Flight socks are the one piece of compression most people buy without a prescription — and the one most often bought in the wrong strength.
Sitting still at altitude is an unusual combination of stresses. Cabin pressure sits around the equivalent of 6,000 to 8,000 feet, the air is dry, and your calf muscle pump is doing almost nothing for hours at a time. Blood pools in the lower leg, and the risk of clot formation rises with the length of the flight.
What the compression is doing
A graduated flight sock is firmest at the ankle and eases towards the knee. That gradient gives returning blood a mechanical assist in the right direction. It is the gradient that matters, not the overall tightness — which is why a tight non-graduated sock is worse than useless.
A tight sock squeezes the whole leg. A graduated sock moves blood in one direction. Only one of those is doing anything useful.Pebble UK fitting team
How much compression do you need?
For most healthy travellers, 15–20 mmHg is the right range for flights over four hours. Below that, 8–15 mmHg is fine for shorter journeys or for people whose ankles simply puff up. Above it, 20–30 mmHg is territory for people with a diagnosed clotting risk, and worth a conversation with your GP first.
Practical points
Put them on before you leave for the airport, not at the gate — the leg is narrower then and getting them on is markedly easier. Walk the aisle once an hour where you can, and keep drinking water. The socks help; they are not a substitute for moving.
Not sure which compression level you need?
Our fitting team have been sizing compression hosiery for 25 years. No obligation, no pressure — just an honest answer.
