How to Read a Compression Sock Package: Decoding mmHg, Class, and Spec Labels

Last reviewed: August 10, 2026 · Compression Socks Canada Team

Buying compression socks for the first time can feel like reading a different language. Packages list millimetres of mercury, classes, lengths, knit types, fabric blends, toe styles, and donning notes — sometimes in the same paragraph. The labels are not designed to be cryptic; they are designed to convey medical information accurately. Once you know what each element means, the package becomes a simple specification sheet rather than a wall of jargon. This article walks through every major element you might encounter on a compression sock package, what it means, and why it matters when choosing the right product. It is general educational content and not a substitute for medical advice.

The single most important number: mmHg

mmHg stands for millimetres of mercury, the standard medical unit of pressure. It is the same unit used on a blood pressure reading. On a compression sock package, the mmHg figure tells you how much pressure the stocking applies at the ankle. Most graduated compression products list a range — for example, 15-20 mmHg or 20-30 mmHg — because the pressure varies slightly based on leg shape and the way the stocking is worn.

The most common ranges in Canada are:

• 8-15 mmHg: mild compression. Often used for comfort wear, travel, mild swelling, and seniors with fragile skin. Browse 8-15 mmHg compression socks.
• 15-20 mmHg: moderate compression. A very common starting point for many situations including travel, work-day wear, mild varicose veins, and early or preventive use. Browse 15-20 mmHg compression socks.
• 20-30 mmHg: firm compression. Often used for diagnosed venous insufficiency, more pronounced varicose veins, post-sclerotherapy support, and active swelling. Browse 20-30 mmHg compression stockings.
• 30-40 mmHg: extra-firm compression. Typically reserved for more advanced venous disease, post-thrombotic syndrome, severe edema, and venous ulcer management. Browse 30-40 mmHg compression stockings.
• 40-50 mmHg and above: very high compression. Used for specific conditions such as advanced lymphedema, usually in custom flat-knit garments.

The higher the number, the firmer the squeeze at the ankle. Higher is not automatically better. The right class depends on what you are using the stocking for and what your physician or vascular specialist recommends.

The graduated profile

Look for the word graduated on the package. Graduated compression means the pressure is highest at the ankle and decreases as the stocking moves up the leg. That gradient is what supports venous return mechanically. A non-graduated tube of fabric — even if it feels tight — does not produce the same effect.

Most medical-grade products are clearly labelled as graduated. Athletic recovery sleeves and novelty compression products sometimes are not. If the package does not say graduated, assume it is not.

Length: knee-high, thigh-high, pantyhose

The next major spec is length. The package will indicate one of:

• Knee-high (also "calf-high"): covers the foot and calf up to just below the knee. The most common length. Browse knee-high compression socks.
• Thigh-high: covers the foot, calf, and thigh up to the upper leg. Used when symptoms extend above the knee. Browse thigh-high compression stockings.
• Pantyhose: covers both legs and the pelvis as a single garment. Useful for pelvic pressure and full-coverage symptoms. Browse compression pantyhose.
• Maternity: a pantyhose variant with extra room in the abdomen. Browse maternity socks.

Sometimes a package will use a letter code instead of a word — for example, AD (ankle to below knee), AG (ankle to groin), AT (ankle to thigh), AF (full pantyhose). The letter codes appear on European-spec packaging more often than North American.

Toe style: open vs closed

The toe end of the stocking is either open or closed. Each has a specific use case:

• Closed toe: the stocking covers the toes. Browse closed-toe compression.
• Open toe: the toes are exposed. Browse open-toe compression.

Closed toe is the standard choice for everyday wear and cold weather. Open toe is useful when you want to wear sandals, when the toes are arthritic or sensitive, or when the foot size is at the edge of a size range and a closed toe would be too tight. Open toe also makes donning easier when used with a slick toe sleeve.

Material and knit

The package will indicate the fabric blend. Common fibres include:

• Nylon and elastane (spandex). The base of most compression products; provide the stretch and recovery that produce pressure.
• Cotton. Adds softness and breathability. Sea-island cotton blends are common in mid-range stockings.
• Merino wool. Excellent temperature regulation and odour control; popular for athletic and outdoor use.
• Microfibre. Smooth, soft, and unobtrusive under dress trousers.
• Sheer hosiery blends. Resemble regular hosiery while delivering compression.
• Bamboo blends. Soft, breathable, and a sensible choice for sensitive skin.

Beyond the fibre blend, you may see indicators of knit type:

• Round-knit: seamless fabric knitted on a circular machine. Thinner and more cosmetic; suits relatively symmetrical legs.
• Flat-knit: heavier fabric with a seam, used for limbs with irregular shape or for stronger containment in lymphedema and severe edema. Browse the compression garments collection for custom and off-the-shelf flat-knit examples.

