Question:
What is the actual halacha on covering your legs?
Answer:
The principle halachah is that the thigh must be covered, up to and including the knee. This is the ruling given by the Mishnah Berurah (75:2), and many follow his ruling. In a practical sense, the skirt must be several centimeters lower than the knee, to ensure that it is covered at all times.
However, other authorities (including the Chazon Ish 16:8) write that the “shok” of the Gemara is not the thigh, but the leg beneath the knee, reaching down to the ankle.
According to these opinions, the entire leg, down to the ankle, should be covered. However, there is no obligation to cover the entire leg with a skirt or dress, and for the area beneath the knee it is sufficient to wear tights.
Beyond these basic guidelines, the halachah depends on the custom of the place in which a person lives. If it is the custom to cover a certain area (say, the feet), it would be part of the halachah to cover the area.
Best wishes.
