Flight time: how distance and speed set the duration
Booking a flight involves more than comparing prices: the travel time between two cities depends on distance, cruising speed, wind direction, and time zone crossings. A flight duration calculator estimates how long a trip takes between any two airports, helping travelers compare itineraries and plan layovers. The core physics is simple, distance divided by speed, but real flights add takeoff, landing, taxiing, and wind effects.
TL;DR
- The calculator determines the great-circle distance between the two airports, then divides by the typical cruise speed of a commercial jet, around 900 km/h (560 mph) in still air
- Formula: Distance = R × arccos(sin φ1 sin φ2 + cos φ1 cos φ2 cos Δλ) | Air time = Dista
- Example 1: New York to London, about 5,570 km
How it works
The calculator determines the great-circle distance between the two airports, then divides by the typical cruise speed of a commercial jet, around 900 km/h (560 mph) in still air. Headwinds and tailwinds modify the effective ground speed, and taxi, climb, and descent phases add roughly one hour to the airborne time. Still-air estimates understate real long-haul schedules: typical New York, London block times run 7 to 7.5 hours. For clock-time math between start and end hours, including overnight shifts, use the hours calculator as a companion.
The math
Enter the flight distance and the expected ground speed. Dividing the distance by the speed yields the airborne time shown by the calculator; adding taxi, climb, and descent overhead, roughly one hour on long flights, gives the block time between gate and gate. For airport-to-airport trips, the great-circle distance (haversine formula) is the correct distance to use.
The haversine formula accounts for the curvature of the Earth, which is why flight paths on flat maps appear curved.
Examples
Example 1: New York to London, about 5,570 km
- Still-air time: 5,570 ÷ 900 ≈ 6.2 hours
- With the jet stream: eastbound often under 6 hours
- Add taxi, climb, and descent overhead: about 7.2 hours block time
- The return trip westbound takes roughly an hour longer
Example 2: Rome to Berlin, about 1,180 km
- Still-air time: 1,180 ÷ 900 ≈ 1.3 hours
- Taxi, climb, and descent overhead: about 40 minutes
- Typical schedule: about 2 hours
- Scheduled times match this estimate closely
When to use it
✦ Trip Planning and Comparisons
Travelers compare direct and connecting options, choosing between shorter flights and cheaper itineraries with full knowledge of the time cost. For hour differences between two clock times, the hours calculator handles start and end times including overnight spans.
✦ Business Scheduling
Professionals estimate arrival times and meeting feasibility across time zones, accounting for time zone shifts on top of block time.
⚠ Common mistakes
- Ignoring Wind Direction: The same route takes much longer westbound against the jet stream than eastbound with it.
- Confusing Air Time and Block Time: Scheduled durations include taxiing and climb; the pure airborne distance calculation is always shorter.
- Forgetting Time Zones: A 7-hour flight from New York to Rome lands 13 hours later in local time, because Rome is 6 hours ahead of New York.
FAQs (5)
Why is the return flight longer?
At mid-latitudes, the prevailing winds blow west to east; flying eastbound gets a tailwind while the return leg faces a headwind.
How accurate are the estimates?
Typically within 10-20 minutes of scheduled block times, but airspace, traffic, and weather can cause larger deviations.
Is my data kept private when I use these everyday tools?
Yes. Whether it's a word count or a time-between-dates check, nothing is sent to a server. The page does the counting locally — you can paste a draft, get 1,242 words and 6 min reading time, and close it without a trace.
Do I need internet after the first load?
Not really. Once cached, word-counter, hours, fuel-cost and the rest work offline. Handy if you're drafting on a train or counting hours on site without signal — load once, use anywhere.
What's the fastest way to share a result?
'Share Link' does it. It encodes your inputs in the address bar, so the other person sees the exact same hours (e.g. 09:15 to 17:45 = 8h 30m) without you retyping.