usps - how many ounces can i mail first class
What is First Class Mail? Printing First Class Mail on NetStamps. First Class Mail is the most popular and economical way to send items through USPS. You can send standard postcards, letters and large envelopes and small packages up to 15.99 ounces using First Class Mail. If your First Class package is over 15.99 ounces, you must upgrade the mail class to Priority Mail. While there are no guaranteed delivery times for First Class Mail, letters or packages typically take two to three days to arrive at their final destination in the U.S.