eShop Shipping Rates

I have set my shipping to Method 4 (weight & zone). I set my country as US and selected all for State. My question is this do I physically have to enter the weight and rate per zone? I was hoping that it would generate automatically. Is there a plugin that will allow the user to enter the weight and zip code and it automatically will generate the shipping rate for either US postal service, UPS, & Fed Ex? I am selling books, DVDs, etc.