Sizing: not just "medium"

Compression stockings are sized based on specific leg measurements, not a generic small / medium / large. Common measurements include:

• Ankle circumference at the narrowest point above the malleolus.
• Calf circumference at the widest point.
• Thigh circumference for thigh-high stockings, measured at the widest point under the gluteal fold.
• Leg length from floor to either the knee crease or the gluteal fold.

The package or the manufacturer's size chart converts these measurements into a size. Two stockings with the same nominal size (such as "medium") from different brands can fit differently. Always check the actual measurements against the chart for the specific product.

Stockings that bunch, roll, or pinch a single section of skin are the wrong size. They are not delivering the intended pressure profile and should be exchanged.

Brand and product family

The package will identify the brand and the specific product family. Major brands carried in Canada include:

• Sigvaris
• JOBST
• Actimove (orthopedic supports and bracing)
• Mobilis by Sigvaris

Each brand publishes its own size charts and product specifications. Sizing within a brand is more consistent than across brands.

Compression class versus mmHg range

Some packages, especially those using European-style classification, list a compression class in addition to or instead of a mmHg range. The mapping varies slightly between European systems and the older Canadian/US convention, but a useful general guide is:

• Class 1: 18-21 mmHg (close to North American 20-30 mmHg).
• Class 2: 23-32 mmHg (overlaps with 20-30 and 30-40 mmHg).
• Class 3: 34-46 mmHg.
• Class 4: above 49 mmHg.

If the package uses class numbers and you are unsure of the conversion, the mmHg range printed alongside is the clearer reference. When in doubt, confirm with the supplier or a fitter.

Other label details worth noticing

• Wash instructions. Most compression products are machine washable on gentle cycles and best air dried.
• Country of manufacture. Often listed; many premium brands are made in Switzerland, Germany, or Italy.
• Date of manufacture. Compression elastane has a shelf life. Older stock may have reduced recovery.
• Skin tone or colour option. Especially for sheer hosiery and dress styles.
• Reinforced zones. Some packages call out reinforced heel and toe for durability.
• Silicone band indicators. Thigh-high stockings list the band style (silicone dots, silicone lace, or no band).
• Donning aid compatibility. Some products are explicitly designed for donning aid use.

Choosing the right class for your situation

For Canadians without a medical reason to require a specific class, sensible starting points are:

• Travel, work-day wear, mild swelling: 15-20 mmHg.
• Diagnosed venous insufficiency, varicose veins, post-procedural support: 20-30 mmHg.
• Severe venous disease, post-thrombotic syndrome, venous ulcer prevention: 30-40 mmHg (with clinical guidance).
• Mild swelling in older adults with fragile skin: 8-15 mmHg.

For any diagnosed medical condition, the class belongs with a physician or vascular specialist. Many of our other guides — such as the chronic venous insufficiency article and the post-thrombotic syndrome article — go into condition-specific recommendations.

Putting it together

A compression sock package contains a precise specification of what you are buying. The mmHg figure tells you the pressure; the word "graduated" confirms the profile; the length and toe-style choices match the symptoms; the size chart matches the body; the fabric blend and knit type match the use case. Once these elements are familiar, comparing products becomes simple. The right stocking is the one whose specifications match your situation — diagnosed condition, lifestyle context, skin and dexterity considerations — and whose fit is confirmed against actual measurements rather than a generic size guess. With the right product correctly fitted, daily compression delivers exactly what it is engineered to do.

Frequently asked questions

Is higher mmHg always better?

No. Higher pressure is harder to don, less comfortable, and is not appropriate for everyone. Higher pressures can also be unsafe in legs with significant arterial disease.

What is graduated compression?

Graduated compression delivers firmer pressure at the ankle that decreases up the leg. This profile is what supports venous return.

What does AD or AG mean on a package?

European length codes. AD is knee-high, AG is thigh-high, AT is a thigh-high variant, AF is pantyhose.

Do sizes match across brands?

Not exactly. Always check the size chart of the specific product.

What is the difference between round-knit and flat-knit?

Round-knit is thinner, seamless, and good for relatively symmetrical legs. Flat-knit is heavier, seamed, and better for irregularly shaped limbs and stronger containment.

How long does a compression stocking last?

For daily wear, typically three to six months before elastic recovery declines.

Related reading

• Different types of compression socks: understanding the grades
• Finding the perfect fit: compression socks sizing guide
• How do compression socks work?

This article is general educational content. For diagnosed medical conditions, confirm product selection with a physician or trained compression fitter.