There are many postal companies that provide real time rate lookups. LiveCart makes it easy to add support for additional shipping companies.
NOTE: It is also possible to define shipping rates manually.
Each shipping rate calculator plugin must extend the ShippingRateCalculator class and implement the following methods:
To install the plugin, simply copy it's file to the /library/shipping/methods directory. The file name must be identical to the class name. For example, if your class is named FedexCalculator, the file name must be FedexCalculator.php.