Run smarter not harder.

The Smartwool Women's PhD Run Ultra Light Micro Sock has just enough sock at the ankle to shield you from cuff on ankle rub but is still lightweight enough to keep you light on your feet. In addition to the the natural breathability of merino wool, mesh ventilation zones promote further ventilation, so you never feel the sweats in your feets. 

  • Merino wool, nylon, elastane blend
  • Reliawool technology
  • Mesh ventilation zones
  • Ultralight weight
  • Reviews
  • Q & A

great for running

  • Familiarity: I've put it through the wringer

I got these for my girlfriend after she was complaining about needing new running socks. She’s been very happy with them. They are light weight and breathable. They’re the perfect height and don’t fall down while she’s running. She wants them in every color now.

great socks!

    I've worn these a bunch since i purchased them and they have been great! They are comfortable and i have not had any foot related issues since i bought them.

    Great Running Socks

    • Familiarity: I've put it through the wringer

    Super breathable and lightweight with the quality you expect from Smartwool. Highly recommend.

    Awesome socks!

      These socks are very breathable and super comfortable. They’re perfect for running and everyday use. I would highly recommend.

      I like these socks

      • Familiarity: I've used it several times

      I really like these socks! They are very light and very breathable. Even after a long day of being stuck in my shoes, they didn't feel like most socks do when you've worn them all day. They were still soft and comfortable.

      Good for summer

      • Familiarity: I've used it several times

      I've been using these to run in during hot, humid, summer mornings. They are light and thin and help with moisture management.

      Thin, Comfortable, Non Slip Socks

        I love these socks for hiking and running. I love wearing them on the hot days with my trail runners. My feet never overheat, and if I step in a wet puddle on a cool day, they don't freeze. Also dry super fast. I'm a huge fan of these!

        Love this socks

        • Familiarity: I've used it several times

        They work great we have been using them for half marathon.

        A good sock

        • Familiarity: I've used it once or twice and have initial impressions

        Smartwool makes quality products.

        Favorite Indoor Running Socks

        • Familiarity: I've put it through the wringer

        I love these socks and bought them in three colors. They are perfect for indoor running and weight training. The sock doesn't slide down into your shoe and is super lightweight. I will probably end up buying every color.

        Obsessed with these socks

        • Familiarity: I've put it through the wringer

        Perfect fit so no bunching or wrinkles to give you blisters. I have a really high arch and these socks have great support there. I also really value that these do not slide down in the back like some other athletic socks I have tried, Oh and they dry really fast too!

        Best. Running. Socks. Ever.

        • Familiarity: I've used it several times

        See title.

        Learn More: Smartwool PhD Socks

        Learn more about the comfort, fit, and durability of Smartwool PhD performance socks. #gofarfeelgood

        Favorite Sock!

        • Familiarity: I've put it through the wringer

        I am about to buy more of these socks because I love them so much! These socks don't fall down on my feet when I am walking compared to cheap cotton socks I have. They fit snug on my foot but not to tight, and the sizing is perfect. I love having wool socks so your sweat doesn't stink up your shoes by the end of the day and the socks don't really smell bad by the end of the day either. One day I am going to buy enough of these that they will be my only ankle socks I own.

        Good Sock to Have

        • Familiarity: I've used it once or twice and have initial impressions

        Very nice, cushy and high quality

        Go-to running sock

        • Familiarity: I've put it through the wringer

        Nice and thin but not so thin you feel like you aren't wearing anything. Wife has multiple pairs and keeps coming back and fun colors are always a plus.

        Comfy and Durable

          I got the Smartwool PHD Ultra Light Run Socks for my wife and she LOVES them. They don't slip at all while she runs and they're padded, but not overly thick.

          The wool wicks sweat effectively and keeps feet warm and happy in all weather conditions.

          Overall, we're big fans of Smartwool socks because they are very comfortable, durable, and machine washable. When other socks get holes in the toes, Smartwool are looking as new as ever!

          Great Socks

          • Familiarity: I've put it through the wringer

          I constantly buy these socks because they are so great.

          Best socks

          • Familiarity: I've put it through the wringer

          I love these socks! I stock up on them whenever possible. They are perfect for running. Thin, don't fall down and great sweat wicking.

          This is my 3rd Pair!

          • Familiarity: I've put it through the wringer
          • Fit: True to size

          I love these socks. They are the perfect socks for hiking and running! They are very lightweight, breathable, and moisture-wicking. The toes have worn out a bit on my older pairs, but I would expect it with how much use I get out of them.