Using PHP and google Maps Api to work out distance between 2 post codes (UK)

Assuming you are looking for the geographic distance, first you need to get the latitude and longitude of your two postcodes with the Google Maps server-side geocoding services as in the following example:

$url = 'http://maps.google.com/maps/geo?q=EC3M,+UK&output=csv&sensor=false';

$data = @file_get_contents($url);

$result = explode(",", $data);

echo $result[0]; // status code
echo $result[1]; // accuracy
echo $result[2]; // latitude
echo $result[3]; // longitude

Then you can calculate the distance between the coordinates of your two postcodes by using a great-circle distance implementation such as the following:

• Snipplr - Calculate distance between two coordinates in PHP

Note that the server-side geocoding service may only be used in conjunction with displaying results on a Google map; geocoding results without displaying them on a map is prohibited by the Google Maps API Terms of Service License Restrictions.

UPDATE:

If you are looking for the driving distance instead of the geographical distance, note that there is no documented and approved method at the moment to access the Google Maps Directions API via an HTTP request on the server-side.

Nevertheless, an undocumented method that returns a JSON output is the following:

http://maps.google.com/maps/nav?q=from:London%20to:Dover

This will return you the driving directions, along with the total driving distance in JSON format: "meters":122977.

The format of the q parameter should be from:xxx%20to:yyy. Replace xxx and yyy with the start and destination respectively. You can use latitude and a longitude coordinates instead of full addresses:

http://maps.google.com/maps/nav?q=from:51.519894,-0.105667%20to:51.129079,1.306925

Note that not only this is undocumented, but it may also violate the restrictions 10.1 and 10.5 of the Google Maps API Terms and Conditions.

You may also be interesting in checking out the following related articles:

• Stack Overflow: Calculate driving directions using PHP?
• Getting distance using GDirections via URL
• Retrieve driving directions from google maps with server-side HTTP calls and show results with static maps for WAP
• Google Maps and Directions, REST Interface?

Don't know if the V3 API changes anything, but I've been using this for quite a while and it still works:

From and to are each expressed as latitude,longitude (an address would probably work; I'm sure I tried it but don't remember and I had the coordinates anyway)

$base_url = 'http://maps.googleapis.com/maps/api/directions/xml?sensor=false';
$xml = simplexml_load_file("$base_url&origin=$from&destination=$to");
$distance = (string)$xml->route->leg->distance->text;
$duration = (string)$xml->route->leg->duration->text

Building on Daniel's answer, you can use Google's Geocoding API to get car, public transport, walking and cycling distances easily :

$postcode1='W1J0DB';
$postcode2='W23UW';
$result = array();

$url = "http://maps.googleapis.com/maps/api/distancematrix/json?origins=$postcode1&destinations=$postcode2&mode=bicycling&language=en-EN&sensor=false";

$data = @file_get_contents($url);

$result = json_decode($data, true);
print_r($result);

Be sure to replace &mode=bicycling with your preferred parameter:

• &mode=driving
• &mode=bicycling
• &mode=transit
• &mode=walking