The main benefit of fleece is its effectiveness at trapping body heat and sustaining the warmth. The synthetic fabric is generally made out of polyester. Polyester is a man-made material composed of two petroleum products that can be manufactured from recycled plastic.
Polartec Scale: 100 lightweight, 200 mid-weight, 300 heavy-weight.
Patagonia Scale: R1 lightweight, R2 mid-weight, R3 heavy weight, R4 is a hybrid (see below).
Fleece “weight” refers to the loft and thickness of the material used in a jacket’s construction, and two common scales exist for describing fleece weights. Most companies use the Polartec scale of 100, 200, 300—the higher the number, the higher the loft of the fleece, and the warmer (and heavier) the jacket will be. Fleece jackets with 100-weight ratings are lightweight, highly breathable, offer the wearer a wide range of movement, and work great as light layering pieces for aerobic activities or warmer conditions. Jackets with 200-weight ratings represent the middle ground in fleece, and this tends to be the most popular weight due to its versatility and ease of layering under hardshells. A 300-weight fleece is significantly loftier and heavier, more difficult to layer, and generally designed with cold or extreme weather conditions in mind.
Patagonia developed its own scale for describing fleece weights: R1 to R4. R1 to R3 roughly correspond to the 100 to 300 Polartec scale, whereas R4 is a hybrid fleece combining an R2 grid fleece with a Polartec Windbloc polyester.
What about weights in grams per square meter? This is not an exact science, if you need official weights consult with the fabric supplier or clothing manufacturer. Below is a general estimate as a guide.
<100 gsm Ultra-light
100 – 200 gsm Lightweight
200 – 300 gsm Mid-weight
>300 gsm Heavyweight
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