The PHP Shipping Rates Calculator is a series of PHP functions that enable your web application to retrieve exact realtime shipping rates from UPS, US Mail, and FedEx shipping carriers. These functions streamline the development of a web based shipping application or shopping cart written in PHP. The PHP Shipping Rates Calculator will be working within minutes of uploading to any server running PHP 4.3+ or PHP 5.x with cURL support configured and installed. Simply call the function from the checkout page of your existing shopping cart or anywhere within your system and the rates will be returned. The function requires weight, destination zip code, origin zip code, and desired carriers values to be passed to the function. Carrier, Service Name, Service Code, and Price values are all returned in an associative array.