Wikipedia says cats always land on their feet if they fall from at least a foot high. If they fall only a few inches, they don't have time to turn to be feet down before they hit the ground.

The Wikipedia article is called "cat righting reflex" and it says this:
The cat righting reflex is a cat's innate ability to orient itself as it falls in order to land on its feet. The righting reflex begins to appear at 3–4 weeks of age, and is perfected at 6–7 weeks.

Cats are able to do this because they have an unusually flexible backbone and no functional clavicle (collarbone).

Thanks for your question. It's fun to know the answer.