Circulation
Compression socks for long flights: how to choose
Most travel compression socks sit at 15–20 mmHg. The strength on the label matters less than getting the size right, and no sock replaces moving, hydration, and a word with your doctor if you have clot risk factors.
7 min read. Last updated 2026-08-20.
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What compression socks do on a plane
Sitting still for hours slows blood flow in the deep veins of your legs, and fluid pools in your ankles. Graduated compression is tightest at the ankle and eases up the calf, which helps push blood back toward the heart. That is why most people notice less swelling rather than more energy.
Choosing a strength
Compression is measured in mmHg. Travel socks are usually 15–20 mmHg. Higher strengths exist but are medical devices and should be chosen with a clinician.
- 8–15 mmHg: very light; mostly comfort
- 15–20 mmHg: the usual long-haul travel range
- 20–30 mmHg and above: medical grade, so get advice before flying in these
- Avoid products that only say 'firm' or 'strong' with no number
Getting the size right
Fit failures cause nearly all complaints. Measure your ankle and the widest part of your calf in the morning, before swelling builds, and buy to the chart rather than to your usual sock size.
- Match both shoe size and calf circumference
- Knee-high is enough; thigh-highs are harder to keep up
- A cuff that digs in or rolls is the wrong size, not something to endure
- Put them on before you leave home, not at the gate
What they do not do
Compression socks are one part of reducing travel clot risk, alongside moving regularly, staying hydrated, and avoiding hours of unbroken stillness. They are not a substitute for medical advice if you have had a clot, recent surgery, active cancer treatment, or are pregnant.
Care and replacement
Compression fabric loses elasticity. Wash in cool water, skip the tumble dryer, and expect to replace regularly used pairs after a few months.
Things worth buying properly
Graduated compression socks (15–20 mmHg)
Budget · $15–$35 per pair
The single most useful thing most long-haul travellers over 50 can pack.
What to look forUnder-seat foot hammock
Budget · $15–$30
Cheap, light, and surprisingly effective for shorter legs.
What to look forElectrolyte drink packets
Budget · $1–$2 per serving
Makes plain water easier to actually drink on a dry flight.
What to look forWe earn a commission on some links, at no extra cost to you. It never changes what we recommend or what we say about the downsides. More in our disclosures.
Common questions
- What strength compression socks should I wear on a long flight?
- 15–20 mmHg graduated compression is the usual range for travel. If you have a history of blood clots, diabetes, peripheral artery disease, or have had recent surgery, ask your doctor which strength is appropriate for you.
- How long should I wear compression socks when flying?
- Most travellers put them on before leaving home and keep them on until arrival, including transit. If your feet go numb, change colour, or hurt, take them off, because that indicates a fit problem.
- Do compression socks prevent blood clots on flights?
- They are one measure among several and do not eliminate risk. Public health guidance also emphasises moving your legs, walking when it is safe to do so, and staying hydrated. Discuss personal risk with your doctor.