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.
| Men's | Women's | Insulation | Height |
|---|---|---|---|
| Columba Bugaboot Plus IV | Columba Bugaboot Plus IV | 200g | Over the Ankle |
| Columbia Bugaboot III | Columbia Bugaboot III | 200g | Mid-Calf |
| KEEN Revel IV Polar | KEEN Revel IV Polar | 200g | Over the Ankle |
| Merrell Thermo Chill Mid | Merrell Thermo Chill Mid | 200g | Over the Ankle |
| Oboz 8" Bridger Insulated | Oboz 7" Bridger Insulated | 200g | Over the Ankle |
| Salomon X Ultra Mid | Salomon X Ultra Mid | 200g | Over the Ankle |
| Vasque WT GTX | Vasque WT GTX | 200g | Over the Ankle |
| Vasque Coldspark UltraDry | Vasque Coldspark UltraDry | 200g | Over the Ankle |
| Vasque Snowblime | Vasque Snowblime | 200g | Over the Ankle |
| KEEN Revel IV High Polar | KEEN Revel IV High Polar | 400g | Mid-Calf |
| Oboz 10" Bridger | Oboz 9" Bridger | 400g | Mid-Calf |
| Salomon Toundra Pro | Salomon Toundra Pro | 400g | Mid-Calf |
| The North Face Chillkat 400 | The North Face Chillkat 400 | 400g | Mid-Calf |
| Vasque Snowburban II | Not Available | 400g | Mid-Calf |
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
- Winter Hiking Boots FAQ
- Winter Traction and When to Wear It
- Hiking Gaiters 101
- Hillsounds or Microspikes: How to Choose
- MSR Snowshoe Guide: How to Choose
Thickness is the effective difference.
https://multimedia.3m.com/mws/media/745361O/3m-thinsulate-insulation-type-b-technical-data-sheet-pdf.pdf
Any recommendations on the winter boot with maximum width?
I think Columbia and Keens do Wides.
The Merrell Thermo Chill Mid is available in wide on the Merrell website, though most sizes are sold out. For some reason, the REI website doesn’t list the wide sizes on their product page, but I picked up a size 11W pair today at the NYC flagship, and they seemed to have plenty of wide sizes available.
https://www.merrell.com/US/en/thermo-chill-mid-shell-waterproof/35067M.html
I bought a pair of Keen winter boots a year ago and they are definitely wide. I have a wide forefoot and they fit well.
I think you and I are both still using the Baffin Borealis. How would you fit them into this comparison? I don’t recall seeing any insulation weight rating in their specs.
They don’t. They don’t use thinsulate insulation and are way out of the mainstream having a liner which is more akin to an Intuition ski boot liner or one found in plastic mountaineering boots. I don’t use the Borealis boots for day hiking at all (which is when I use 200g or 400g boots) and only on overnights.
NONE OF THE WELL KNOWN BOOTS YOU LIST PROVOIDE ENOUGH WIDTH FOR MANY OF US. THEIR “WIDE” IS A TOE PINCHING 2E. Not good for many of us with 4E and 6E wide feet and since no one told me over the years, like many, I tolerated boots that I could find and developed Morton’s Neuroma, Thank God for companies that provide decent widths. Just search online.
HINT: With ANY of these boots a Vapor Barrier Liner (VBL) is a necessity to keep foot sweat from compromising the insulation.
VBL SOLUTION: US Divers 3 mm neoprene divers’ sock over a thin poly liner sock. I have use this solution for 20 years with great success. (The brand of VBLs is seam sealed and comes in Right & Left shaped socks.
This 3 mm thickness over a light poly liner sock will not require a larger than normal boot size. For more warmth get a 5 mm VBL divers’ sock and one size larger boot.
->When winter camping I take an extra pair of light poly liner socks for Each day. At day’s end put the skanky wet liners in a Zip Loc quart freezer bag and a new pair on under my heavy wool “sleep socks”.
Then I turn the neoprene VBLs inside-out to dry for 15 minutes before putting them in the foot of my sleeping bag for warm VBLs in the firgid morning. SAVES MY TOES from”cold pain” in the early morning.
This system has worked with both my SOREL felt pacs and SCARPA T-3 Tele insulated ski boot. As well it extends the temp range of my Merrill MOAB Mid GTX hiking boots. With this system and GTX knee-high gaiters I can hike in comfort at 10 F.
Don’t they become swimming pools with nowhere for the sweat to go?
Not if you wear your them when it’s cold out. I can take my 200g boots up to 40F without trouble.
Do you know if Seaskinz brand of socks are considered having a Vapor Barrier Liner?
They’re breathable so by definition, no.
Toundra Pros for me. I’ve been enjoying them all season, hiking, and snowshoeing. Not a blister to be found. They’re super light and fully waterproof and warm as can be. Positively toasty, even when resting on snow. Rated to -40°F, but I dont think they’ll see more than -20°F from me.
Temperature ratings are works of fiction. I live in the Chugach Mountains in Alaska, and I’m on the trail every day walking my dog for 1.5 to 2 hours. In the early part of this winter I saw temps ranges between -15 and 5 F for several weeks. Anything beyond -20 and I won’t be out there anyway. My 200 g Primaloft Adidas winter boots were good to about 0 with thick socks and bed liners, and after that I’d use chemical heat packs. I’ve had 400 g Thinsulate boots (Vasque Snowburbans), but I didn’t find them any warmer so I sold them. Thick socks, bed liners, and heat packs over the toes are the trick, not some bs manufacturer’s claim. No 200 g or even 400 g boot is going to keep your feet warm for very long at -20 F (maybe an hour), no matter how active you are. Most people who buy these boots don’t see anything close to those temps anyway.