Thinsulate is a very thin but warm synthetic insulation, commonly used to insulate winter hiking boots and winter clothing. It’s available in different grades, commonly referred to as 100g, 200g, 300g, …1000g. Winter hiking boots are usually insulated with 200g or 400g Thinsulate insulation, although some boots are available with 600g insulation. These weights refer to the thickness of the insulation used to insulate the boot, not the weight of the insulation in the boot.
For example, a 200g insulated boot doesn’t have 200 grams of insulation (which would make the boots quite heavy) but is insulated with Thinsulate that weighs 200 grams per square meter. A square meter is over 10.7 square feet, which is far larger than the insulation contained in a single boot or a pair of 200g insulated boots. A square meter of 400g or 600g Thinsulate is much thicker and therefore warmer than 200g Thinsulate insulation because it lets less heat escape.
Winter Boot Temperature Ratings
Most winter boot manufacturers claim that a 200g Thinsulate boot will keep you warm down to 20 below zero Fahrenheit, a 400g one will keep you warm down to 40 below zero Fahrenheit, and a 600g boot, down to 60 below zero Fahrenheit. Beware of the fine print, because many of these temperature ratings assume that you’re active and hiking vigorously and not standing around on cold pavement or shivering at a bus stop.
Boot Height: Over-the-Ankle vs Mid-Calf
Another key difference between 200g and 400g winter boots is how high they extend up your leg. Most 200g winter boots are over-the-ankle, so-called”Mid” height, while 400g winter boots extend higher up your leg to mid-calf. This lets them retain more body heat, so your feet stay warmer.
Generally speaking, you can wear a pair of 200g winter boots in 30-40 degree Fahrenheit temperatures quite comfortably without sweating. This makes them an attractive footwear option for hiking in colder autumn temperatures when it freezes at night but is warmer during the daylight hours.
More Winter Footwear FAQs
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