Reviews You Can Rely On

Smartwool PhD Outdoor Medium Crew Review

This model is super comfortable and provides great temperature regulation in a plethora of conditions
smartwool phd outdoor medium crew hiking socks review
Credit: Smartwool
Price:  $25 List
Manufacturer:   Smartwool
By Amber King ⋅ Senior Review Editor  ⋅  Dec 13, 2017
  • Comfort - 25% 9.0
  • Warmth - 25% 8.0
  • Wicking and Breathability - 25% 6.0
  • Durability - 15% 6.0
  • Drying Speed - 10% 7.0

Our Verdict

The Smartwool PhD is a high-performance, fitted merino-blend wool sock that earns a notable mention for comfort and versatility. It is best worn alone, a bonus for minimalists, but a fact that might dissuade buyers accustomed to a dual layer sock system. The PhD is ultra-versatile and comfortable in almost any conditions except for the extreme cold, similar to all other socks tested. We brought it everywhere with us during this testing period. It fits both men and women well because of its compressive paneling and a fitted design. There are women-specific options available.
Super fitted
Lightweight design
Not as breathable as other socks
Pills easily

We love it for hiking, trail running, backpacking, biking, bouldering, and more. In all conditions, it performed beautifully. While other socks might claim a specific advantage, this sock is all around versatile. Its most significant competitor was the Darn Tough Hiker Full Cushion, the men's Editors' Choice winner that won for its ability to breathe better. We also appreciate that it is much more durable than the Smartwool PhD and comes with a lifetime guarantee. However, it doesn't compare to the level of comfort that the Smartwool PhD has to offer. This is a fantastic sock, and a notable mention because of its great performance across a wide range of conditions.

Graphics Update

The colors and graphics of this sock have been updated, shown in the image above. However, there appear to be no technical changes to the sock.

June 2019

Our Analysis and Test Results

The Smartwool PhD is comfortable and versatile. Take this merino-wool blend sock with you anywhere you please!

Performance Comparison

smartwool phd outdoor medium crew hiking socks review - midweight socks aren't as light but still provide decent...
Midweight socks aren't as light but still provide decent breathability. The Smartwool PhD is a classic example.
Credit: Amber King


Of all socks tested, this reigned king in the area of comfort! The Merino-wool blend (63% Merino Wool, 35% Nylon, 2% Elastane) construction, coupled with strategically placed areas of compression under the arch and around the ankle, ensures a nice fit similar to the Darn Tough Light Hiker Micro Crew. The fabric itself is plump and plush with lots of cushion in the heel and forefoot; this makes it a great compadre for long days on the trail.

Our testers agree that the Smartwool PhD is more comfortable than our male Editors' Choice winner - the Darn Tough Full Cushion. The materials are softer and offer more cushioning. That said, in comparison to thewomen's Editor's Choice winner - the Smartwool Hike Medium Crew scored about the same providing a similar level of comfort. While the Smartwool Medium Crew doesn't have the tight compression panels, it has a thicker design with a longer length that kept our testers' feet protected while hiking and even cozier while sleeping in a tent at night.

In addition to its excellent materials, our testers appreciate the height of the sock. It is compatible with both hiking boots and shoes and isn't too long. What's more is that it comes with a "no itch guarantee". Like all the models tested hosting merino wool, you won't find any itchiness while hiking or when the sock gets wet! Overall, if you're looking for a contender that just makes your feet feel cush, this is the one to choose. Wear it on the trail - or to bed.

smartwool phd outdoor medium crew hiking socks review - this sock is comfortable for a variety of reasons. first the...
This sock is comfortable for a variety of reasons. First the compression panelling around the arch and ankle provide fantastic support. Second, the breathable panels keep feet relatively dry. Third, the length isn't too long. Fourth, the material just feels good to the touch.
Credit: Amber King


The thick woven fabric with a 63% concentration of merino wool fibers provides fantastical warmth in both wet and dry conditions. When we armored with this crucial piece of gear in a thin pair of down booties in sub 30 temperatures, it kept our feet the warm just a touch shorter than the Darn Tough Full Cushion, our male Editors' Choice winner. The Smartwool Hike Medium Crew for women also kept our feet a little bit warmer than the Smartwool PhD on the coldest days standing around in the snow.

smartwool phd outdoor medium crew hiking socks review - the smartwool sock (right) proved to be much warmer than most socks...
The Smartwool sock (right) proved to be much warmer than most socks we tested in both wet and dry conditions. It was especially warmer than the coldest sock tested, the Injinji toe sock (left). Here we wake up from a sleeping test in sub-zero temperatures on a Glacier in Alaska.
Credit: Amber King

Wicking and Breathability

While this sock it relatively warm, it's not the most breathable but it does wick well. During our testing, we went running in temperatures that ranged from 60-80 degrees, providing great performance throughout. The Merino fibers are fine enough to allow proper wicking action that is superior to the Darn Tough Full Cushion. However, some points were lost for breathability.

smartwool phd outdoor medium crew hiking socks review - pictured here are four vents. even though the sock strives to be...
Pictured here are four vents. Even though the sock strives to be ultra-breathable, it doesn't compare to other lightweight options. Leave it at home for extreme temperatures (hot and cold), but take it with you for everything else.
Credit: Amber King

Even though our feet weren't as clammy during high-intensity exercise, we noticed our feet weren't as cold. In fact, we opted for thinner socks on hotter days. Overall - the Smartwool PhD is quick to wick, but not the most breathable option out there.


This sock is fairly durable, but not as comparatively durable to other contenders. We wore it while running 28 mile days through the Andes and while backpacking on multi-day trips. We also wore them to work and day hiking. Through this testing period, the cushioning packed down quite a bit, and we observed some major pilling on both the inside and outside of the sock. As a result, we're not as impressed with durability at the sole of the sock given the thin materials at the end of our testing period.

smartwool phd outdoor medium crew hiking socks review - here we see areas of serious fabric compaction withthe smartwool...
Here we see areas of serious fabric compaction withthe Smartwool PhD. If you look to the right of the sole, you can compare the area of high use to the area of low use. You can also observe the pilling we see throughout the body of the sock after 60 miles of exploration.
Credit: Amber King

Drying Speed

When it comes to drying speed, this sock sits in the middle of the road. In terms of drying time, it took 110 minutes to get fully dry. This is largely attributed to its tightly packed wool fibers that absorb more water than other contenders. While the Smartwool PhD dries just about as fast as the Darn Tough Light Hiker Micro Crew. The Wigwam Hiker Pro is the fastest to dry in this review, drying out thirty minutes faster.

Best Application

As an awesome all-around contender, this warm and plush option is cozy and versatile! It performs fantastically in all conditions with the exception of hot weather. We love it for backpacking, day hiking, mountaineering, and more!

smartwool phd outdoor medium crew hiking socks review - exploring the high ridges of alaska proved to be a great use for...
Exploring the high ridges of Alaska proved to be a great use for this sock. Take it with you to the tops of tall peaks and through the deep canyons of the world.
Credit: Highline Running Adventures


For a price of $25, this sock sits at the high end of the price spectrum. Unlike the Darn Tough Full Cushion that offers a lifetime warranty for the same price, Smartwool only advertises a two-year warranty and is one of the least durable socks tested. That said, it has a decent value as it performs well in the field, but we think there are better value options.


Enjoy lavish warmth and comfort with this Notable Mention for Comfort and Versatility.

Amber King
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