Plug two cities into different travel tools and you'll get three different answers: a straight-line distance, a driving time, and a flight time. They're all "correct" — they just measure different things. Understanding the difference helps you plan smarter.
Straight-Line Distance ("As the Crow Flies")
This is the shortest possible distance between two points, measured in a straight line across the Earth's surface. It's calculated using the haversine formula, which accounts for the planet's curvature. It's the baseline number — but you can almost never actually travel in a perfect straight line.
Driving Distance & Time
Roads don't run in straight lines — they curve around mountains, follow coastlines, and connect through towns. Actual driving distance is therefore always longer than the straight-line distance, typically by 20–40%. Driving time then depends on that road distance plus average speeds, traffic, and stops.
Flight Time
Flights travel much closer to the straight-line distance (great-circle routes), so the distance is shorter than driving — but flight time also includes climb, cruise, and descent, plus you must add airport time on both ends. A "two-hour flight" rarely means two hours door to door.
Which Number Should You Use?
- Comparing how far apart places are: straight-line distance.
- Planning a road trip: driving distance and time.
- Booking flights: flight time, plus 3–4 hours of airport and transfer time.
Frequently Asked Questions
Roads curve around terrain, follow coastlines, and route through towns rather than going in a straight line. This makes actual driving distance typically 20–40% longer than the straight-line ("as the crow flies") distance between two points.