How to choose a down jacket

When you’re heading out into the great outdoors, there’s nothing better than a down jacket to keep you protected against the cold. In this guide, we will look at how to find the best down jacket for your needs and answer some of the most common questions about fit, fill and durability.

Let’s get started!

What is a down jacket?

Down is a natural insulating later that’s found on ducks and geese, it helps keep their bodies warm when they’re swimming in cold water. Down jackets are insulated with these feathers to provide warmth and insulation, both duck and goose feathers are used in these jackets but goose is regarded as the warmest and lightest of the two.

The loft (fluffiness) of down acts as a great insulator and creates thousands of tiny air pockets to trap and retain heat. The more air that can be trapped between you and the cold air, the better you’re insulated and the warmer you will be. In terms of warmth-to-weight ratio, down is the best insulator around and is highly resistant to damage caused by compression – making it the perfect choice to pack in your kit bag!

What is down fill power?

When you’re searching for a down jacket you may come across the ‘fill power’ of the jacket. This rating is the measure of the loft of the down and how insulating it is. The higher the fill power rating, the more insulating the jacket is for its weight.

Fill Power Rating
400 – 450 Medium
500 – 550 Good
55 – 750 Very Good
750 – 900 Excellent

Fill power is calculated in laboratory conditions by measuring in cubic inches per ounce. An ounce of down is compressed in a glass cylinder and the ability to ‘bounce back’ and the loft is what gives us the fill power rating.

The fill power rating also gives an indication of the quality of the down used. The better quality down, the higher the fill power rating!

There is another figure that is typically associated with down jacket measurement, this is the percentage of down to the percentage of feathers. This is usually found in the jacket specifications as 90/10, for example. The higher the percentage of down to feather, the higher the fill power. Feathers do not produce that all-important loft, so the more feathers the lower the fill power and the less insulating the jacket will be.

Real vs Synthetic Insulation

There are synthetic insulation jackets on the market, however real down feathers are much lighter than their synthetic counterpart. Real down jackets offer excellent heat retention however, loses this insulating ability when wet, synthetic jackets have the benefit of retaining heat even when damp which can prove valuable when wearing in tough conditions. Although down jackets tend to be more expensive than synthetic versions, down tends to last longer if looked after, has a higher warmth to weight ratio and a smaller packed size for trips where space matters.

Concerns regarding how down is sourced have led to many brands, including Patagonia, using ‘traceable down’ or ‘certified responsibly sourced down’ to help address fears that their sources are unethical.

Sewn-through vs. Box Wall?

There are two main construction methods for down jackets: sewn-through and box wall. Let’s take a look at the benefits of each one!


Sewn-through down jackets are the most common type, and the easiest to construct. The outer material is stitched directly into the inner lining separating the down into different horizontal baffles. This method of jacket construction uses less fabric and is lighter than the baffled technique. Although most jacket manufacturers use this method, the drawback is that the sewn seams create potential cold spots in the jacket.

Box Wall

A horizontal box wall construction is the warmer option for those looking for a down jacket. This method utilises loft more efficiently, resulting in less cold spots where warmth escapes the jacket. The box wall compartments are designed to hold the down in place around the body to offer maximum performance. Jackets made using this method are typically heavier and do not pack as small as their sewn through counterparts.

How should a down jacket fit?

When buying a down jacket you need to ensure that you get a fit that’s not too tight, and not too loose. This can be hard to gauge so consider how many layers you will be wearing underneath the jacket on a typical trip and ensure that there’s not too much extra room for cold air to come in through the hem or arms.

Down jackets are quite bulky by nature so you need to make sure that you can move your arms freely when wearing it.

Look out for other features to enhance your jacket when searching for the perfect one. Cuffed wrists and waist details can help retain warmth and padded pockets will ensure your hands are never cold on a chilly day! A hood will also help add extra warmth but could impact the weight of your jacket.

If you’re looking for a new down jacket, you’re in luck! At World Backpacker we offer a wide range of down jackets for men and women from top performance brands such as Berghaus and Marmot. Each brand brings innovative technology to the table, with striking designs that are built to last.

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