Washington Dulles International Airport to Ninoy Aquino International Airport
Approx. 13769 km - about 15h 23m in the air and 16h 41m total from gate to gate, at an average speed around 895 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.