Crow Flies Distance
Quick answer: Click two points on the map to get the straight-line distance between them — the great-circle distance, as the crow flies rather than along roads.
How to use as the crow flies distance
- Choose From and To using city search or latitude, longitude.
- Read both kilometres and miles below the map.
- Use the curved path for the great-circle route, then copy the numbers or download selected points.
Worked example
- Input
- New York → London
- Expected result
- About 5,570 km or 3,461 miles along the great circle.
This measures the shortest surface route. Airline itineraries, driving roads and a straight chord through the planet are different measurements.
Calculation method and accuracy
The haversine formula computes angular separation on a sphere, then multiplies it by mean Earth radius 6,371.0088 km. Longitudes are unwrapped for drawing so a route from 170°E to 170°W crosses the Pacific instead of spanning the entire map.
Common mistakes and edge cases
- Decimal places show resolution, not survey accuracy. An ellipsoidal model can differ by a few tenths of a percent.
- Driving distance includes roads and detours. Use a routing or drive-time tool for travel planning.
- A long route can look curved on a flat map while still being the shortest route on Earth.
Sources and verification
Reviewed by GeoDataViewer · . Examples are rounded; the interactive result uses your selected inputs.
What "as the crow flies" means
It means the shortest distance over the Earth's surface, following a great circle. A great circle is the largest circle that can be drawn on a sphere, and the arc of one between two points is the shortest route between them.
This is not the same as the straight line you would draw on a flat map. Mercator maps stretch distances, badly at high latitudes, so a ruler on a printed map gives the wrong answer for long distances.
Road distance is always longer
The gap between straight-line and road distance is the detour factor, and for road networks it is typically between 1.2 and 1.4. Islands and mountains push it much higher. Treat the crow-flies figure as a lower bound.
When straight-line distance is the right measure
Radio and line-of-sight planning, environmental and ecological studies, and any comparison between regions use straight-line distance, because the road network is not the subject. It is also the honest answer when you want to say how far apart two places are without implying a route.
Limitations to keep in mind
The distance is measured on a sphere using the mean Earth radius. Real terrain, altitude, and the ellipsoidal shape of the Earth introduce small differences, and the figure says nothing about how long it takes to travel.
Related tools
- Bearing calculatorCompass bearing from one point to another.
- Halfway pointThe great-circle midpoint between two places.
- Antipode finderThe point on the exact opposite side of the globe.
- Horizon distanceHow far you can see from a given height.
- Geographic centreThe centre of several points you pick.
Frequently asked questions
- What is crow-flies distance?
- The shortest distance between two points over the Earth's surface, following a great circle. It ignores roads, terrain, and any obstacle.
- Is it the same as great-circle distance?
- Yes. Crow-flies distance, great-circle distance, and as-the-crow-flies distance all mean the same measurement.
- How much longer is driving?
- Typically 20% to 40% longer on a road network. The ratio rises sharply for islands, mountain ranges, and places separated by water.
- Does the map show a straight line or a curve?
- A curve. The shortest path on a sphere appears curved on a flat map, especially for long routes. A straight line on a Mercator map is usually not the shortest route.
- Can it be shorter than the road distance?
- It is always shorter or equal. No road can be shorter than the straight line between its endpoints.
- What is the longest possible crow-flies distance on Earth?
- About 20,015 km, which is the distance from any point to its antipode, half the Earth's circumference.
- Is this accurate enough for legal or survey use?
- No. It is accurate to a few metres for a spherical model, but survey work needs an ellipsoidal calculation and a defined datum.
- Why does my calculation differ slightly from another tool?
- Different tools use different Earth radii. This one uses the mean radius of 6,371.0088 km, which is standard for great-circle work.
- Can I measure more than two points?
- This page measures a pair. For a chain of points, use the multi-stop route distance tool.
- Does altitude affect the distance?
- Not meaningfully. The difference between surface and flight-level distance is under 2% at cruising altitude, and irrelevant at ground level.