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Darn Tough ThermoLite OTC Review

Our favorite midweight synthetic ski and snowboard sock
Darn Tough ThermoLite OTC
Photo: Backcountry
Top Pick Award
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Price:  $24 List | Check Price at Amazon
Pros:  Warm, comfortable, thoughtful ventilation, synthetic construction, durable
Cons:  Underfoot padding holds moisture, specific fit in toe box
Manufacturer:   Darn Tough
By Amber King ⋅ Senior Review Editor  ⋅  Dec 19, 2019
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  • Comfort & Construction - 25% 9
  • Warmth - 25% 7
  • Breathability - 25% 6
  • Fit - 15% 7
  • Durability - 10% 10

Our Verdict

If you prefer polyester to merino wool, the Darn Tough Thermolite Ski Sock is our favorite go-to. This sock offers impeccable durability on the ski hill. It'll keep your foot warm on the coldest days of winter, lasting for many seasons. The polyester fibers offer power wicking power with a thicker construction for more insulation. It has thoughtfully placed ventilation, promoting the removable of moisture. Unfortunately, because the cushioning is concentrated in the bottom of the foot, it can hold moisture, especially if your boots don't breathe. As a midweight sock, it's not meant for those who want thin performance. It's best for skiers who prefer a little more insulation in a sock or snowboarders with appreciate underfoot cushioning. Wear it while slaying the powder on the coldest days of winter.

Our Analysis and Test Results

The Darn Tough Over the Calf is our favorite synthetic sock. If you're allergic to wool or are sensitive to the way even merino wool feels on the skin, this is our best recommendation. It is a top performer built to take on steep slopes littered with groomers, moguls, and more. The cushioned construction offers much in the way of warmth but isn't as breathable as lightweight contenders. The lifetime guarantees it comes with makes is worth the initial investment, allowing you to switch it in if performance deteriorates through its lifetime.

Performance Comparison

This is our favorite synthetic sock for its durable construction...
This is our favorite synthetic sock for its durable construction that provides a great alternative to merino wool. It's comfortable with great overall performance.
Photo: Amber King

Comfort & Construction

This comfortable sock offers lots of cushioning throughout the sole of the sock and on the front of the shin. As a midweight sock, it feels cozy to wear from the hill to the chalet. If you're not a fan of merino wool or are sensitive to its fabrics against your skin, this synthetic sock is our favorite alternative.

Built with 57% polyester with integrated stretch materials (5% lycra spandex), it offers a thoughtful construction that we appreciate for long days on the slopes. If you're a skier or snowboarder that prefers a medium weight sock with boots that aren't uber tight, it'll work well for you.

We enjoy this sock even after doing numerous laps on one of our...
We enjoy this sock even after doing numerous laps on one of our favorite backcountry runs. The synthetic insulation offers great all-day warmth, even when stopping and going.
Photo: Amber King

The sole is completely padded with additional cushioning through the heel, wrapping itself up into the Achilles heel. There is padding that wraps around the bottom and tops of the toes as well, with breathable compartments throughout. The shin also features a very large amount of cushioning that protects well from high impacts to the shins, when flying through the air and landing.

The thicker insulation offers good warmth throughout this sock. Here...
The thicker insulation offers good warmth throughout this sock. Here we see insulation stacked under the foot, which some love. It offers great coziness when lounging around the house and while moving about in the snow.
Photo: Amber King

We also appreciate the compression paneling throughout the arch and at the top of the sock that prevents it from falling down. We skied, snowboarded, and even hiked in this sock, and found it to be quite comfortable for all-day wear.

Here we see the padding along the shin (right) that offers great...
Here we see the padding along the shin (right) that offers great protection from shin bang.
Photo: Amber King


This sock is quite warm, offering cushioning and additional insulation throughout the sock. For its polyester construction, it offers quite a bit more warmth than other polyester socks tested. When wet, the fabric still insulates well and better than the other polyester options in this review. If you prefer a little more insulation in your sock, and use it to offer more warmth on a cold day, this sock delivers.

Since it is constructed out of a synthetic polymer, the fibers are more rigid and cool down faster than Merino wool, so it's not as warm as other midweight merino wool socks. That said, even on days that reached into the double negatives, our feet felt just fine on the chair lifts, especially when ski days were a little more relaxed.

