To mail an envelope weighing 1.5 ounces in the United States, you typically need two first-class stamps. The first stamp covers the base rate for up to 1 ounce, and the second stamp accounts for the additional weight. Always check the current postal rates, as they can change.
how many stamps for a 3.4oz envelope
I think you mean 9x12 envelope.
A 4-ounce large envelope currently costs $1.57.
I successfully mail CDs all the time with 2 stamps.
As of June 10, one ounce of first class mail is 44¢. Every additional ounce is 20¢. So, a six ounce envelope would cost $1.44 to mail, or four forever stamps.
That depends on where you are sending it from (you country of origin) and to (the country of destination).
It depends on how heavy the contents are and how big the envelope is.
It depends on the weight It depends on the weight
3
Take your envelope to the Post Office and they will weight it, and give you your answer as the cost of mailing anything is done by weight.
how many stamps for a 10.4 ounce envelope
As many as will fit. I have one envelope in my collection with 44 stamps on it! The sender used one cent stamps to mail it. Some people will overlap stamps to get more to fit, which is okay as long as the Post Office can plainly see that they are all there.