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How to Calculate the Distance Between Two Lat/Longs

Determining the distance between latitude-longitude points is not as straightforward as calculating the distance between XY points because the distance between lines of longitude varies with latitude. The haversine formula for great-circle distances is generally used for this calculation.

Calculate Latitutde-Longitude Difference
- Convert all latitude and longitude values to radians. Calculate the difference in latitude (DLAT) and longitude (DLONG) between the two points:
  
  DLAT = latitude1 - latitude2
  
  DLONG = longitude1 - longitude 2
Interim Calculation Step 1
- Calculate the value of an intermediate value A with the following formula:
  
  A = sin(DLAT / 2)^2 + cos(latitude1) * cos(latitude2) * sin(DLONG / 2)^2
  
  "Sin" and "cos" are the trigonometric functions sine and cosine and the caret (^) indicates raising to a power.
Interim Calculation Step 2
- Calculate the value of an intermediate variable C by the following formula:
  
  C = 2 * (atan2(A^0.5, (1-A)^0.5))
  
  Atan2 is the trigonometric function arctangent.
Calculate Distance
- Multiply the intermediate value C by the radius of the Earth (6,371 km or 3,959 miles) to obtain the shortest distance between the two points.

Nature