First, create a new PHP file. For example: test.php

Put these codes inside the file:

<?php
$absolutePath = realpath
(dirname(__FILE__));
echo $absolutePath;
?>

Save it, and then upload it to the folder you want to find the absolute path of.

Type the address of the file you just uploaded. For example:
http://yoursite.com/test.php

And you will get something like this:
/home/username/public_html/folder

That’s all there is to it.