I used to land from long flights with ankles that looked borrowed from someone else. After a ten hour flight, my shoes would be tight, my calves would ache, and walking through the airport felt like wading. I assumed swollen legs were just the price of flying. Then a friend who travels constantly handed me a pair of compression socks and told me to try them on the next trip.

That next trip was a nine hour overnight flight, and it changed how I fly forever.

What compression socks actually do

Sitting still for hours lets blood pool in your lower legs. The veins work against gravity, and without movement, fluid settles into your ankles and calves. Compression socks squeeze from the ankle up, with the firmest pressure at the foot and less toward the knee. That graduated squeeze pushes blood back up toward your heart and keeps fluid from pooling.

They are not just for older travelers or people with circulation problems. Anyone on a flight longer than three hours can feel the difference, and they are a standard recommendation for long haul flying.

What I noticed

I wore them for the flight, kept them on through the airport, and took them off at the hotel. My ankles looked normal. My calves did not ache. I walked off that plane feeling like I had taken a short nap instead of a nine hour flight.

The socks I use are a knee high style with 15 to 20 mmHg compression, which is the mild to moderate range that works for travel. That pressure level is strong enough to help but not so strong that they are uncomfortable to wear for a full day.

Tips from my first few flights

• Put them on before you board, not after takeoff. They work best when fluid has not started pooling yet.
• Get the right size. Measure your calf at the widest point and follow the size chart. Too tight cuts off circulation, too loose does nothing.
• Bring a second pair for the return flight, or wash the first pair at the hotel.
• Still get up and walk the aisle every couple of hours. Socks help, but movement is still important.

A good pair costs around fifteen to twenty five dollars. Compared to the misery of a swollen landing, that is the cheapest travel upgrade I own. I do not fly long haul without them anymore.