How do I measure distance in Google Earth for flight planning?
Measure distance in Google Earth for flight planning, use nautical miles, plot multi-leg routes, and understand why simulator totals may differ.
For aviation, real-world flying and flight-simulator planning, use Google Earth's Measure or Ruler tool, select nautical miles, then click the departure point and each waypoint in route order. The displayed total is a useful estimate, but verify it in an aviation planner because Google Earth does not account for airways, procedures, airspace or operational routing.
How to measure a flight route in Google Earth
Google Earth Pro on desktop calls the tool Ruler, while browser and mobile editions generally call it Measure. The underlying method is the same: create one segment for a direct route or a multi-point path for several legs.
- Locate the departure and destination. Search for each airport, coordinate or recognisable landmark. Zoom in far enough to place points consistently.
- Open the measurement tool. In Google Earth Pro, select Ruler from the toolbar or Tools menu and choose Line for one leg or Path for multiple legs. In other editions, select Measure and begin a path.
- Use an overhead view. Looking straight down does not change the globe calculation, but it makes accurate point placement much easier than clicking from a tilted view.
- Select nautical miles. Set the result to nautical miles, usually abbreviated NM or nmi. If that unit is unavailable, convert the displayed total using the figures below.
- Plot every intended waypoint. Click the departure point, each en-route fix or turning point, and the destination in order. Do not measure only airport to airport if you intend to fly an airway, departure, arrival or VFR route around controlled airspace.
- Read the complete path total. Check both the accumulated distance and individual legs where the edition provides them. Correct any point that was dropped beside rather than on its intended location.
- Rebuild and verify the route. Enter the same waypoints into an aviation flight planner or simulator and compare like with like: identical coordinates, endpoints and route legs.
If you also want to inspect terrain, landmarks and coordinates, our Google Earth Pro planning workflow explains where the application helps and where aviation-specific tools should take over.
Should flight-planning distance be measured in nautical miles?
Nautical miles are the standard unit for aviation route distance. They work directly with knots: an aircraft travelling at a groundspeed of 120 knots covers 120 nautical miles in one hour.
- 1 nautical mile equals exactly 1.852 kilometres.
- Kilometres to nautical miles: multiply by 0.539957.
- Statute miles to nautical miles: multiply by approximately 0.868976.
A visually plotted path does not justify excessive decimal precision. If the points were clicked from imagery rather than entered from published coordinates, rounding the result is more honest than treating every displayed tenth of a mile as exact.
Where should the measurement start and end?
The correct endpoints depend on the distance you are trying to calculate. Using different reference points is one of the main reasons Google Earth and a simulator show different totals.
- Airport-to-airport estimate: use each aerodrome's published reference coordinate or a consistent point near the airport centre.
- Runway-to-runway distance: use the relevant runway thresholds. This can differ noticeably from an airport-centre calculation.
- IFR route: plot the actual fixes from the departure, airway, arrival and approach rather than drawing a single direct line.
- VFR route: add every planned turning point, reporting point or landmark. Avoid tracing small visual curves that the aircraft will not actually follow.
Taxi distance is normally excluded from airborne route mileage. Likewise, if Google Earth offers terrain-following or 3D measurement, use the ordinary map-path distance for standard flight planning; terrain distance measures the surface rather than the aircraft's horizontal route.
Why does Google Earth disagree with my flight planner?
Distance totals disagree when the two tools are measuring different routes, endpoints or distance models. A small variation is normal; a large one usually indicates a missing procedure or a direct-versus-airway comparison.
| Cause | What happens | How to fix it |
|---|---|---|
| Different endpoints | One tool uses airport reference points while the other uses runways or the aircraft's present position. | Enter identical coordinates in both tools. |
| Direct line versus routed flight | Google Earth shows the shortest plotted path, while the planner includes airways, departures and arrivals. | Add every published route fix to the Google Earth path. |
| Turns, vectors and holds | Straight waypoint segments omit turn arcs, ATC vectors, holding and weather deviations. | Treat the result as planned track mileage, not guaranteed distance flown. |
| Rounding or data differences | Slightly different waypoint coordinates and calculation methods produce small discrepancies. | Use one navigation dataset for the final operational figure. |
| Terrain or 3D mode | The tool measures over the ground surface or between points in three dimensions. | Use the standard horizontal map path. |
A heading displayed by Google Earth should also be treated as a geographic or true bearing unless the tool explicitly states otherwise. It is not automatically a magnetic heading and does not include magnetic variation, wind correction or ATC routing.
Is Google Earth accurate enough for real-world flight planning?
Google Earth is suitable for preliminary route inspection, approximate distance and simulator planning, but it is not a sole operational source for real-world flying. Its imagery can be old or slightly misaligned, and it does not supply authoritative airspace, procedure, obstacle, weather, runway-status or NOTAM information.
For simulator routes, transfer the coordinates into a dedicated tool such as Little Navmap for route building and distance checks. Google Earth paths saved as KML or KMZ are not the same as a simulator's native flight-plan format, so rebuilding or converting the route may be necessary.
Microsoft Flight Simulator users should then compare the route against the waypoint legs and total shown by the MSFS flight planner. Keep the Google Earth measurement as a visual cross-check; use the aviation planner's navigation data for the route you will actually load and fly.