The power of the puffer has been put to the test by Fair Go – looking at which brands will keep you warmest this winter.

Puffer jackets are either filled with synthetic materials, or with 'down' - that's the soft, heat-trapping fluff beneath a goose's feathers

The warmth of a down jacket comes from a combination of the quality of the material it's filled with and the quantity that’s put in – this is known as 'loft' or 'fill power'.

While there are a range of jackets on the market suited to different activities, climates and weather conditions; Fair Go picked out four entry-level puffers to put to the test.

All were the same size jackets, without hoods, two of them were down jackets from Kathmandu and Macpac with the same 600 loft value and two were synthetic puffers from Cotton On and Glassons, filled with recycled polyester.

While the jackets can often be found on special, at full price, they retailed for:

Fair Go’s tests warmth tests were done by Professor Mohammed Farid of Auckland University, who’s an expert in thermal engineering.

He tested the jackets in controlled laboratory conditions, with a special system his team had built, which generates heat similar to a human body.

But although Glassons won the warming award, it was also the thickest and heaviest, by 300 grams.

Farid explains that "there is a compromise between the weight of the jacket and its ability to insulate the body".

Meaning some jackets may have good insulating capability, but can be heavy and therefore, less convenient."

The Macpac was the lightest, just 490 grams, Kathmandu slightly more at 550.

While Cotton On and Glassons weighed in at over 760 grams.

Macpac said they were happy with the results, saying that down jackets provide "excellent warmth to weight ratio, while synthetic fill performs better when wet".

It said lightweight jackets were easier to pack, and provided plenty of warmth without feeling "weighed down".

Kathmandu also said that while warmth was a priority, a good down jacket also offers "generally, a much wider a comfort range than a synthetic fill jacket".

"Some of the warmest jackets that Kathmandu has ever made have also been among the lightest."

Down jacket maker Blair Jacobs - from Wear on Earth - added that jackets should also be ‘down proof’ – that is, made with quality materials that will stop feathers from escaping the fabric.

Glassons was pleased to offer an affordable alternative.

"We are really happy to be able to deliver a lower environmental impact, quality product. We feel recycled polyester provides a more ethical and lower impact to down or virgin polyester."

Cotton On chose not to respond to the results.