What is the minimum percentage of fat required for butter according to standards?

Butter must contain a minimum of 80% fat by weight according to the official standards established by regulatory bodies such as the U.S. Food and Drug Administration (FDA). This specific fat content is crucial because it ensures that butter maintains its characteristic texture, flavor, and cooking properties. The requirement helps to classify a product as butter rather than a margarine or spread, which can have varying fat contents. Meeting this minimum fat percentage also aligns with consumer expectations for a product marketed as butter, supporting its quality and performance in culinary applications.