The standard height for pendant lights over a kitchen island is 30 inches above the surface of the island, or 60-66 inches from the ceiling. The primary measurement concern when hanging pendant lights is the space between the island and the lights, so it is more accurate to measure up from either the countertop or the floor rather than down from the ceiling.
However, there are a few other factors to consider when hanging pendant lights. If the ceiling is more than 8 feet tall, the light will disperse throughout the room more evenly if the installer increases the height of the pendant lights 3 inches for every extra foot of ceiling height. It is also a good idea to keep tall family members in mind when hanging pendant lights. Raise the lights a few extra inches to allow for more head room if there will be taller people using the island.