PHP Get the Distance Between Two Lat/Lng Points

If your building some custom Google Maps and need to get the distance between two points I got the Math done for ya.

<?php
/**
	* Return a distance between two lat/lng points
	*
	* @param int $lat1         REQUIRED; Latitude - Location 1
	* @param int $lon1         REQUIRED; Longitude - Location 1
	* @param int $lat2         REQUIRED; Latitude - Location 2
	* @param int $lon2         REQUIRED; Longitude - Location 2
	* @param string $unit      OPTIONAL; Distance Type (Km / M)
	* @return int
	*/
	function getDistance($lat1, $lon1, $lat2, $lon2, $unit) {
	 if($lat1 == $lat2 &amp;&amp; $lon1 == $lon2)
	   return 0;

	 $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;
	 }
	}
?>

The function below will return the distance between two Lat/Lng points so for you to use in your code to calculate travel fees or just the distance in miles/kilometers. This is a very handy bit of code.

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