Down vs. Synthetic: How to Choose Your Sleeping Bag

Sleeping Bag: An ultralight down sleeping bag on the grassy mountaintop, with a scenic mountain view

In this post, we'll take a look at:

Choosing the right sleeping bag is important. It determines how heavy your backpack will be and how warm you’ll stay in different weather conditions. 

In this post, we’ll be looking at the two most popular insulation options: down and synthetic. We’ll discuss the differences between them, covering the pros and cons of each type. By the end, you’ll have the information needed to choose the perfect sleeping bag for your needs.

Interested? Let’s get started.

Key Takeaways

  • Down insulation has an excellent warmth-to-weight ratio and compressibility, but it is vulnerable to moisture and requires special care.
  • Synthetic insulation retains some warmth when wet and dries quickly, but it is heavier and less compressible than down.
  • Consider your budget, intended use, and preference for weight vs. performance in damp conditions when choosing between down and synthetic insulation.

Understanding Insulation

When it comes to sleeping bags, ‘insulation‘ is key.

But why is insulation so crucial when picking a sleeping bag? Well, the type of insulation in your bag affects its weight, warmth, and even how well it handles moisture (like rain or sweat).

In the next sections, we’ll explore two common types of insulation for sleeping bags: down and synthetic.

Down Insulation

Let’s talk about ‘down’ insulation. It’s not feathers, even though it comes from birds. Down is the fluffy stuff found underneath the outer feathers of ducks and geese.

You might have heard of goose down, but there’s also duck down:

  • Goose down is top-notch and can be super fluffy.
  • Duck down is good too, though it might not fluff up as much.

The good news is, they both work well, and you’ll often find duck down sleeping bags that are more budget-friendly.

If you’re interested in delving deep into down details, we suggest checking out this forum topic here.

Pros of Down Insulation:

  • Excellent compressibility: One of the great things about down is how easily it compresses into a small bag. Plus, they’re ultralight, so you won’t be lugging around a heavy load on your adventures.
  • Impressive warmth-to-weight ratio: Down excels when it comes to warmth compared to its weight. It’s like having a super warm blanket that’s as light as a feather (literally).
  • Long-lasting with proper care: With proper care, down sleeping bags can last for years – even decades.

Cons of Down Insulation:

  • Vulnerable to moisture: Down’s weak point? Water. It doesn’t handle moisture well, losing fluffiness and warmth when wet. But fear not, some down is treated to resist small amounts of moisture.
  • Requires special care to maintain fluffiness: When you’re not out on an adventure, it’s a good idea to store your down sleeping bag in a way that lets it “breathe.” You can hang it up or use a mesh storage sack to keep it uncompressed.
  • Can be expensive, especially with higher fill power: Fill power is a rating for down insulation, and higher fill power means a lighter bag with the same warmth. However, it often means a higher price tag.

Synthetic Insulation

Now, let’s shift our focus to ‘synthetic’ insulation. It’s another important player in the sleeping bag world, and it has its own set of perks and quirks.

Pros of Synthetic Insulation:

  • Still provides insulation when wet: One of the standout features of synthetic insulation is its ability to keep you warm even when it’s wet. While no insulation is a fan of being soaked, synthetics handle moisture better than down.
  • Dries quickly if it gets wet: Synthetic sleeping bags also have a speedy side – they dry fast. If your bag gets wet, whether from rain or sweat, it won’t take forever to get it back in action.
  • Generally more budget-friendly compared to down: For those of us watching our wallets, synthetic sleeping bags can be a savior. They tend to be less expensive than down bags because they are easier to produce in factories.

Cons of Synthetic Insulation:

  • Less compressible than down: Unlike down, synthetic insulation doesn’t compress as well. This means it takes up more room in your backpack, leaving you with less space for other essentials.
  • Heavier than down: Synthetic insulation is typically 20% heavier than down for the same level of warmth, which can make your backpack weigh more.
  • Less durable than down: Synthetic insulation is generally less durable than down, and it may wear out more quickly over time.

Down vs. Synthetic: Making the Choice

Sleeping Bag: An ultralight synthetic sleeping bag next to a campfire on a hill during the evening

Now comes the exciting part – deciding between down and synthetic insulation for your sleeping bag.

Consider your own needs and preferences. Recall the pros and cons of both down and synthetic insulation that we’ve discussed. Take a moment to weigh these factors against your priorities.

You should choose a synthetic bag if…

  • You are willing to trade off some weight for a more budget-friendly option.
  • Looking to stay completely warm in damp conditions.

You should choose a down bag if…

  • You appreciate the ultimate warmth that comes at a slightly higher price.
  • Want to keep your backpack as light as possible.

Final Thoughts

The key to choosing the right insulation is making an informed decision. Take your time to research, consider your specific camping conditions, and factor in your budget.

Remember that there’s no one-size-fits-all answer; the best choice for you might not be the same for someone else.

Looking for an ultralight sleeping bag? Check out our TOP 5 guides that list the lightest options on the planet.


Is down sleeping bag worth it?

A down sleeping bag is worth it for its ultralight weight, warmth, and durability, and the fact that some can pack down as small as a soda can. However, it may not be ideal for very wet conditions.

Is 600 or 800 down warmer?

While 800-fill down is technically warmer for the same weight, the design and construction of the sleeping bag or jacket also play a significant role. Additionally, personal preferences and the specific conditions you’ll encounter matter. In extreme cold, 800-fill down may provide a slight advantage, but 600-fill down can still offer excellent warmth. Consider factors like the bag’s design, your insulation needs, and the intended use to make the best choice.

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Leading the pack is our editor-in-chief, Alex Jardine – an ultralight evangelist who's hiked over 10,000 trail miles across the globe. He's basically a walking outdoor encyclopedia. This dude loves testing out the latest and greatest products, so you can trust his recommendations are always well-informed and reliable.

We treat all our suggestions like advice from close trail buddies. No fluff, just real insights from folks who live and breathe the outdoor life.

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