You might want to bookmark this for packages. Shows post office and UPS calculator on one page. Also has links to other USPS rates.
http://www.e-powersellers.com/shipping.htm
(I bet there is a web site someplace that lets you put in the info (zip codes, weights, etc) just once, and presto, lets you see the rates for different carriers. Nice to know where such a web site is.)
Robt.