A letter that weighs over 3.5 oz is classified as what?

A letter that weighs over 3.5 ounces is classified as a Flat. This classification is important because it indicates that the item exceeds the weight limit for standard letters in the First-Class mail category, which is typically a maximum of 1 ounce for regular pricing.

When a letter's weight surpasses this limit, it can no longer be processed as a standard letter and must be treated differently. Flats are essentially larger, thicker, or heavier pieces of mail that can include items like large envelopes or magazines. The Flat classification allows for more options in handling and delivery but also comes with different pricing and service standards compared to First-Class letters.

Understanding these categories is crucial for correct postage application and ensuring that mail items are sent in compliance with USPS regulations, thus preventing delays or additional charges. The confusion sometimes arises with parcels, which are typically defined as packages, often larger or thicker than flats, and will have different weight restrictions and handling procedures.