On This Page
- Four numbers for any two airports
- Why routes curve, and why real ones run longer
- How the time and CO₂ estimates are built
- Five long-haul routes, calculated
- Time zones and the date line
- How the calculator is verified
- FAQ
Four Numbers for Any Two Airports
Type a city, airport name or three-letter IATA code (LHR, JFK, DXB) into each box and pick from the list. The calculator returns the great-circle distance in km, miles and nautical miles, an estimated block time, CO₂ per economy passenger, and the time difference between the two cities. The swap button reverses the route. Everything runs in your browser, and around 250 major airports are included.
Why Routes Curve, and Why Real Ones Run Longer
The shortest path between two points on a sphere is an arc of a great circle, one centered on the Earth's middle. That is why London–Los Angeles flights arc up over Greenland: a flat map makes the straight line look like the short way, but the globe says otherwise. The calculator uses the haversine formula with an Earth radius of 6,371 km, treating the Earth as a sphere, which is within about 0.5% of reality.
The route actually flown is usually 2 to 8% longer, because of departure and arrival procedures, oceanic track systems, restricted airspace and winds. Treat the great-circle figure as the clean baseline for planning. One kilometer is 0.621 statute miles or 0.540 nautical miles.
How the Time and CO₂ Estimates Are Built
Block time is the distance at a 900 km/h cruise plus a fixed allowance for taxi, climb and descent. CO₂ is the distance times a per-passenger factor that includes the extra warming effect of emissions at altitude:
| Distance | Time allowance added | CO₂ factor (economy, one way) |
|---|---|---|
| Under 1,500 km | 45 min | 0.255 kg per km |
| 1,500 – 4,000 km | 60 min | 0.195 kg per km |
| 4,000 – 6,000 km | 60 min | 0.145 kg per km |
| Over 6,000 km | 90 min | 0.145 kg per km |
Short flights cost more CO₂ per km because climbing, the thirstiest part of any flight, is a bigger share of the trip. Business class is roughly 1.5 to 2.5 times the economy figure and first class 2.5 to 4 times, because the seats take up more of the cabin. Published airline schedules can differ from these estimates because of winds, traffic control and airport slots. If driving is an option on a shorter route, the Fuel Efficiency Calculator estimates the fuel for the same distance by car.
Five Long-Haul Routes, Calculated
| Route | Distance | Est. block time | CO₂ per passenger |
|---|---|---|---|
| London (LHR) – New York (JFK) | 5,540 km / 3,442 mi | 7 h 9 min | 803 kg |
| Dubai (DXB) – Sydney (SYD) | 12,044 km / 7,484 mi | 14 h 53 min | 1,746 kg |
| Paris (CDG) – Singapore (SIN) | 10,723 km / 6,663 mi | 13 h 25 min | 1,555 kg |
| Johannesburg (JNB) – London (LHR) | 9,075 km / 5,639 mi | 11 h 35 min | 1,316 kg |
| Los Angeles (LAX) – Tokyo (NRT) | 8,753 km / 5,439 mi | 11 h 14 min | 1,269 kg |
The transatlantic figure is about what a petrol car emits over 5,000 to 6,000 km. Real schedules vary with the wind: westbound Pacific and Atlantic flights often take an hour or more longer than eastbound ones because they fly into the jet stream.
Time Zones and the Date Line
The time difference comes from your device's clock and the IANA time zone database, so it follows daylight saving automatically. Seasonal shifts change the gaps: Tokyo is 16 hours ahead of Los Angeles in summer and 17 in winter, Sydney is 6 or 7 hours ahead of Dubai, and London is 1 hour behind Johannesburg in summer and 2 in winter. Some zones are offset by fractions of an hour, such as India (UTC+5:30), Iran (UTC+3:30) and Nepal (UTC+5:45); the Time to Decimal Calculator turns those into decimal hours. Flying west across the International Date Line skips a calendar day: leave Los Angeles on a Monday evening and you land in Sydney on Wednesday. To add flight time to a working shift across zones, use the Work Hours Calculator.
How the Calculator Is Verified
Pick any two airports and the calculator pulls their stored latitude and longitude, converts both to radians, and runs them through the haversine formula (d = 2R x arctan2(sqrt(a), sqrt(1-a)), with R fixed at 6,371 km) to get the great-circle arc between them. That is the same curved-path math behind long-haul routes like London to Los Angeles arcing up over Greenland instead of tracking a straight line across a flat map projection. Swapping the origin and destination produces the same distance either way, since the formula treats both points symmetrically.
Frequently Asked Questions
Why does my flight take longer westbound than eastbound?
The jet stream is a fast-moving band of air at cruise altitude that blows predominantly from west to east at 100 to 250 km/h. Eastbound aircraft ride this tailwind and arrive faster. Westbound aircraft fly against it, adding time. The effect is most pronounced on transatlantic routes and can mean a difference of 1 to 2 hours each way.
How do I calculate flight distance for a compensation claim?
Under EU Regulation 261/2004, compensation for delays and cancellations is banded by flight distance. Flights up to 1,500 km qualify for €250 per passenger. Flights between 1,500 and 3,500 km qualify for €400. Flights over 3,500 km qualify for €600. To calculate flight distance for a compensation claim, use the great-circle distance between the departure airport and the final destination airport as listed on your ticket, not any intermediate stop on a connecting itinerary. Airlines sometimes dispute compensation on routes close to a threshold, so an independent calculation using the departure and arrival coordinates is useful supporting evidence. This flight distance calculator gives the direct distance between any two airports in kilometers, which is the figure airlines and dispute resolution services use for EU261 assessments.
What is crow flight distance and how does it differ from road distance?
Crow flight distance, also called as-the-crow-flies distance or straight-line distance, is the shortest possible path between two points on the Earth's surface without following roads, rivers, or other infrastructure. It is equivalent to great-circle distance on a sphere. Flight distance between airports is essentially crow flight distance: aircraft follow routes as close to the direct path as air traffic control and weather allow. Road distance is always longer because roads must follow terrain, cross bridges, and navigate built-up areas. For continental routes, road distance is typically 1.2 to 1.4 times the crow flight distance. For routes that cross large bodies of water or mountain ranges, the ratio is much higher. Use the Distance Calculator with latitude and longitude coordinates to calculate crow flight distance between any two specific points, not just airports.
Is this the same as an air miles calculator?
It depends which "air miles" you mean. If you want the actual flight distance in miles (or km/nautical miles), this is exactly that: an air miles calculator in the literal sense, distance through the air between two airports. If you are instead asking about frequent-flyer reward points, sometimes also called "air miles" (for example the Air Miles loyalty program), that is a different concept this calculator does not cover: reward miles are set by each airline or program and often do not match the physical distance flown at all. This tool only calculates real great-circle distance, flight time, and CO₂.
References
- ICAO Carbon Emissions Calculator Methodology: the International Civil Aviation Organization's framework for per-passenger CO₂ estimation including radiative forcing factors.
- Great-circle distance, Wikipedia: derivation and properties of the Haversine formula for spherical geometry.
- OurAirports data: open airport database providing IATA codes, coordinates, and timezone references for airports worldwide.