Smartwool PhD Graduated Compression Ultra Light Socks

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Manufacturer Description

We’ve made the most technical wool socks yet with graduated compression. You get improved blood flow, better support a shorter recovery time. This ultra light non-cushioned sock offers a skin-tight fit.


  • Knit in USA of 52% Merino Wool, 42% Nylon, 6% Elastane
  • Graduated compression helps speed recovery
  • WOW Technology in High Density Impact Zones to reduce shock & abrasion
  • Smartwool inside for moisture, temperature, and odor control
  • 20-30 mmHg graduated compression rating
  • Strategic mesh zone for maximum ventilation.
  • Also comes in Light version with more cushioning
  • Measured size medium
    • Length – 47 cm (18.5 in)
    • Weight – 34 g (1.2 oz) per sock
  • Retail – $38

YMMV Review

The Smartwool PhD Graduated Compression Ultra Light Socks are the second pair of compression socks I have been able to review.  The first pair being CEP Compression Running Socks.  The Smartwool socks come in at quite a bit less money, and they stacked up well but there are some variables that have to be thought about. If you would like to know more about wool, check out the article linked below.

Design ★★★½☆

Being that these are Smartwool socks, you know that they are going to be knit partially of wool.  In fact they are 52% wool, 42% nylon, and 6% Elastane.  Each of these fibers has an important role in the socks.  The wool is for moisture, temperature, and odor management.  The nylon helps the sock retain shape and adds durability.  The Elastane is what give the socks their compression and stretch.

The Smartwool PhD Graduated Compression Ultra Light Socks are made with a compression rating of 20 – 30 mmHg (millimeters of Mercury).  This is just below the lower limit of medical grade compression of 30 mmHg.  To do this Smartwool used stronger elastics knit into the socks from the ankle to four inches above the ankle.  This applies pressure from the ankle to the knee, which stimulates circulation and increases blood flow back to the heart.  One of the key things that these socks have is graduated compression.  Some compression socks on the market have more compression in the calf and less in the ankle, this actually produces the opposite effect from what is desired.  The Smartwool PhD Compression Socks have graduated compression with more compression in the ankle and less in the calves to help drive blood flow back to the heart.

Side View

Other features present on these socks it a mesh zone over the toes for strategic ventilation.  They also use their WOW (Wool on Wool) technology in high density impact zones to reduce shock and abrasion.  This is more present in the Light version of the socks.  The whole purpose of compression socks is that you’ll be able to go longer, farther, and harder with less fatigue and better recovery.

Fit ★★★★☆

The fit of the Smartwool PhD Graduated Compression Ultra Light Socks has been good for me but this is where I think these socks can run into a little bit of trouble with some.  I am a men’s size 9 and have always had better luck with a medium sock from Smartwool.  The large always seems just a little too big even though I fit on the bottom side of the large on their sizing charts.  With these socks the medium felt about right on me as well.  They come up to just below my knee and hit me in all the right places on the way up.  As I mentioned in my other Smartwool socks review, I am surprised these are not made left and right foot specific.  This is not the issue with the sizing I am referring to though.

Since Smartwool sizes their socks by your foot size, they are not taking into account your calf or leg size.  This is not that important on regular socks but this is tremendously important on compression socks because this is where the fit needs to be appropriate to produce the correct results.  I am fairly proportionate so it was not really and issue for me but what if you are not proportionate.  By this I mean large or smaller calves than typically seen with your foot size.  This could potentially change the actual amount of compression you receive and therefore your results.  Other compression lines I have seen base their sizing on your calf size to make sure the compression is at the correct levels.  I think that Smartwool should probably look at this or just include it on their sizing charts going forward.  For the record my calves are 38 cm (15 in) in circumference at the widest point.

Performance ★★★½☆

The Smartwool PhD Graduated Compression Socks seem to work.  I say seem because it is really hard to quantify how much it helps.  I like to wear these after my tough workouts and feel like my recovery is faster. The socks are engineering to improve blood flow, flush out lactic acid, and reduce swelling.  I have not had any swelling so I cannot comment on that but the socks definitely help me feel better afterward.  I ran in these a couple times and it is something I am still getting used to.  I think they help a little during the run but I prefer them afterward as a recovery sock.  I am a big fan of wool socks and these are no different.  They are comfortable next to the skin and the best part is they have natural odor control.  The mesh over the toes is a nice feature as well, it actually works.

View of Toe Vent

Overall ★★★½☆

I have been pleasantly surprised by these socks.  I was afraid that the performance would not be there with these but they have performed well.  They are a combination of wool which I really like and synthetic fabrics to create the best sock they could.  The sizing is the only issue I see is that can be an issue for some.  If you are proportionate then these are a good sock at a good price.  Just like other Smartwool socks, these are well made and should last a while.  As always, Your Mileage May Vary.


  • Made with wool
  • Graduated compression
  • Mesh vent over the toes
  • Available with more or less cushioning


  • Size based on foot rather than calf

About the Author

I am an avid runner, cyclist, swimmer, hiker, climber, skier and many other activities that would make this list too long. I started Your Mileage May Vary Reviews in Early 2011 to combine two of my passions: sports and gear.

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