Kadena Air Base to Halifax / Stanfield International Airport
Approx. 12012 km - about 14h 39m in the air and 16h 03m 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.