In general, there should be 6-ft between the floor and the bottom of pendants should hang between 12 and 20 inches below the ceiling if they are in a room with 8-foot ceilings. This will give enough clearance between the floor and the pendant.
Over dining tables or kitchen islands, pendants should hang about 30 to 36 inches above the countertop surface. This is a perfect height for illuminating your dinner table while being high enough not to disturb anyone.
Over kitchen islands, pendants should be about 24 to 30 inches apart from one another. This is measured from the center of one fixture to the center of the next.
Over a dining room or kitchen table, the placement of pendants depends on your preferences of the space.