Compression sock levels, measured in mmHg, range from 8–15 for mild support to 40–50 for medical-grade compression.
Compression socks use millimeters of mercury (mmHg) to indicate how tightly they squeeze your legs — the same unit used for blood pressure. Higher numbers mean tighter compression, and the pressure is always graduated (tightest at the ankle, looser higher up) to support healthy blood flow. Here is exactly what each mmHg level means and which one you likely need.
What Do Compression Sock Levels Mean?
Each mmHg range serves a distinct purpose, from helping tired legs after a long day to managing chronic venous conditions under medical supervision. The table below breaks down the five standard levels.
| Compression Level (mmHg) | Common Name | Primary Use Cases |
|---|---|---|
| 8–15 | Mild | Minor swelling, tired legs, prevention during prolonged sitting or standing, early pregnancy |
| 15–20 | Medium / Mild Support | Most common over-the-counter entry level; achy or heavy legs, travel, pregnancy, daily circulation support |
| 20–30 | Firm / Moderate | Most prescribed level by doctors; moderate varicose veins, swelling, post-surgical recovery, mild edema |
| 30–40 | Extra Firm | Moderate to severe edema, lymphedema, active venous stasis ulcers, post-fracture or orthopedic surgery |
| 40–50 | Rx / Extra-Firm | Severe venous insufficiency, severe varicose veins, chronic venous insufficiency with skin changes or active ulceration |
European standards label these ranges as Compression Classes (CCL 1 covers 18–21 mmHg, CCL 2 is 23–32, CCL 3 is 34–46, and CCL 4 starts above 49). Most US products and doctors use the mmHg numbers directly.
How to Choose the Right Compression Level
Start low and go slow. For first-time users, the 15–20 mmHg range is a safe starting point for travel, pregnancy, or general leg fatigue. It is available over the counter at drugstores and online without a prescription. For long shifts on your feet, the 15–20 mmHg level offers a solid balance of support and comfort — check our roundup of the best compression socks for 12-hour shifts for top picks in this range.
If you have moderate varicose veins, swelling that does not improve with elevation, or are recovering from surgery, ask your doctor about the 20–30 range before buying. Never start at 30–40 or higher without medical supervision — those levels demand proper fitting and monitoring for skin integrity.
How to Measure for Compression Socks
Getting the right fit matters as much as the right mmHg level. Measure your bare legs first thing in the morning, before they swell from upright activity. Use a soft measuring tape with your feet flat on the floor.
- Mark your leg just above the ankle bone (that is your zero point).
- Measure the circumference at 5 cm, 15 cm, 25 cm, and 30 cm up from that mark.
- Measure the length from the ankle mark to just below the knee.
- For the foot, measure around the heel and ankle bend, and around the metatarsal head.
A common mistake is choosing size based on shoe size — that almost guarantees a poor fit. Follow the sizing chart for the brand you buy, because compression socks must fit snugly without pinching or rolling.
FAQs
Can I sleep in compression socks?
No. Compression stockings are designed for daytime wear while you are upright and gravity is working against your circulation. Sleeping in them can restrict blood flow and cause discomfort. Night garments for conditions like lymphedema use different materials and sizing.
Do I need a prescription for 20–30 mmHg socks?
Lower levels (8–20 mmHg) are available over the counter without a prescription.
What does graduated compression mean?
Graduated compression means the sock is tightest at the ankle and gradually loosens as it moves up the leg. That design counteracts the natural pull of gravity on blood and helps your veins pump blood back toward your heart. All medical-grade compression socks use this graduated design.
References & Sources
- Sigvaris. “Compression Levels — Understanding the Basics.” Covers standard mmHg ranges and their clinical applications.
Mo Maruf
I created WellFizz to bridge the gap between vague wellness advice and actionable solutions. My mission is simple: to decode the research and give you practical tools you can actually use.
Beyond the data, I am a passionate traveler. I believe that stepping away from the screen to explore new environments is essential for mental clarity and physical vitality.