So here’s a quick couple snippets of code that will allow you to retrieve the coordinates of two locations using Google Maps API — no API key necessary.

This first function will return the coordinates of specific address (I find pretty much anything works, whether it’s a full address with street number, or just a postal code, or simply a city name) as an array of coordinates:

function getCoordinates($address) { $url = "http://maps.google.com/maps/geo?q=" . urlencode($address) . "&output=json"; $result = file_get_contents($url); $result = json_decode($result, 1); if (isset($result['Placemark'])) { list($lat, $long) = $result['Placemark'][0]['Point']['coordinates']; } else { $lat = $long = false; } return array($lat, $long); }

and the following function will accept the lat/long coordinates of two separate points and return their distance (not road/traveling distance, but straight-shot distance) in KM:

function calculateDistance($lat1, $long1, $lat2, $long2) { $R = 6371; // earth's mean radius in km $dLat = deg2rad($lat2-$lat1); $dLon = deg2rad($long2-$long1); $lat1 = deg2rad($lat1); $lat2 = deg2rad($lat2); $a = sin($dLat/2) * sin($dLat/2) + cos($lat1) * cos($lat2) * sin($dLon/2) * sin($dLon/2); $c = 2 * atan2(sqrt($a), sqrt(1-$a)); $d = $R * $c; // return distance in KM return $d; }

Now it certainly may be worthwhile to cache coordinates for a given location, depending on your usage, because retrieving the coordinates from Google for a large quantity of addresses at once can take some time.