Best Answer: You can safely send four sheets of regular-weight paper and an envelope for 39c (one ounce rate). If the paper is thin, maybe five. If you go over that number, you need an extra 24c in postage for each five sheets. It doesn't matter how many stamps you use if the total value is correct. If you get so many sheets that you need a larger (clasp-type) envelope, then better take it to the post office to be weighed, as those clasp envelopes can be pretty heavy.