One question we get asked all the time is: what is the difference between synthetic and down insulated jackets?

The broad answer is that both insulation types have relative strengths, and it all boils down to the type of conditions you’re heading out in – and a little bit of personal preference.

Down Insulation

Down is a natural product that provides an unparalleled level of thermal efficiency; for a given weight, it’s extremely warm and offers increased compressibility. Down is ideal for colder, dry climates and lasts a long time. It can sometimes cost slightly more than synthetic options, but invest in down and it’ll serve you well for a long time.

You’ll often see ‘fill power’ detailed in our product information. This is the measure of thermal insulation the jacket provides.

Fill power typically ranges from 550 (medium fill power) to 900 (which is very high). This number represents the volume in cubic inches per ounce when fully lofted – so, in layman’s terms – when it’s fully ‘fluffed up’.

Essentially, the higher the fill power of a down jacket, the warmer it will be for its weight.

All of Rohan’s down products are certified to the Responsible Down Standard (RDS). The RDS upholds the welfare of geese and ducks that provide down and feathers for our high-quality insulation products. 

The ‘downside’ to down is that in damper conditions it can lose some of its loft and therefore effectiveness to retain warmth. However, some of our products, such as the Downtown Jacket, feature a highly effective hydrophobic treatment which dramatically increases the filling’s resistance to moisture. This ensures the jacket retains its loft and dries quicker.

Synthetic Insulated Jackets

Synthetic insulated jackets are filled with man-made fibres and perform well in the cold and in light rain conditions.

At Rohan we use Insuloft™ - our thermal insulation which has a better warmth-to-weight ratio than fleece, and better performance when wet than conventional down. It’s an advanced synthetic that’s tough, lightweight, packable, fast drying and easy to wash. Other examples include the Men’s Icepack Overhead and the Icepack Vest.

We also use Sustans® insulation which cleverly mimics the look and feel of natural down, but because it’s machine washable and quick drying, it’s more practical for everyday use. This insulation type is ‘denser’ than Insuloft™ and is filled into woven tunnels, instead of stitched channels, to retain the heat.

In summary, synthetic insulation replicates the warming effects of down and is an ideal option for more active outdoor pursuits where your body continues to produce its own heat. Plus, it’s slightly better at handling moisture than down so if you’re trekking to the top of a mountain in the UK, it’s perfect.

All wrapped up

Depending on the kinds of weather you frequently find yourself, and the types of adventures you’re heading on, rest assured, there’s something at Rohan. Here’s a quick guide to help you choose the most suitable insulated jacket…

·         For dry-cold conditions, choose our premium natural down garments.

·         For damp-cold conditions, go for Insuloft™, our advanced synthetic insulating wadding, or down-mimicking Sustans®.


  • Offers high levels of insulation in extreme conditions.
  • High loft.
  • Depending on fill power, can add bulk.
  • Reduced protection in showery conditions (unless hydrophobic treated).
  • Natural product means its long lasting.
  • Can be costlier.


  • Retains less water in wet conditions.
  • Low bulk, aiding packability.
  • Cheaper option to down.
  • Man-made fibres.
  • Lower fill power than down.
  • Less thermal protection than down.

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