag

0-degree sleeping bag will definitely keep you warm during late fall, winter, and early spring backpacking trips. However, it might be too warm and too heavy to use during the summer.

Ready to consider down for your next purchase? Check out our affordable down sleeping bags and versatile down quilts.

Shop Backpacking Quilts
Shop Down Sleeping Bags

You can find detailed information on sleeping bag care in our FAQ. If you have any questions, feel free to leave us a comment below or email us directly.

Read Next

For more great backpacking info, check out our comprehensive backpacking articles that cover just about everything there is to know. If you're just starting out, our Backpacking 101 section covers all the basics. Some popular topics include:

How to Choose a Backpack
How to Select the Ideal Backcountry Campsite
Tips for Hiking in the Rain
How to Handle Emergencies on the Trail
Keeping Insects and Pests Away on the Trail

Expert backpackers can find more advanced topics covered in our Expert Articles.

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