calculated calculator calulated charged correctly cost entered fix international mail order packaging paypal priority products ship shipping usps weight

The shipping cost for this order was not calulated correctly. Can you please tell me why and how we can fix it?
The shipping cost charged to the order was $9.30 when Paypal/USPS charged us $18.76 to ship it.

The shipping is calculated based on the packaging and products weight you have entered. If you are using our USPS calculator, then the shipping is calculated for "International Priority" mail.