Baltimore/Washington International Thurgood Marshall Airport to Hong Kong International Airport
Approx. 13090 km - about 15h 57m in the air and 17h 21m total from gate to gate, at an average speed around 820 km/h.
Real-world flights on routes this long almost always include at least one stop. Use this nonstop estimate as a guide, and allow extra time for connections and layovers when planning your trip.