What is the difference between butter and low fat butter?

Low-fat butter is processed in the same way as regular butter. While regular butter is required to have at least 80 % milk fat content, ‘reduced-fat’ (three-quarter-fat) butter is required to contain 60-62 % milk fat and low-fat (half-fat) butter is required to contain 39-41 % milk fat.

A typical 10 g serving of regular butter contains approximately 72 kcal and 8 g fat, whereas a typical 10 g serving of low-fat butter contains approximately 38 kcal and 4 g fat.