 <p>there is a good example in here to calculate distance with PHP <a href="http://www.geodatasource.com/developers/php" rel="nofollow">http://www.geodatasource.com/developers/php</a> :</p> <pre><code> function distance($lat1, $lon1, $lat2, $lon2, $unit) { $theta = $lon1 - $lon2; $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) + cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta)); $dist = acos($dist); $dist = rad2deg($dist); $miles = $dist * 60 * 1.1515; $unit = strtoupper($unit); if ($unit == "K") { return ($miles * 1.609344); } else if ($unit == "N") { return ($miles * 0.8684); } else { return $miles; } } </code></pre>