SmartWool Microweight Thong - Women's

It might look like underwear, but it's so much more.

The SmartWool Women's Microweight Thong does more than just look good. It gives you unparalleled next-to-skin comfort. The natural properties of merino wool help your skin regulate its temperature and stay dry.

  • Super-soft merino wool naturally insulates, wicks moisture, and inhibits the growth of odor-causing bacteria
  • Flatlock seams won't create friction points that can irritate the skin like traditional stitching can
  • UPF 50 blocks the sun's harmful rays before
  • Reviews
  • Q & A

Love that merino!

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: Large

I agree with the other reviews that it may be a good idea to size up. These were just a tiny bit tight on me, but not so tight that I won't wear them. Other then that they are still great material!

Runs slightly small but still comfy

  • Familiarity: I've used it once or twice and have initial impressions
  • Fit: Runs small
  • Size Bought: M

I like the style and large band. Design is great. I also like the feel of these - just like cotton but wool. However, the size S was too small and could have used a M.

runs small

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

Runs small, I usually wear a large and figured that would be just fine but its tight, so definitely size up. A good option for an active girl,but doesn't want seams showing.

Size up!

  • Familiarity: I've used it several times
  • Fit: Runs small

Read reviews but did not size up. Should have gotten the medium! The small fits ok but digs in a bit. I can make due but for future orders will get medium.

Totally fine, just size up.

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: large

I like these, but the larger size is much better than my "normal" size, medium. I ordered both the medium and large, after reading the reviews. The mediums are okay in the length and I still wear them, but the width of the band is really tight and they give me muffin top. I also have these in the bikini cut, and the medium is perfect. The large fits much better and more comfortably, in this thong.

I have done a number of exchanges for customers, on these, and they all size up. So, I really suggest sizing up, even though one reviewer on here said that she wishes she wouldn't have.

More questions? Just call or email me, directly.

I wanted to love it

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: Small

After the first wear there was a hole near the seam, which I repaired. Another hole developed in the middle of the fabric after the second wear. I've been looking for a durable and comfortable merino thong for hiking, so I really wanted to love these but they are not of great quality... They also ride up and are not as soft or comfortable as my other Stoic merino boxers (which I love).

The fabric seems very thin and not durable enough for hiking or sports. The waistband on the other hand is unnaturally thick compared to the overall fabric. Cheaply made and too expensive for the quality, maybe I got a defective pair...?

Hi there! I would like to purchase some of the smart wool thong, but I don't like big waistbands. In the pics it looks like the Silver grey/heather teal has a slim waistband, but the black and bright pink have thick waistbands. How can they be the same item? Can you please let me know so I can purchase the colours that come in the thin waistband only. Many thanks

Hey, this is probably too late, but I have a bunch of the grey heather/teal style in this and this seems to be the old version. I don't have any of the new version, but compared to the my "old" version ones, I am not concerned that this waistband will be too big. It looks like they made these seamless for the updated version... Hope this helps! OH, and size up from her regular size....

Fast Drying

    My go-to for backpacking and bike touring. When traveling light; these do the trick, these line dry in just a few hours.

    Not itchy - really

    • Familiarity: I've used it several times
    • Fit: True to size

    Ok, so you were a bit skeptical? I was, but there's no reason to be. These are soft, and stretchy so no chafing or itching. Seems are all in the right place. Have to cut the tag off, that thing is huge. Oh, and when your out wearing things over and over, a rinse and they are back to new. No smell!

    Best sporty thong ever.

    • Familiarity: I've used it several times
    • Fit: True to size

    I'm not going to share a photo, but I have used Patagonia's discontinued capilene thongs forever. These are a great upgrade. Thanks, SmartWool!

    made the mistake of sizing up

    • Familiarity: I've used it several times
    • Fit: True to size

    After reading reviews that these ran really small, I ordered one size up from my normal size. When I first put them on they fit great, but with any movement they stretch out and begin to lose their shape. There isn't enough material in the crotch area so when the loosen up they start to move into places they should not and it's extremely annoying. These are the only thong wool underwear I've found, so I'll give them another try in my normal size (medium.) As far as the material, it does what it's supposed to and wicks moisture and prevents any odors.

    Comfiest Thong EVER

    • Fit: Runs small

    I bought these after getting some merino briefs for hiking (one from SmartWool and one from Icebreaker). They turned out to be so much drier, softer and more breathable than cotton not just for hiking but for everyday wear. So, needed an awesome merino thong to wear with leggings too. It's like I'm not wearing anything, they're so comfy. Thanks to other reviewers, I ordered a size up from my usual SmartWool size and it fit perfectly. Thanks to backcountry for keeping these in stock, they're hard to find!

    Love these things!

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

    Soft, comfy, dries so quickly, does not retain much odor. The sizing seems accurate to me, although I have a pair from another site that does run 1 size smaller. I hand wash or use a lingere bag in the washing machine, then hang to dry. No showing through, no shifting or bunching. Liners don't adhere well (the lanolin in wool?) I have 3 pairs, one has stitching coming out and the thong part is twisty, but I LOVE the other two, wear them every day if I can.

    Funny Fit

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

    I took these with me on a three month backpacking trip and they drove me crazy. Every five to ten miles I would have to stop and adjust them because they would ride up in the front (they just didn't fit properly). It doesn't sound like a huge deal, but it gets old really quickly. I really wanted to like them, but they just weren't functional compared to other brands of the same style.

    Smartwool Microweight thong

    • Familiarity: I've put it through the wringer
    • Fit: Runs small

    Although this bottom should be the exact counterpart to the women's merino hiphugger by smartwool it's not. The design and look is exactly the same but the sizing is 1 too small. I would highly recommend sizing up.

    Poorly made and way smaller than sized

    • Familiarity: I returned this product before using it
    • Fit: Runs small

    I didn't even get to try this out! I was very excited as I've worn a wool bikini panty before and it was great, but this smartwool thong was just pathetic. I like how the stitching on the thong part is, but the seam at the hip was coming undone out of the package. Also, the sizing is just way off! Per their size chart I should be a Large, but as I've looked at their bikinis in a store and noticed they seemed small, I sized up to an XL. This pair may have fit a medium snugly. Who wants tight and constricting underwear? Come on smartwool! Way overpriced for this product. A good idea, but poor execution.

    How durable are these? Has anyone worn...

    How durable are these? Has anyone worn them on long trips?

    Best Answer

    They don't wash well - I won't buy another pair. After 3 washings, they are falling apart.

    I have about ten pairs of these now that I have been wearing daily for a few years. I wash and dry them in the washer and dryer and they have held up fairly well although the fabric is very light, so you do have to take some care.

    SmartWool Thong a new favorite of mine!

    • Familiarity: I've used it several times

    The SmartWool thong is comfortable, wicks away moisture and allows air-flow where it ought too! I love these for the gym, running, or just hanging out.


      You lay upon my buns so neatly,
      and keep me smelling oh so sweetly,
      with not a line upon my seat,
      for playing outside you can't be beat.


      Great Undies!

        Thongs are great for the 'barely there' feel and leave NO lines under clothing. These are the best! I am replacing all my underwear with Smartwool thongs! LOVE them!!

        Can be sink washed and air dried. Great for travel!