Great Circle Route Generator

What this generator does

Computes the distance with the haversine formula, the bearings at both ends, and waypoints by spherical interpolation. Every waypoint is then re-measured against both endpoints to confirm it lies on the route.

How to use this tool

1. Enter the latitude and longitude of both ends.
2. Choose how many waypoints to compute.
3. Read the distance and the two bearings.
4. Compare the great circle against the constant-bearing distance.

Understanding the controls

From and to coordinates

Latitude between −90 and 90, longitude between −180 and 180. North and east are positive.

Waypoints

How many intermediate points to compute. They are evenly spaced by distance along the path, not by longitude.

Common use cases

• Working out the true distance between two coordinates
• Generating waypoints for a route or a map drawing
• Explaining why long flights take curved-looking paths
• Producing test coordinates for a mapping or geospatial tool
• Comparing a shortest route against one you can actually steer

How this generator works

The haversine formula gives the distance across a sphere from the two latitudes and the difference in longitude, staying accurate even for very short distances where the simpler formulas lose precision. Waypoints come from spherical interpolation, which walks along the great circle itself rather than along a straight line in latitude and longitude. Before display each waypoint is checked by measuring both legs through it and confirming they sum to the whole distance, the legs are summed end to end, and the constant-bearing route is confirmed never to be shorter.

Randomness and fairness

Nothing here is random. Two coordinates give exactly one great-circle route.

For how randomness is produced across the whole site, see how Generate Random works.

Limitations and good to know

• The Earth is treated as a sphere, so distances are out by up to about half a percent against the true ellipsoid — Vincenty's formulae do better if that matters.
• Altitude is ignored entirely, so this is distance over the surface rather than a flight path.
• Antipodal points have no unique great circle, and the route through them is arbitrary.
• No terrain, airspace or shipping lane is considered: this is geometry, not navigation.

Privacy and your data

The route is computed in your browser. The coordinates you enter are never transmitted, stored or included in analytics.