Down vs Synthetic Sleeping Bags – How to Choose

If you’re thinking about investing in a new sleeping bag, then you’ve probably been researching like mad trying to figure out what is going to be the best bag for your future adventures.

One of the most important considerations when choosing a sleeping bag is the fill. This brings up the age-old question asked in the outdoor industry – which one should I choose? Down or synthetic?

What you decide will play a huge role in your comfort when sleeping outdoors. In this article, we’re going to break down everything you need to consider including price, compressibility, weight, durability, warmth to weight ratio, and maintenance so you can make the best choice when it comes to choosing the right gear.

Before you take the plunge, take a look at what we have to say below.

Man and woman lying in their Sea to Summit sleeping bags

It can be hard to decide which one will suit your adventures best. Image: Sea to Summit

What is down?

Down is the layer of light fluffy feathers found underneath feathers on ducks and geese.

Sea to Summit Down filling

Down is an incredible natural insulator. Image: Sea to Summit

What is synthetic fill?

Synthetic insulation is typically made of polyester fibres matted together to create sheets of fill. These sheets are then sewn into the bag in various ways to maximise loft.

View inside a sleeping bag with WaveLoft synthetic insulation

Synthetic insulation aims to mimic down to keep you warm. Image: Sea to Summit


Price is where synthetic and down also differ substantially. Down bags are quite pricey and will vary depending on the fill power, quality and weight. Producing synthetic fibres is cheaper compared with the growing and processing of down from birds.

This is why synthetic bags are generally very popular among beginners or those who don’t use their gear as much and can be several hundred dollars cheaper than a down sleeping bag.

Two people liying in MSR sleeping bags in a tent

You will have to spend more to purchase a down bag. Image: MSR

Warmth to weight ratio

There are many types of synthetic fill on the market from several leading brands, which can differ in quality and longevity.

Generally, they don’t provide as much warmth to weight ratio compared to down, but that’s not to say it’s not a viable option to keep you warm even on colder expeditions. The fill power or loft rating is how insulation is measured when it comes to down, with both terms being interchangeable. Put simply, a higher fill power indicates more warmth from less weight.

High-quality down is also lightweight and compressible which are qualities that are much needed for technical adventures. Despite all the technical advances in material technology, synthetic fibres have yet to be developed that match the structure and warmth to weight ratio of down.

3 different weights of down loft

The higher the loft, the better the insulation.

Cleaning, maintenance and storage

We would suggest that if you invest in a higher quality bag, then you should always use some sort of liner every time you sleep in it. That way, you will prevent the sweat, oils and dirt from building up, meaning you won’t need to wash it as much.

Down bags need to be washed using specialised down cleaner, as it’s designed to clean it and restore water repellency while retaining the loft of the down. For more information on how to wash a down bag, check out this guide here.

When not in use, down bags should be kept semi-lofted in their storage sacks that they came with, in a temperature-controlled space that’s cool and dry.

Synthetic bags can generally be washed in a large front-loader machine using warm water, a gentle cycle and very mild detergent. It’s also ideal to store them semi-lofted to avoid crushing the synthetic fibres.

Washing a down sleeping bag in a front loading washing machine

Synthetic and down have different care requirements. Image: Sea to Summit

Performance in wet conditions

Synthetic fill is known to loft and retain some of its warmth even if you douse it in water, so in a worst-case scenario, you would still have some comfort if your sleeping bag gets wet.

Down does lose its insulation properties when it gets wet. Lots of manufacturers now treat their down so that it absorbs less moisture, dries faster and retain loft better.

With these modern improvements, down is now more comparable to synthetic in terms of water-resistance.

Person sitting on sleeping bag and mat outdoors

Consider if you will be using your bag in wet conditions. Image: Sea to Summit 

Durability and longevity

A properly cared for down sleeping bag can last for many years before you start to see a deterioration in performance. You can compress it down into its bag over and over without it affecting the loft.

If used frequently, compressing a synthetic bag into its stuff sack repeatedly over a long period of time will eventually cause the fibres to break down.

Man lying in sleeping bag on a boat

If you take care of your down bag, it can last many years. Image: Sea to Summit


Down is extremely compressible, packing down to a compact and lightweight package that makes it ideal in the instance where space and weight are a premium.

You will be able to compress a synthetic sleeping bag well, but over time this will cause the fibres to break down, so eventually, the bag will lose its loft.

Man shaking Marmot hiking sleeping bag

The more compressible and compact, the better for lightweight adventures. Image: Marmot


You may only want to purchase down that has been responsibly sourced or may choose to avoid it entirely and choose synthetic if that’s your personal preference.

At the end of the day, there are a plethora of options available to you, so you’re bound to find the perfect sleeping bag that meets all your needs.

Symbol representing RDS certification

Look for down bags that are responsibly sourced. Image: Sea to Summit

Which one should I choose?

We’ve broken down the pros and cons of each one and laid out some suggestions for what style and type of bags are suited to different activities and needs.

  • Regular camping and occasional lightweight adventures

If you are planning on using your bag regularly, a down bag with a versatile tapered rectangular shape with a reasonable compact packed size is ideal. This way, you can get the maximum longevity and performance when camping, even on lighter trips.

Couple with their dog sitting in their sleeping bags on the back of a ute at the beach

A down bag with a streamlined shape will serve you well as an all-rounder. Image: Sea to Summit 

  • Occasional camping

A synthetic sleeping bag with a versatile temperature range is ideal for this kind of use.

Synthetic sleeping bag for camping

A quality synthetic bag is ideal for camping. Image: Darche

  • Kayaking and rafting camping

Go for a lightweight synthetic sleeping bag, as if it gets wet, you will still have some comfort.

  • Alpine conditions

Look for a sleeping bag with high-quality down, a water-resistant shell and a mummy shape so that it will keep as warm as possible when sleeping in alpine conditions.

Man sitting in Marmot sleeping bag in alpine conditions

When snow is on the cards, make sure you choose a suitable bag. Image: Marmot

Breakdown – Down vs Synthetic


  • Best warmth to weight ratio
  • More expensive
  • Longer lifespan
  • Loses insulation abilities when wet


  • More affordable
  • Will offer some comfort when wet
  • Dries faster
  • Heavier
  • Less compressible
  • Shorter product lifespan

Two sleeping bags laid out under the stars at night

There is a place for both types of bags for different uses. Image: Sea to Summit

It may sound like we’re favouring down bags here, but when you look at the stats and weigh up all the factors, they’re generally warmer, more compressible, and last you longer which makes them a good investment if you use it frequently.

However, if you’re an occasional adventurer, or are on a strict budget that doesn’t cover a down bag – then you can still get a high-quality synthetic bag that will suit your needs.


What kind of sleeping bag do you own? Do you own more than one?