Calculate the distance between two locations using PHP

In this article, we introduce a simple code to calculate the distance between two locations in PHP. For this, first we will get the latitude and longitude of both source and destination addresses in JSON format by sending request to google map geocode api. After that, we will calculate the distance between two locations from latitude and longitude in kilometer or miles.

This is the main file, that we will call on the browser. This file contains two input boxes to enter source and destination addresses and a selection option to select the unit. When the user clicks on the submit button, getRouteDistance() method will be called. This function calls the google api and gets the latitude and longitude of the entered addresses from json_encode and calculate the distance between them.

<!DOCTYPE html>
<html>
   <head>
       <title>Calculate the distance between two locations</title>
       <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" >
       <style type="text/css">
            .formbg { background-color: #66CCFF; padding: 10px 0 10px 20px; color: #191919;
                    border-radius: 10px;  border: 2px solid #6D0839; width: 780px; margin: 0 auto;
            }
	   label { font-size: 18px; }
	   h1 {color: #003366;}
       </style>
   </head>
   <body>
      <?php 
      function getRouteDistance($source_adrs, $dest_adrs, $unit){
          //Send request and receive json data
          $s_geocode = file_get_contents('http://maps.google.com/maps/api/geocode/json?address='.$source_adrs.'&sensor=false');
          $s_latlong = json_decode($s_geocode);
          $d_geocode = file_get_contents('http://maps.google.com/maps/api/geocode/json?address='.$dest_adrs.'&sensor=false');
          $d_latlong = json_decode($d_geocode);
          //Get latitude and longitude
          $lat1 = $s_latlong->results[0]->geometry->location->lat;
          $long1 = $s_latlong->results[0]->geometry->location->lng;
          $lat2 = $d_latlong->results[0]->geometry->location->lat;
          $long2 = $d_latlong->results[0]->geometry->location->lng;

          //Calculate distance from latitude and longitude
          $theta = $long1 - $long2;
          $dist = sin(deg2rad($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).' KM';
          } else {
              return $miles.' MI';
          }
      } 
      ?>
      <div class="form-group row formbg">
          <?php
          if(($_POST['source'] != '') && ($_POST['destination'] != '')) {
              $source = $_POST['source'];
              $destination = $_POST['destination'];
              $unit = $_POST['unit'];
              $source_adrs = str_replace(' ', '+', $source);
              $dest_adrs = str_replace(' ', '+', $destination);
              $distance = getRouteDistance($source_adrs, $dest_adrs, $unit);
              if($distance != '') {
                echo 'Distance Between <b>'.$source.'</b> and <b>'.$destination.' : </b><b>'.$distance.'</b>'
                    .'<br/><br/>';
              }
          }
          ?>
          <form action="" method="post">
             <div class="form-group row">
                <label class="col-xs-3 col-form-label">Enter Source Address: </label>
                <div class="col-xs-5">
                 <input class="form-control" type="text" name="source" value="" placeholder="Source">
                </div>
             </div>
             <div class="form-group row">
                <label class="col-xs-3 col-form-label">Enter Destination Address: </label>
                <div class="col-sm-5">
                 <input class="form-control" type="text" name="destination" value="" placeholder="Destination">
                </div>
              </div>
              <div class="form-group row">
                 <label class="col-xs-3 col-form-label">Unit: </label>
                 <div class="col-sm-5">
                  <select name="unit" class="form-control">
                      <option value="k">Kilometer</option>
                      <option value="m">Mile</option>
                  </select>
              </div>
             </div>
             <div class="form-group row">
                 <label class="col-xs-3 col-form-label"> </label>
                  <div class="col-sm-5">
                   <input class="btn btn-primary" type="submit" value="Submit"/>
                  </div>
                </div>
          </form>
      </div>
 </body>
</html>

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