Lumens measure how much light you are getting from a bulb or fixture. More lumens mean it's a brighter light; fewer lumens mean it's a dimmer light.
Lumens let you buy the amount of light you want. So, when buying your new bulbs or LED fixtures, think lumens, not watts.
The brightness, or lumen levels, of the lights in your home may vary widely, so here's a rule of thumb:
To replace a 100 watt (W) incandescent bulb, look for a bulb that gives you about 1600 lumens. If you want something dimmer, go for less lumens; if you prefer brighter light, look for more lumens.
Replace a 75W bulb with an energy-saving bulb that gives you about 1100 lumens.
Replace a 60W bulb with an energy-saving bulb that gives you about 800 lumens.
Replace a 40W bulb with an energy-saving bulb that gives you about 450 lumens.