Here we get ready to descent on a colder days in the mountains. This...
Here we get ready to descent on a colder days in the mountains. This sock offers good warmth for all-day warmth.
Photo: Amber King

Given that there is more padding in the sock, this moisture can get trapped. Since polyester isn't as absorbent as merino wool, this sock doesn't do a really good job at wicking it away from the foot. If the moisture can't vent out properly, we did find our feet getting a little chilled on the chair lift. If you sweat a lot in your feet, a thicker sock like this may not be the best option, but if you run cold and need a little more insulation, this is a good choice.


These socks offer great breathability through their fabric. The synthetic fibers are rigid and do an amazing job of wicking moisture from the skin. It also dries out very fast. It has thoughtful ventilation throughout. Even on sweaty uphill adventures, it offers good breathability. However, it doesn't have the same wicking power as a thinner sock option, simply because the moisture can get caught in the thicker underfoot cushioning. If there weren't cushioning under the arch, this sock would be a bit more breathable than other contenders.

This sock offers decent breathability for skiing and touring, but...
This sock offers decent breathability for skiing and touring, but the underside of the foot is a point where sweat like to build up.
Photo: Amber King

Ventilation comes in the form of thinner areas throughout the sock. These are located on the top of the sock and throughout the length of the calf. Given that a high sweat zone sits around the arch, we found moisture to pool and collect in these areas, holding a little more moisture than thinner competitors. Overall, this sock offers the breathability you'd expect out of a high-quality ski sock, but its thicker construction gives it less drying power when stuck inside a boot that isn't well ventilated.

Here we can see that throughout the sock there are many breathable...
Here we can see that throughout the sock there are many breathable points that offer good ventilation.
Photo: Amber King


This sock offers plenty of length throughout the lower calf for leg lengths of all sizes. The amount of cushioning it cozy and comfortable, while the stretch in the fabric is sufficient to keep the sock from sliding down while moving about. Our only caveat with this sock lives in the toe box, which affects the relative fit with a pair of ski boots.

The toe box is quite large with a specific fit that fit only those...
The toe box is quite large with a specific fit that fit only those with really wide feet. The socks are also not specific to the left or right foot.
Photo: Amber King

The toe box has a seam across the toe that we found to bunch and get in the way, especially when wearing it with tight boots. Unlike other Darn Tough socks in this review, this seam seemed to get in the way quite a bit and offered some discomfort. Given that this sock offers more cushioning than most, it works well with a pair of snowboarding boots or a ski boot that isn't the tightest of the tight. However, if your boots are super fitted you might find this toe box seam and additional cushioning a bit of a pain. A thinner sock is a better choice in this case.

The height from the side.
The height from the side.
Photo: Amber King
A look at the relative height from the front.
A look at the relative height from the front.
Photo: Amber King


Bomber! After skiing, snowboarding, hiking, and wearing these socks for over 60 hours, we see no sign of fabric compaction or even fiber disturbance! This is after wearing them when both wet and dry, walking and moving for hours at a time. This is due to its synthetic construction, which is more durable than Merino wool. The polyester fiber is far more durable and bounces back after compaction. It resists breakage, meaning these socks will last even longer than merino sock options. It also integrates nylon, which doesn't only increase its wicking power, but it's tenacity to resist breakdown.

All darn socks that we've tested at OutdoorGearLab, from running to hiking to skiing, seem to last us the longest! Synthetic ones are the biggest workhorses offering impeccable performance. This ski sock will last you for several years. If you happen to blow a hole in it, it's backed by its lifetime guarantee. Even if you own a sock for five years, you can send them back for a new pair. This, in itself, is worth the purchase. We stand behind this sock as durable and well constructed.

Even after 60 hours of use, this high abrasion zone still looks...
Even after 60 hours of use, this high abrasion zone still looks good! This sock is the most durable option tested and a huge favorite.
Photo: Amber King


Given that it comes with a lifetime guarantee and amazingly durable construction, this is one with a high value. While the initial investment might seem high, it pays out in the long run. If you prefer polyester to merino wool, this is our top recommendation. It is warm, durable, and ready to last you for many seasons to come. Just be sure that your ski boot doesn't fit too tightly as the underfoot cushioning is quite ample.

Enjoy this sock for all kinds of adventures. While you're...
Enjoy this sock for all kinds of adventures. While you're adventuring into the mountains via snowmobile or hitting the resort. It's a wonderful option for those seeking a super durable ski sock with synthetic construction.
Photo: Amber King


Choose the Darn Tough ThermoLite Over-the-Calf ski sock if you prefer a synthetic sock to merino wool. It overs a medium amount of cushioning that extends throughout the foot with a padded shin, for all-day comfort. It is best for those with ski boots that aren't too tight or who might need a little more insulation from their sock than a lightweight option.

Amber King

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