Get distance in KM between 2 coordinators in PHP

php_distance_between_2_coords.php

<?php

function distanceBetweenCoords($lat1, $lon1, $lat2, $lon2) {

    $lat1 = deg2rad($lat1);
    $lat2 = deg2rad($lat2);
    $lon1 = deg2rad($lon1);
    $lon2 = deg2rad($lon2);

    $earthRadius = 6371;
    
    $adjust = 1.16; // adjust of 16% for better proximity to reality
    
    $dist = ($earthRadius * acos( cos($lat1) * cos($lat2) * cos($lon2 - $lon1) + sin($lat1) * sin($lat2) ) );
    $dist *= $adjust;

    return $dist;
}