Time-Saver Guide to Choosing a Synthetic Jacket

Posted by Mark Richardson on Dec 06, 2023

There are basically three types of synthetic insulation used in outdoor jackets:

  • 1. Sheet Insulation – Fibres are woven into a ‘mat’ structure and this is used to fill the jacket, this is the ‘traditional’ way of doing this and provides excellent warmth to weight and is pretty durable.
  • 2. Loose Fill Insulation – This is where synthetic fibres are ‘loose’, like down, and it seems they can trap more air and are therefore warmer than woven, but the jacket needs to have baffles to keep the insulation evenly distributed in the jacket, and baffles can cause cold spots. Some manufacturers attach the fibres to ‘strings’ to keep them in place without using baffles.
  • 3. Active Insulation – These are garments designed for energetic activities, sweat can pass through the insulation easily so you don’t get wet from the inside if you start powering up a hill. By definition, Active Insulation is not as warm as the other two because heat will be lost through the garment.

There are lots of insulation brand names, each with their own specific technology advantage but it's difficult to compare one against the other. There are a couple though that are common and have good reputations:

  • Polartec Alpha – in various formats is a well respected Active Insulation.
  • Primaloft – have been at the forefront of synthetic technology for years – they make all types to a high standard.
  • Octa – the latest Active insulation for exceptional wicking and breathability.

Our Summaries

“I want a jacket for 3 season backpacking to wear during the daytime if it gets cold”

  • You need the lightest possible because you won’t need too much insulation and you will be carrying it a lot of the time
  • Woven insulation excels at this, high warmth to weight ratio
  • Go for something less than 300g (Medium)
  • A windproof outer shell on the garment is a significant advantage

“I want a jacket for 3 season backpacking, I’ll be walking high level routes and expect to be wearing it most of the time”

  • Active insulation is the best option in this case, if you are wearing it most of the time it will have to cope with varied levels of exertion.
  • Jackets 300-350g (Medium) will suit most users but heavier ones are available and would be suited to colder conditions.

“I want a Synthetic jacket to wear around camp in the evening”

  • Loose Fill insulation excels here but Woven will also do the job
  • Depending on the environment and season you’ll be looking at 450grams plus (Medium)
  • Bear in mind you can double up, wearing your daytime insulation as well as this one.

“I want a general purpose Synthetic Jacket for day hiking and leisure use”

  • Weight is not necessarily an issue here; An Active piece will keep you comfortable but if you want a cosy warm jacket choose Loose Fill insulation which tends to look better as they have a quilted construction.

For a more in-depth discussion go to our full page on this subject…  Synthetic Insulation Explained

Our ‘Time Saver Guides’ aim to give you the benefit of our knowledge and experience in a concise format, some of what we include is our opinion because presenting all sides of an argument takes time!

Mark Richardson

Mark was the founder of Ultralight Outdoor Gear back in 2006 and has completed long distance backpacking routes in some of the remotest parts of the world. His favourite hikes have been Torres del Paine (full circuit), the John Muir trail and the Markha Valley trail (Ladakh, India). Although semi-retired Mark has not lost any enthusiasm for minimalist backpacking and is tackling Scotland’s Munros choosing multi-day backpacking routes over the more usual guide book excursions.

Read more from Mark Richardson