Yeah, didn't mean to be so formal. I also never in my life ever used the large envelope rate. That calculator should be programed, and a notice given, that you don't have to put in zip codes for first class mail items. Another thing that irks me is that you can't leave the pounds box blank; you must enter a zero (0). Finally, their calculator would be better if when you click "continue," you see your original settings on the page with the answers.
Robt.