The risk of developing a blood clot, specifically Deep Vein Thrombosis (DVT), during air travel is relatively low for the general population but increases with the duration of the flight. Research generally indicates that the risk of DVT is roughly 1 in 4,600 for flights lasting longer than four hours. For flights over eight hours, the risk is slightly higher but still remains below 1% for healthy individuals. The primary cause is "stasis"—the lack of movement in the legs—which allows blood to pool and potentially clot. In 2026, medical experts emphasize that while the "absolute risk" is low, certain "risk factors" significantly amplify the danger. These include a history of clots, recent surgery, pregnancy, smoking, or the use of oral contraceptives. Most traveler-associated clots are asymptomatic and dissolve on their own, but the danger lies in a clot breaking loose and traveling to the lungs, causing a pulmonary embolism. To mitigate this, airlines and doctors recommend performing calf exercises in your seat, staying hydrated, and walking the aisle at least once every hour.