KEEN.WARM: Insulation for the Thick of Winter
In Portland, we’re scraping windshields and clearing leaves from neighborhood storm drains. Across the globe, though, winter means everything from balmy 50-degree temps to waist-high snow drifts. That’s why we offer a variety of insulation levels—so you can pick the right weight without adding unneeded bulk.
Read on to learn which levels are right for your winter adventure.
KEEN.WARM insulation ratings
Our signature lightweight insulation is called KEEN.WARM. It’s extremely compressible and light for the warmth it provides, plus retains its insulating ability, even when damp. (You can easily find insulated boots when shopping on our site; simply check off “insulated” under the Features section.)
Obviously, you’re going to want more winter protection if you’re snowshoeing than if you’re, say trekking from the parking garage to the office, which is why our boots come in a range of weights, from 100-600 grams.
KEEN.WARM insulation
100g insulation, rated to -4°F/-20°C: Most of our “around town” winter boots feature this weight, which is ideal for mild winter conditions. Think about this as the type of boot you’d wear when you won’t be outside for long periods, like going from the car to the ski lodge.
200g insulation, rated to -25°F/-32°C: The majority of our winter hiking boots and work shoes and boots offer 200g of insulation. This amount provides a barrier between you and the chill without adding too much bulk. It’s ideal for a higher level of activity, like hiking. If you’re going to be doing more standing than moving, you might consider one step warmer.
400g insulation, rated to -40°F/-40°C: This range captures our more extreme winter boots. You can find this heavier insulation in the Men's Summit County boot and kids' Lumi boot, as well as our winter work boot, the Men’s Davenport 6" boot.
600g insulation, rated to -55°F/-48°C: At the time of this writing, we have two severe winter weather work boots. If you’re spending your entire day out in the elements—and those elements are extra cold—600g might be the perfect weight.
Something interesting to note: Due to the colder temps up north, our Canadian work shoes and boots offer heavier insulation than our U.S. versions.
Common questions
What about those temperatures? When it comes to choosing an insulated boot, it’s important to focus on both the insulation weight and the temperature rating. That’s because the warmth of a boot depends on a lot of variables—your circulation, metabolism, how much you sweat, the construction of the shoe, how snugly/loosely the boot fits, and what type of socks are worn.
How is it tested? In order to test styles with KEEN.WARM, we plug the shoe from the top and place it in an insulated cold box. We then leave the shoe in the insulated cold box for 30 minutes. Afterwards, we measure to see how much the temperature dropped inside the shoe.
What happens if it gets wet? KEEN.WARM absorbs less than 1% of its weight in water, which means that it retains heat, even under soggy conditions.
How about sizing? We got a tip from our friends in the KEEN Garage: When choosing a 400g insulated boot, like the Summit County boot, go up half a size. That extra insulation makes for a snug fit and you want to make sure there is room for your toes to wiggle, especially when walking downhill or snowshoeing.
You might also consider how much extra bulk your favorite winter socks will add. If you’re buying shoes in person, bring those socks along trying them on to ensure the best fit.
If you’re going to be tackling snowdrifts, consider an 8" boot. That extra two inches provides extra warmth and a taller snow barrier.
Feet-warming components
KEEN.WARM doesn’t work on its own. There are quite a few elements that work together to ensure toasty toes.
KEEN.DRY: Insulation works in tandem with waterproofing—it’s hard to have warm feet if they’re soaked from slush (or sweat). KEEN.DRY is our proprietary waterproof, breathable membrane that lets vapor out without letting water in.
Thermal Heat Shield Barrier Footbed: This thermal foil barrier inside the footbed keeps the cold out and the heat in by harnessing radiant heat—plus, it has a nice, wooly softness on the outside for added insulation.
Heat Trapolator: A handful of our boots, like the Men's and Women's Revel III boot, offer three layers of innovative heat-trapping materials that are sandwiched underfoot to hold warm air in. This works a lot like the insulation in your house.
Boot height: Another tip from the KEEN Garage: If you’re going to be tackling snowdrifts, consider an 8" boot (most of our hikers are 6"). That extra two inches provides extra warmth and a taller snow barrier.
Socks: It’s nice to have socks of varying weights and thicknesses to complement fluctuating temperatures. This also extends the temperature range of your boots. Look for medium weight crew or over-the-calf socks in merino wool to keep feet warm and dry.
Gaiters: Okay, so we don’t sell gaiters, but if you’re hiking in snow, they’re key to warmer feet.
Want more specific winter boot recommendations? Get tips for choosing the perfect winter boot—or discover how to pick winter boots for kids.
Our warmest winter boots — 200g of insulation or more