Compression stockings: how to choose the right class and size

2026-10-16

• Medical stockings apply graduated pressure: strongest at the ankle and gradually less further up the leg.
• A doctor chooses the compression class after an examination and ultrasound; compression is unsafe if arterial blood flow is badly reduced.
• Size is based on morning measurements of the ankle, calf and leg length, not on your shoe size.
• Put stockings on in the morning before swelling builds up, and take them off at once if your toes go numb, hurt or turn blue.
• Look after them gently and replace them once they lose their elasticity.

In a pharmacy or orthopaedic shop it is easy to feel lost: knee-highs, stockings and tights in different colours, preventive and medical versions, and figures in millimetres of mercury on the boxes. It seems enough to pick by shoe size and a nice shade, but compression stockings are a little more complicated than that.

A well-fitted pair eases heaviness and swelling, while the wrong one rubs, slides down, squeezes the leg and ends up in a drawer. Let's look at how compression stockings work, who chooses the class and how to get the size right.

How do compression stockings work?

Medical hosiery applies graduated pressure: highest around the ankle and gradually lower up the calf and thigh. This pressure narrows stretched superficial veins, helps the valves close and supports the calf muscle pump. As a result, blood returns to the heart more easily and less fluid collects in the tissues.

International guidelines regard compression as one of the main forms of conservative treatment for chronic venous disease: it reduces heaviness, pain and swelling. At the same time, compression does not remove veins that are already widened; it helps your legs while you are wearing it.

How do medical stockings differ from preventive ones?

• Preventive hosiery applies light pressure. People without vein disease sometimes choose it for long hours standing, sitting or travelling. It is sold freely, but if you already have symptoms, it is better to see a doctor first.
• Medical hosiery is divided into compression classes. The pressure is stated on the packaging and matches the standard the product is certified to. It is chosen on a doctor's recommendation.
• Hospital or anti-embolism stockings are used in hospital, for example after surgery in patients who are lying in bed. They are not designed for everyday wear.

Ordinary shaping tights and socks with tight elastic have no therapeutic effect, and a tight band can actually hinder blood flow.

Compression classes: who chooses and how?

There are usually four classes, from the first, with the gentlest pressure, to the fourth, the strongest. The exact pressure ranges vary slightly between standards and are shown on the packaging.

• Class 1 is often recommended for early signs: heavy, tired legs, spider veins and mild evening swelling.
• Class 2 is prescribed particularly often: for varicose vein disease, marked swelling, and after sclerotherapy or vein surgery.
• Classes 3 and 4 are used for severe venous insufficiency, skin changes and lymphatic swelling, strictly under a doctor's supervision.

These are only rough guides. A phlebologist chooses the class taking into account the stage of disease, ultrasound findings, and the state of your arteries and skin. We explained what the CEAP disease classes mean in our article on the stages of varicose veins. Compression that is too strong, chosen just in case, can do harm, while compression that is too weak may not help.

When should compression not be used?

Compression is not a harmless accessory but a treatment with its own contraindications. That is why you need to see a doctor before buying medical stockings:

• significantly reduced arterial blood flow in the legs (ischaemia) is the main contraindication; the doctor checks the pulses in your feet and, if needed, measures the ankle-brachial index;
• severe heart failure;
• marked nerve damage with loss of feeling, for example from diabetes, because you may not notice that the stocking is injuring your skin;
• weeping skin conditions or skin infections where the stocking would be worn, or allergy to the material.

If your calves hurt when you walk and the pain eases when you stop, or your feet are always cold and pale, be sure to tell your doctor before starting compression.

How do you find the right size?

The size of compression stockings is based not on your shoe or clothing size but on measurements of your leg. Whether the pressure is right depends on how accurate those measurements are.

1. Measurements are taken in the morning, soon after waking, before any swelling. If that isn't possible, take them after resting lying down with your legs raised for 15–20 minutes.
2. The circumference just above the ankle bones and at the widest part of the calf is measured, plus the thigh and leg length for stockings and tights.
3. It is best to have measurements taken by a trained fitter in an orthopaedic shop or pharmacy.
4. The figures are then checked against that particular manufacturer's size chart, as sizing differs between brands.

If you fall between sizes, or one leg is noticeably larger than the other, don't guess: a specialist will suggest a suitable model, and sometimes stockings are made to measure.

How to wear them: knee-highs, stockings or tights?

The length is also chosen by your doctor, depending on where the affected veins are. Knee-highs are suitable if the problem is limited to the lower leg, while varicose veins in the thigh need thigh-length stockings or tights. In the summer heat many people find knee-highs and thin, breathable fabrics more comfortable, so discuss this with your specialist.

• Put your stockings on in the morning, before your legs swell.
• Turn the stocking inside out down to the heel, slip your foot in and gradually ease it up the leg without rolling it into a band. Rubber gloves and special donning aids help.
• Make sure there are no wrinkles and that the top band doesn't fold over or dig into the skin.
• Stockings are usually taken off at night unless your doctor advises otherwise. In the evening, look after your skin with a moisturising cream.
• Wash by hand or on a delicate cycle in warm water with a mild detergent, and dry them flat, away from radiators and direct sun.

Over time stockings lose their elasticity, so they are replaced, usually every few months; the manufacturer gives the exact period. If a pair has become too easy to pull on and slides down, it is probably no longer working. Many doctors also advise compression on long flights; read more in our article on frequent flights. And stockings work best together with movement, as we explained in our article on walking for healthy veins.

The main points

Compression stockings are a reliable ally in vein disease, but only when they are chosen correctly. Your doctor sets the class, accurate morning measurements set the size, and daily wear and gentle care deliver the benefit. Find a specialist you trust, choose a comfortable model, and your stockings will become not a burden but a familiar part of your morning.

Sources: 1. De Maeseneer MG, Kakkos SK, Aherne T, et al. ESVS 2022 Clinical Practice Guidelines on the Management of Chronic Venous Disease of the Lower Limbs. Eur J Vasc Endovasc Surg. 2022;63(2):184–267. 2. Clarke MJ, Broderick C, Hopewell S, et al. Compression stockings for preventing deep vein thrombosis in airline passengers. Cochrane Database Syst Rev. 2021;4:CD004002.

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