Flight Time Estimator
Estimate the flight time between two airports from great-circle distance, aircraft cruise speed and wind, with the local arrival time.
- Flight time
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- Distance
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- Air distance (+6%)
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- Ground speed
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- Time zone difference
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- Arrival (local)
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How it works
The estimator first measures the shortest path over the globe between the two airports with the
haversine formula, using a mean Earth radius of R = 6371 km. That
great-circle distance is the number airlines quote (New York JFK to London Heathrow works out at
5,540 km / 2,991 nautical miles). Aircraft do not fly a perfectly straight line, so the estimate
multiplies it by a routing factor of 1.06 to approximate the real track flown
along airways and around restricted airspace.
Flight time is then block time: 30 min + air distance ÷ ground speed. The fixed
half hour covers taxi-out, the slow climb, descent, approach and taxi-in. Ground speed is the
selected aircraft's typical cruise speed plus the wind you set on the slider — a tailwind is
positive, a headwind negative. Eastbound North Atlantic and transpacific flights usually ride a
50–150 km/h jet-stream tailwind, which is why the return leg is often an hour longer.
If you fill in a departure date and time, the arrival is converted into the destination's local clock using the browser's own IANA time zone database, so summer time on either end is handled for you. The airport list is a curated set of about 120 major international hubs rather than every airfield in the world. Everything runs in your browser with plain JavaScript — no lookups, no sign-up, no ads.
This is a planning estimate, not a timetable. Real schedules depend on the exact routing, air traffic control, runway configuration, weight and the airline's own padding. Always check the airline for the published block time.
Frequently asked questions
How is the flight time calculated?
The tool measures the great-circle distance between the two airports with the haversine formula using an Earth radius of 6,371 km, multiplies it by a routing factor of 1.06 because aircraft follow airways rather than a perfectly straight line, then divides by the ground speed (the aircraft's typical cruise speed plus or minus the wind you set) and adds a fixed 30 minutes for taxi-out, climb, descent, approach and taxi-in.
How accurate is the estimate?
For most city pairs it lands within about 15–20 minutes of the airline's published block time. It cannot know the exact routing, air traffic control delays, runway configuration, aircraft weight or the schedule padding an airline adds, so treat it as a planning figure and check the airline for the real timetable.
Why is the return flight often longer than the outbound?
The jet stream blows west to east across the North Atlantic and North Pacific, so eastbound flights ride a tailwind of roughly 50–150 km/h while westbound flights fight the same air as a headwind. Set the wind slider positive for a tailwind or negative for a headwind to see the difference — on a transatlantic route it is easily an hour.