how much does it cost to mail an envelope that weighs 1 oz

A standard 1 oz letter costs $0.78 to mail with a USPS Forever stamp. If the envelope is nonstandard — for example, square, rigid, or unusually shaped — it can cost more, starting at $1.27 or more depending on the mailpiece.

What to expect

• Regular letter, 1 oz: $0.78.

• Postcard: $0.61.

• Large envelope/flat, 1 oz: $1.63.

• Nonmachinable letter: extra charges may apply for unusual shapes or contents.

Example

A normal business-size envelope with one sheet of paper usually falls under the $0.78 letter rate.

Bottom line

For most regular 1 oz envelopes, plan on one Forever stamp.