How to use it
- Add two or more places: search, use your location, or click the map.
- Read the midpoint, the nearest town to it, and the distance from each place.
- Copy the link to share the meeting point.
5 practical uses
- Pick a fair place to meet a friend who lives across town.
- Find a venue between several offices or families.
- Plan a halfway stop on a long drive.
- Find the centre of a group of homes for a car pool.
- Locate the midpoint of a flight or a sea crossing.
The maths behind it
For two points the midpoint on the great circle is φ = atan2(sin φ₁ + sin φ₂, √((cos φ₁ + Bₓ)² + Bᵧ²)), with Bₓ = cos φ₂ cos Δλ and Bᵧ = cos φ₂ sin Δλ. For more points each is converted to a unit vector, the vectors are averaged, and the average is converted back to latitude and longitude: the geographic centre, or centre of gravity, of the points.
Which middle
For two places the midpoint is the point halfway along the shortest path between them over the surface of the Earth. For more, it is the geographic centre: the point that balances them all, found by averaging their positions in three dimensions and projecting back onto the sphere. That is the centre of gravity, not the point with equal travel time; someone on their own far to the east pulls the middle towards them less than a road-based "fair meeting point" would.
The nearest town comes from GeoNames places with 5,000 or more people, with the distance from the midpoint.