In reality, cats possess the ability to turn themselves right side up in mid-air if they should fall upside-down, known as the cat righting reflex. This enables them to land on their feet if dropped from sufficient height, about 30 cm (12 in).⁽¹⁷⁾

Toast, being an inanimate object, lacks both the ability and the desire to right itself. Toast typically lands on the floor butter-side-down due to the manner in which it is typically dropped from a table. As the toast falls from the table, it rotates. Given the typical speed of rotation for a slice of toast as it falls from the table and the typical height of a table, a slice of toast that began butter-side-up on the table will land butter-side-down on the floor in 81% of cases.⁽¹⁸⁾

Cats can weigh between 2.8 kg (6.2 pounds) and 6.1 kg (13.4 pounds).⁽¹⁹⁾ A 25 g (0.9 oz) slice of bread⁽²⁰⁾ will have a negligible effect on the movement of the much larger cat.