15–25 mmHg Graduated Compression Socks, Explained
Every compression sock has a number on it — 8–15, 15–20, 20–30 mmHg — and almost nobody explains what it means before you buy. Here's the plain-English version, and why we build our socks at 15–25.
What mmHg actually means
mmHg stands for "millimeters of mercury" — the same unit a blood-pressure cuff uses. On a compression sock it describes how much gentle pressure the knit applies to your leg. A range like 15–25 mmHg means the sock is knit to apply up to 25 mmHg at the ankle, easing down to around 15 as it moves up the calf.
That fade from ankle to knee is the whole trick — it's called graduated compression: firmest where fluid pools most (the ankle), lighter where your leg needs freedom (below the knee). A sock that squeezes the same everywhere isn't graduated — it's just tight.
The compression levels, compared
| Level | How it feels | Typical use |
|---|---|---|
| 8–15 mmHg (light) | Barely-there hug | Everyday "energizing" socks; often too light to notice by evening |
| 15–20 mmHg (mild-moderate) | Noticeable, easy to wear | The most common non-medical level: work, travel, daily wear |
| 15–25 mmHg (moderate — ours) | Firm at the ankle, wearable all day | Long shifts, long flights, long days on your feet |
| 20–30 mmHg (firm) | Strong, deliberate squeeze | Often recommended by clinicians for specific needs — follow your doctor's guidance |
Honest note: brands measure and label ranges slightly differently, so treat the numbers as a guide, not a lab certificate. What matters most is graduated design + the right size.
Why we knit at 15–25 mmHg
We sell one sock, at one level, on purpose. 15–25 sits in the everyday sweet spot: firmer at the ankle than a typical 15–20 sock, without the tourniquet feel of a 20–30 medical grade. It's the range where support is strong enough to feel on hour ten of a shift or hour nine of a flight — and comfortable enough that you'll actually keep the socks on, which is the only way any compression level does its job.
The best compression level is the one you'll wear all day. That's the entire design brief behind 15–25.
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Getting the level right is half the job — size is the other half
A perfectly chosen mmHg range in the wrong size feels wrong in both directions: too small and even 15–20 feels like 30; too big and 15–25 barely registers. Size runs on two numbers — shoe size and calf girth — and the calf wins any disagreement. Our 2-minute size guide covers it, and fuller calves get their own fit on the wide calf page (XXL fits up to 28-inch calves).
15–25 mmHg FAQ
Is 15–25 mmHg too tight for all-day wear?
No — in the right size it reads as a firm, even hug that's strongest at the ankle. You notice it in the morning and mostly forget it by mid-morning. Throbbing or numbness means the size is wrong, not the level.
What's the difference between 15–20 and 20–30 mmHg?
Intensity. 15–20 is the common everyday level; 20–30 is a firm grade that clinicians often recommend for specific situations. 15–25 — our level — sits between them: more ankle support than 15–20, without the effort and intensity of 20–30.
Which mmHg should I choose for flying?
Most travelers pick a moderate graduated level they can wear the whole travel day — check-in to hotel. That's the use case 15–25 was tuned for; our flight socks guide has the full routine.
My doctor prescribed a specific compression class. Should I still buy these?
Follow your doctor. Prescribed compression exists for medical reasons, and their number beats ours. The Well Socks are a comfort and wellness product, not a medical device.
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Keep reading: What graduated compression actually does · How long to wear compression socks · Compression socks for standing all day
The Well Socks compression socks are a comfort and wellness product and are not intended to diagnose, treat, cure, or prevent any disease or condition. If you have serious circulation problems, diabetes-related foot complications, severe swelling, skin wounds or infections, or known vascular disease — or if you are pregnant — consult a qualified healthcare professional before use.