What is the weight limit for first-class mail?

The weight limit for first-class mail is 13 ounces. This limit is important for distinguishing between different classes of mail. First-class mail provides expedited delivery and is typically used for letters, postcards, and small parcels that weigh up to this limit. Anything exceeding 13 ounces must be sent using another service category, such as Priority Mail, which offers different features and pricing. Knowing this limit is crucial for individuals and businesses sending mail, as it helps them choose the correct mailing option based on the weight and urgency of their items.