Finding distances based on Latitude and Longitude

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This JavaScript uses the Haversine Formula (shown below) expressed in terms of a two-argument inverse tangent function to calculate the great circle distance between two points on the Earth. This is the method recommended for calculating short distances by Bob Chamberlain (rgc@jpl.nasa.gov) of Caltech and NASA's Jet Propulsion Laboratory as described on the U.S. Census Bureau Web site.

dlon = lon2 - lon1
dlat = lat2 - lat1
a = (sin(dlat/2))^2 + cos(lat1) * cos(lat2) * (sin(dlon/2))^2
c = 2 * atan2( sqrt(a), sqrt(1-a) )
d = R * c (where R is the radius of the Earth)

Note: this formula does not take into account the non-spheroidal (ellipsoidal) shape of the Earth. It will tend to overestimate trans-polar distances and underestimate trans-equatorial distances. The values used for the radius of the Earth (3961 miles & 6373 km) are optimized for locations around 39 degrees from the equator (roughly the Latitude of Washington, DC, USA).

Use LatLong.net to find the Latitude and Longitude for any U.S. address and DistanceFrom to find as-the-crow-flies distances. Also, I wrote a script to convert between decimal degrees and degrees/minutes/seconds formats.

First location (default: 1600 Pennsylvania Ave NW, Washington, DC)
Latitude: Longitude:
Expressed in decimal degrees

Second location (default: 1922 F St NW, Washington, DC)
Latitude: Longitude:
Expressed in decimal degrees

Results
miles
km