A piano keyboard height measured from the floor to the top of the white keys will approximate 28 1/2 inches. This is typically well adjusted for the average adult player.
Children learning to play may have difficulty adjusting to the height and therefore are advised to use a cushion to raise themselves to the proper height.
The proper piano keyboard height will be indicated by the displacement of the forearm and arm of the piano player. Essentially the forearm must be perpendicular to the piano and the arm must be parallel to the piano in other words the the arm and forearm must be at 90 degrees when the hands are resting on the piano. The wrist and forearm must always always form a straight line.
If proper placement of the arm and forearm is not achieved then there is the potential for muscle spasms not only in the arm and forearm but also the fingers and could lead to severe and chronic pain.
The distance that a student sits from a piano should allow free movement of the arm and fingers but not to the extent that one’s shoulders are forced upwards during play.
Most teachers teach children the C scale because it is the easiest to learn. Teachers tend to focus on the child’s ability to learn by introducing scales that are easy from the perspective of the child’s intellectual capacity at that time.
However, this is one of the most difficult scales to learn physically because the nature of the scale does not lend itself well to the physical movement of the fingers on the piano because none of the black notes are involved.
It would be much easier for teachers to allow the student to learn other scales such as the B scale. This is less demanding physically than learning the C scale albeit it is intellectually demanding. Is a well-known fact that digital pianos and electronic keyboards contribute more to finger stress and damage than a natural acoustic piano.
Although it doesn’t seem to be intuitive it can be explained in this manner. When playing an acoustic piano striking the keys harder will result in a louder sound. Unlike the acoustic piano striking the keys on a digital piano does not result in a larger volume. But while playing a digital piano in the heat of the moment one will instinctively attempt to strike the keys harder in an effort to play louder.
This action will result in the fingers being much stiffer which can lead to eventual stress and pain in the fingers. As a musician one must be cautious and aware of this phenomenon.
Video Overview of Proper Distance and Height from the Keyboard