Person putting on knee-high compression socks

Compression Socks: What They Do, Who They Help and How to Pick the Right Pressure

Short answer: compression socks apply gentle, graduated pressure to the lower leg, tightest at the ankle and looser toward the knee. That pressure helps the veins push blood back up toward the heart, which reduces swelling, aching and the heavy-leg feeling that comes from long periods of sitting or standing. For everyday use, travel and mild swelling, 15 to 20 mmHg is the usual starting point. Stronger socks of 20 to 30 mmHg and above are typically used for medical conditions and are best chosen with a doctor.

How do compression socks work?

The veins in your legs have to move blood upward against gravity. They rely on one-way valves and on the squeeze of your calf muscles when you walk. When you sit or stand still for hours, or when the valves weaken with age, blood and fluid pool around the ankles. Harvard Health explains that graduated compression narrows the veins slightly and supports the valves, so blood moves faster and less fluid leaks into the surrounding tissue.

Who benefits from compression socks?

  • People on their feet all day, such as nurses, retail staff, teachers and hairdressers.
  • People who sit for long periods, including long flights and car journeys.
  • People with swollen ankles by the end of the day.
  • People with varicose veins or chronic venous insufficiency, to ease aching and swelling.
  • Pregnant women, because leg swelling and varicose veins are common in pregnancy.
  • After surgery or during reduced mobility, when a doctor recommends them to lower the risk of blood clots.
  • Runners and walkers, who often find them comfortable for recovery, although the evidence for performance gains is limited.

What compression level do I need?

  • 8 to 15 mmHg (light): tired legs, minor swelling, first-time wearers.
  • 15 to 20 mmHg (moderate): the everyday choice for travel, standing jobs, pregnancy-related swelling and mild varicose veins. Available without a prescription.
  • 20 to 30 mmHg (firm): more pronounced varicose veins, moderate swelling and after some vein procedures. Ask your doctor first.
  • 30 to 40 mmHg and above: medical-grade, for conditions such as lymphedema, venous ulcers or after a blood clot. Use only when prescribed and ideally professionally fitted.

You can browse the options in our compression socks range and the wider blood circulation collection.

How do I get the right size?

Size by measurement, not shoe size alone. Measure in the morning, before any swelling builds up: the narrowest part of the ankle, the widest part of the calf, and for knee-highs the distance from the floor to the bend of the knee. A sock that is too loose does nothing. One that is too tight, or that rolls down and forms a band, can cut into the leg and restrict flow.

How do I put compression socks on and how long should I wear them?

  • Put them on first thing in the morning, when your legs are least swollen.
  • Turn the sock inside out to the heel, slide your foot in, then unroll it up the leg. Smooth out every wrinkle and never fold the top band over.
  • Wear them through the day and take them off for bed, unless your doctor tells you otherwise.
  • Wash after each wear to restore the elasticity, and replace them every three to six months, as MedlinePlus advises, because the fabric gradually loses its squeeze.

Who should not wear compression socks?

Check with a doctor first if you have peripheral artery disease or poor circulation in the legs, advanced diabetes with reduced sensation in the feet, heart failure, skin infections, open wounds or fragile skin on the legs. In these situations compression can do harm. Stop wearing them and seek advice if you notice numbness, tingling, colour changes in the toes or skin damage.

When is leg swelling an emergency?

Sudden swelling in one leg, especially with pain, warmth or redness in the calf, can be a sign of a deep vein thrombosis. Seek medical care the same day. Call emergency services if leg swelling comes with chest pain or shortness of breath.

Key takeaways

  • Graduated compression helps leg veins return blood to the heart and reduces swelling and aching.
  • 15 to 20 mmHg suits most everyday needs. Choose firmer levels with a doctor.
  • Measure ankle and calf in the morning, and keep the fabric smooth with no folded bands.
  • Put them on in the morning, take them off at night, replace every three to six months.
  • Artery disease, reduced sensation and skin problems are reasons to ask a doctor first.

Sources

This article is general wellness information and is not medical advice. It does not replace an examination by a qualified healthcare professional. If you have a circulation or heart condition, ask your doctor before using compression.

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