Midpoint Calculator - Free Online Tool

Calculate your midpoint with our free online tool.

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How This Tool Works

This calculator finds the geographic midpoint between two latitude and longitude coordinates along the great-circle path. It converts both input points from degrees to radians, treats them as points on the Earth's surface, and calculates the halfway point on the curved route rather than averaging the displayed coordinates.

Enter Point A and Point B as decimal degrees. Valid latitude values run from -90 to 90, and valid longitude values run from -180 to 180. The result shows the midpoint coordinates plus the distance from each endpoint, so you can confirm the midpoint is equidistant along the route.

  • Input: Two latitude/longitude coordinate pairs.
  • Method: Great-circle midpoint on a spherical Earth model.
  • Output: Decimal-degree midpoint and distances in kilometers.

Why This Matters

For real-world coordinates, simply averaging latitude and longitude can place the midpoint in the wrong location because Earth is curved and longitude spacing changes with latitude. A great-circle midpoint better represents the halfway point along the shortest surface path.

This is useful for flight planning, approximate rendezvous points, route analysis, and comparing two locations on a map.

Common Mistakes to Avoid

  • Do not use planar x/y midpoint formulas for GPS coordinates: averaging coordinates can be misleading over long distances.
  • Keep signs correct: south latitudes and west longitudes should be entered as negative values.
  • Stay within coordinate bounds: latitude must be between -90 and 90, and longitude must be between -180 and 180.

Frequently Asked Questions

Common questions about the Midpoint Calculator - Free Online Tool

This converter handles decimal degrees, degrees-minutes-seconds (DMS), UTM, MGRS, and other common geographic coordinate systems used in mapping and navigation.
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Sources & References

Geographic coordinate systems

Latitude/longitude, UTM, and datum definitions underlying coordinate conversions.