Output Watts of Compact Fluorescent Vs. Incandescent Lights

CFL bulbs use much less energy than incandescent bulbs.

The amount of light a light bulb produces is measured in lumens. The amount of energy a light bulb takes to produce light is measured in watts. Light bulb packages, including compact fluorescent lights (CFLs) and incandescent lights, list the bulb's lumens and watts.

Lumens

Both CFLs and incandescent lights come in a range of lumens. For example, a 60-watt incandescent bulb produces about 900 lumens, while a 100-watt incandescent bulb produces about 1,750 lumens.

Watts

Incandescent lights use three to four times as many watts as CFLs to produce the same amount of lumens. For example, an incandescent light bulb uses about 75 watts to produce 1,200 lumens, while a CFL uses only 20 watts to produce an identical amount of light.

Efficacy

The efficacy of a light is measured by dividing the light output, or lumens, by the watts used. For example, an incandescent light that uses 100 watts to emit 1,750 lumens has an efficiency of about 17 lumens per watt. CFLs are much more efficient than incandescent lights.

References

• Seattle.gov; Lighting; December 2008
• District of Columbia: Which Compact Fluorescent Light Bulb Is Right For You?