According to USPS, “First-Class Mail Forever stamps cost $0.68 (the current 1 oz price) and will never expire, even if the First-Class postage rate goes up.” ...

The United States Postal Service (USPS) increased the price of first-class forever stamps by 5 cents on Sunday, July 13, moving from 73 cents to 78 cents. The higher stamp prices are now in effect ...