Run light—run right.

The Smartwool PhD Run Ultra Light Micro Sock is a super-lightweight, micro sock that features a blend of moisture-wicking nylon, non-itchy merino wool for comfort and odor prevention, and elastane for just enough stretch to keep your feet moving free on the road or trail.

  • Merino wool/nylon/elastane blend
  • Ultralight
  • Reviews
  • Q & A

Too thin for my taste

  • Familiarity: I've used it several times

Socks were very tight fitting and too thin for my taste. If you want a true minimalist sock this is probably great for you, but if you're looking for any kind of padding, go with something else.

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.

    Look No Further

    • Familiarity: I gave it as a gift but have feedback to share

    If you are in the market for a good pair of low-cut socks, look no further- these are perfect. They're very comfortable, not itchy at all. They do wick moisture as well, so great for working out or just casual wear. My husband has been using them for about two months now and they're still holding up great, but I don't expect them to last forever with how lightweight they are. So it goes with socks! Definitely would recommend these bad boys though.

    Comfy, thin socks

    • Familiarity: I've used it several times

    These socks are super comfy, and very thin. While i like the thin profile, this also means they don't last forever.

    Love them!

      Socks are super comfortable and always keep my feet dry when working out.

      Great Quality

        Nice snug fit that doesn't slip and offers some support. Keeps my feet comfortable and pretty dry. Doesn't stink. Fabric rebounds and can be worn several days in a row with pretty much the same fit. Great socks, worth every penny.

        Gets the job done

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

        Took these out for several miles on the trail, and this has now turned into my favorite running sock. Super soft fabric, and great comfort while running. Pretty impressed with the odor prevention as well. Great light sock for running.

        Over smart wool running socks

        • Familiarity: I've put it through the wringer

        Because they are so comfortable and breathable I have given these socks a pass for too long. Six pairs in the last year is way too many to go through, seems to be be exact same spot that blows out too (right along the toe line). They have a shelf life of maybe 100 miles per pair, which for someone who runs 50 plus miles a week is really just not long enough. I really did love these socks, but have seen the light and found something that don’t fail on me halfway through a run.

        I was Runnin'

        • Familiarity: I've used it several times

        I run fast and my feet don't sweat excessively in these socks. The merino helps to fight those funky odors which is always a plus!

        Love this socks

        • Familiarity: I've used it several times

        I want to buy more, best socks I have ever bought.

        Learn More: Smartwool PhD Socks

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

        Good for short runs

          A thin, comfortable sock. I was hoping for a bit more comfort, which the darn tough vertex gives me, but overall a great sock for running and every day use.

          Love these

          • Familiarity: I've used it several times

          Great socks. Fabric is really comfy and these are perfect for warm days.

          Thumbs Up

            I really like these socks. Comfortable enough to want to lounge around it, but they also hold up during workouts. Great sock for just about everything.

            My New Favorite Socks

            • Familiarity: I've put it through the wringer

            Initially, I was a bit hesitant to splurge on Smartwool socks, but I now regret not making the purchase sooner! These socks are my favorite sock for any type of activity. They're lightweight, breathable, and don't smell horrible after a good sweat session. Durability has been great so far, and they show no signs of wearing out any time soon. Get yourself a pair (or five)!

            Go wool or go home

            • Familiarity: I've put it through the wringer

            Once you've experienced the longevity of a good pair of wool socks (both lifetime and multi-day use) you'll be hard pressed to go back. I generally pack one pair of wool socks per 4-6 days of travel.

            Good versatile socks

            • Familiarity: I've put it through the wringer

            I've used these doing everything from hiking to playing full court basketball and they've performed well. Good moisture wicking, very breathable and extremely light. These socks have done a great job of keeping my feet cool and dry. Another winner from Smartwool.

            Comfortable sock...but thin.

            • Familiarity: I've used it several times

            Huge fan of SmartWools socks, so decided to check out the Ultra Lights. Like all SmartWool socks, this sock is extremely comfortable and super soft. The material is light, so your feet stay cool even through several hours of activity. Compared to the Run Light Elite, the Ultra Lights are noticeable thinner, so I do worry about the durability of the sock in the long haul. This might be my go to 'casual sock' as opposed to 'active sock'. Overall, solid sock, but I might suggest the Light if you plan on using the sock while being active.

            Love These

            • Familiarity: I've put it through the wringer

            I love these socks so much I bought them for a friend for her birthday and she loves them as well.

            SmartWool PhD Run Ultra Light Micro Sock

              Soft and durable....