How much does it cost to mail a 6 ounce letter?

As of my last update, the cost to mail a 6-ounce letter within the United States using First-Class Mail is typically based on the weight and size of the letter. For a letter weighing more than 1 ounce, the price increases incrementally. You would need to check the current USPS rates for the exact cost, which can vary based on factors such as destination and service type.