What is the maximum weight for First-Class mail letters?

The maximum weight for First-Class mail letters is 3.5 ounces. This weight limit governs the classification of a letter in the First-Class mail category, ensuring that it remains eligible for the standard service rates associated with First-Class mail. Anything over this weight may require the mail piece to be classified differently, likely entailing higher postage costs or a different mailing service. Understanding these weight limits is essential for optimizing mailing strategies and costs in business communications. Knowledge of this weight restriction helps in choosing the correct mailing service based on the needs of the correspondence.