How much does cost to mail a letter in the US?

As of January 2022, the cost to mail a standard letter (1 oz or less) within the United States using First-Class Mail is $0.58. Additional ounces for letters cost $0.20 each. Rates may vary for larger envelopes, packages, or international mail. It is advisable to check the current postage rates with the United States Postal Service before sending mail to ensure accurate postage.