Fly or drive?
Fly or drive comparison
Assumptions & costs
Pick two cities to compare.
City coordinates from GeoNames, licensed CC BY 4.0. Top 2,000 cities by population.
Whether flying beats driving comes down to airport overhead. The plane is faster in the air at any distance, but three hours of check-in, security and getting to and from airports has to be paid first. Pick two cities above to see the straight-line distance, door-to-door flight time, driving time and fuel cost side by side.
How this is calculated
Distance is the great-circle distance — the shortest path over the surface of the earth — computed with the haversine formula shown above, using a mean earth radius of 6,371 km. Haversine rather than the simpler law of cosines because the latter loses precision on short distances, which is most of the pairs people try.
Everything downstream of that distance is an estimate with stated assumptions, all of them editable:
- Road distance is approximated as great-circle distance × a detour factor, 1.25 by default. This is not a routed distance. It is reasonable on average for developed road networks and clearly wrong where mountains, water or borders intervene.
- Flight time is distance ÷ cruise speed (500 mph default) plus airport overhead (3 hours default). It ignores wind, routing, taxi and holding, and assumes a direct flight exists.
- Driving time is road distance ÷ average speed (100 km/h default) with no stops, traffic or overnight breaks.
- Cost covers fuel only for driving — no tolls, parking or wear — and whatever airfare you enter.
The verdict needs flying to be at least 25% faster door to door before it recommends it. Below that margin the difference is smaller than the error in these assumptions, so it says the choice is close rather than inventing a winner.
No check is made for whether a road route exists. Ask for London to New York and you will get a driving time, because the calculation is arithmetic on a straight line rather than a route over actual roads. Treat any pair separated by an ocean, or by a border you cannot drive across, as flight-only regardless of what the driving column says.
City coordinates come from the GeoNames cities15000 dataset (CC BY 4.0), filtered to the 2,000 largest by population. This is deliberately one page and one tool: there are no generated city-pair pages, and there will not be.
Last reviewed:
Frequently asked questions
Is it faster to fly or drive?
It depends almost entirely on airport overhead. A flight is quicker in the air at any distance, but check-in, security, boarding and getting to and from airports add around three hours. Below roughly 400–500 km driving usually wins door to door; above about 1,000 km flying almost always does.
How is the flight time calculated?
Great-circle distance divided by cruise speed, plus your airport overhead. The default cruise speed of 500 mph is typical for a commercial jet, and it ignores wind, routing and holding, so treat it as an estimate.
Why is the driving distance longer than the distance shown?
The distance shown is the straight line over the earth. Roads are not straight, so the driving estimate multiplies it by a detour factor, 1.25 by default. Real road distance varies a lot with geography — mountains, water and borders all push it higher.
How accurate is this?
The distance is accurate. Everything built on it is a model: flight and driving times use fixed average speeds, and road distance is approximated rather than routed. Change the assumptions to match your own trip.
Does the cost comparison include everything?
No. Driving cost is fuel only — not tolls, parking, wear or accommodation on a long trip. Airfare is whatever you enter. Both are deliberately simple so you can see what goes into them.