Down-Fill better than Synthetic Sleeping Bags?

Looking to buy a new sleeping bag? There are plenty of different brands, types, sizes, and stuffing types that you need to choose from.  One of the decisions is Down-fill better than a synthetic sleeping bag? 

Down Fill is better than Synthetic sleeping bags, for the reasons they are lightweight, keep you warmer and more durable than Synthetic. Even though Synthetic dry quicker a wet Synthetic bag is useless.

So now I have answered that question, let’s take a closer look at Down Fill Versus Synthetic Sleeping bags.

Downfill Vs Synthetic Insulation?

What are sleeping bags filled with? Sleeping bags are filled from two different types of insulation, Synthetic and Down Fill. Down Fill are feathers from geese and ducks

When it comes to performance Downfill and Synthetic insulation both have their pros and cons.

Choosing the right kind of insulation is important so you can turn challenging weather conditions into an enjoyable adventure.

Down Fill Insulation

Down Fill insulation is more expensive than Synthetic, its lighter and more compressible. It is also more durable and provides greater warmth.

Typically the high level of Downfill in a bag the more expensive the bag (visa versa).

Downfill is derived from soft feathers from the undercoat of geese or ducks.

How do the Down Rating work?

Fill Power is the universal rating system for the goose and duck down.

At first, it’s not the easiest measure to understand straight away, but once you do making the decision on your ideal down sleeping bag or jacket will be a lot easier.

So basically, the “fill power” represents the volume in cubic metric centimeters of a single gram of down, when fully lofted or fully fluffed up.

The higher the fill power, the more air a certain weight of the down can trap, and thus the more insulating ability the down will have.

Fill power ranges from about 300 for feathers to around 900 for the highest quality goose down.

The higher quality down (e.g. 900 fill) traps more insulating air pockets between the fine filaments than down of lower quality (e.g. 550 fill), and that’s why it expands to take up more space per gram.

Fill power is displayed in the form of a number, which you’ll normally find stitched somewhere on the outside of a down sleeping bag.

A note about ethical down: Most brands take steps to monitor the treatment of ducks and geese that provide down.

You can identify a bag from one of those manufacturers when you see it labeled as either RDS (Responsible Down Standard) or TDS (global Traceable Down Standard). To learn about what goes into those standards, read Animal Welfare and Outdoor Gear.

Synthetic Insulation

Synthetic insulation offers solid performance at an affordable price. Unlike down, it continues to insulate when wet, so it’s the bag of choice for damp climates. 

Downfill versus Synthetic

Insulation Type Key Benefit
Down Lightweight
Easy to compress
Excels in cold, dry conditions
Synthetic Quick-drying
Insulates when wet

Is Down warmer than Synthetic Insulation?

Yes, Down fill is warmer than Synthetic Insulation. Although Synthetic has been made to replicate Down, ounce for ounce, down is warmer than nearly all Synthetic insulations.

Generally speaking, very few man-made fibers can match down’s warmth-to-weight ratio

How are Sleeping Bags Temperatures rated?

In the past manufacturers test their sleeping bags using a variety of methods.

The sleeping bag industry solved this by agreeing to industry standards, however not all manufacturers use or rate their bags.

The EN (European Norm), was the original standard adopted by the sleeping bag industry.

Today, a new entity, the ISO (International Standards Organization), oversees bag testing, but the method is almost identical to the EN bag test. (Because ISO testing is so similar to EN testing, you can compare your old EN-rated bag to a newer bag that sports an ISO temperature rating when you shop.)

Image supplied by Sea to Summit

The standard measures 3 temperature ratings:

Comfort – the temperature at which a standard woman can expect to sleep comfortably, without feeling cold and in a relaxed position.

Lower Limit – the temperature at which a standard man inside the bag sleeping in a curled position is starting to feel cold but not shivering, this is the limit of performance for the sleeping bag.

Extreme – at this temperature anyone can expect to feel particularly cold and there is a risk of hypothermia. You should only use the sleeping bag in this range when it’s an emergency.

If you want to read more about the EN 13537 rating standards and validity, there is a paper from the Outdoor Industry which discusses in detail.

How do Sleeping Bags work?

A sleeping bag traps air and keeps it from circulating. This “dead air” around your body is warmed by the heat created by your body’s metabolism.

Remembering the bag forms a barrier between this air and the colder ground or outside air. Smaller spaces warm up faster and retain heat more efficiently.

Further Information

If you have enjoyed this review on Down Fill better than Synthetic Sleeping Bags? you will enjoy our other reviews.

Below are some of our other gear reviews and popular resources;

Best Backpacking Sleeping Pads

How to choose Backpacking Sleeping Bag

Best Women’s Backpacking Backpacks

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