There are complex calculations that professionals like The Bulb Guys use to figure out how many lumens a space needs to be well lit. A good rule of thumb is that for a bedroom or any similar sized space, a fixture with three light bulbs will provide an adequate amount of ambient lighting. For an open concept living space that is a little larger, a fixture with five light bulbs would be more appropriate. Of course, The Bulb Guys are always here to help you figure that out