To determine what size flush mount light is appropriate for your space, consider the height and width of the room. As a general rule of thumb: For rooms with ceilings under 8 feet tall – consider fixtures that are less than 12 inches wide. For rooms with ceilings between 8-10 feet tall – look for fixtures around 16-20 inches wide. For rooms with ceilings taller than 10 feet – opt for larger fixtures that are over 24 inches wide. Remember that these are just guidelines; ultimately, you should choose a fixture size that looks proportionate to your room and fits well with your decor style.