BYTETOOLS

Great Circle Path Generator

Sample the great circle between two coordinates into waypoints and export it as a GeoJSON LineString, KML or CSV, split at the antimeridian.

Start point

End point

20
3974.21
Distance (km)
2145.90
Distance (nmi)
65.9°
Initial bearing
40.786°
Highest latitude

Path on an equirectangular grid

Plain lat/lon graticule with 30° gridlines — no map tiles are loaded. The curve bows away from the straight line because a great circle is the shortest path on a globe, not on a flat map.

GeoJSON (20 points)

Path summary

Great-circle distance
3974.211 km · 2469.460 mi · 2145.902 nmi
Bearings
65.87° ENE at the start, arriving on 93.84°
Latitude range along the path
33.9425° to 40.7861°
Spacing between points
209.169 km

What is the Great Circle Path Generator?

A straight line on a flat map is not the shortest route on a globe. This generator samples the true great circle between two points using spherical linear interpolation on the unit vectors, so the exported line follows the path an aircraft or ship would actually take and bends toward the pole exactly as it should.

  • True great-circle sampling with the spherical interpolation formula, not a straight map line
  • 2 to 200 points along the path, with the spacing between them reported
  • GeoJSON LineString, KML and CSV export, plus adjustable coordinate precision
  • Automatic antimeridian splitting into a MultiLineString so the render is correct
  • Distance, initial and arrival bearings and the highest latitude reached
  • Canvas preview drawn from your data — no map tiles, no network, no uploads

How to use the Great Circle Path Generator

  1. 1

    Enter the start and end coordinates in decimal degrees or DMS.

  2. 2

    Drag the slider to choose how many points to sample along the path.

  3. 3

    Pick an export format — GeoJSON LineString, KML or a CSV of waypoints.

  4. 4

    Set the coordinate precision, then check the sketch and the path summary.

  5. 5

    Copy the output or download it as a file.

About the Great Circle Path Generator

A straight line on a flat map is not the shortest route on a globe. This generator samples the true great circle between two points using spherical linear interpolation on the unit vectors, so the exported line follows the path an aircraft or ship would actually take and bends toward the pole exactly as it should.

Choose how many points to place along the path — from a two-point line to two hundred waypoints — and export the result as a GeoJSON LineString, a KML placemark or a CSV of waypoints with running distance and bearing. Paths that cross the antimeridian are split into two segments at 180 degrees so they render correctly instead of drawing a wrong-way line right across the map.

The preview is a plain latitude/longitude graticule drawn on a canvas from your own coordinates — there is no map tile layer, nothing is fetched, and nothing is uploaded. Everything is computed in your browser.

Frequently asked questions

Why does the great circle look curved on a map?

Because the map is flat and the Earth is not. On a Mercator or equirectangular projection the shortest path between two distant points appears to bow toward the nearer pole. That curve is the straight line — it only looks bent because the projection stretches the surface unevenly.

How many points should I generate?

For a short path a handful is plenty. For an intercontinental route, twenty to fifty points keeps the rendered line visibly smooth in any mapping software. More points only matter if you are going to measure or animate along the line rather than just draw it.

What happens when the path crosses the antimeridian?

The tool detects the longitude jump from about +180 to -180 and splits the line there, inserting a vertex at exactly 180 degrees in both segments. Without that split, most renderers draw a horizontal line all the way back across the map, which is the classic broken-flight-path bug.

Is this the same as a rhumb line?

No. A great circle is the shortest route but its compass bearing changes continuously along the way. A rhumb line holds one constant bearing and is easier to steer, but it is longer — sometimes considerably longer on a high-latitude crossing.

Which Earth model does the distance use?

A sphere of radius 6,371,008.8 metres, the IUGG mean radius, with the haversine formula. That is accurate to roughly half a percent against a full ellipsoidal calculation, which is well inside the precision anyone needs for drawing a flight path.

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