CFL stands for Compact Fluorescent Lamp


A compact fluorescent lamp, or CFL, can have a socket base (also known as an Edison base) or a pin base. Most have standard socket bases.

CFLs are rated first by “color temperature,” listed in degrees Kelvin (“K”). The lower the Kelvin temperature rating, the more yellow the lamp, while the higher the Kelvin temperature rating, the whiter the light becomes. The color of the setting sun is rated about 3000 K, while the bright midday sunshine would be 5000 to 6000 K. 

CFLs come in a range of color temperatures:

SOFT WHITE is commonly referred to as warm yellowish light, which closely approximates the lights used in household reading lamps. The color temperature is rated at around 2500 to 3200 degrees Kelvin. 

BRIGHT WHITE is usually referred to as a crisp white light often chosen for work areas and some office environments. This color has a temperature of about 3700 to 4100 Degrees Kelvin.

DAYLIGHT is the color of light in a bright outdoor atmosphere. This is similar to direct sunlight and has a color range of about 5000 to 6000 Degrees Kelvin.

Another way CFLs are rated on lumens per watt, as with other types of lamps. This is a measurement of light output. CFLs have a high lumens-per-watt index ratio. A 13 watt CFL puts out about 800 lumens of light.

CFLs versus Incandescents

Incandescent bulbs have a very poor lumens-to-watts ratio — so poor that an incandescent lamp is 90 percent heat and 10 percent light. By comparison, a 60-watt incandescent bulb puts out about 800 lumens, which is the same amount of light generated by a 13-watt CFL.

Even if you do not have great math skills, it is easy to see that if both lamps produce about 800 lumens, a CFL uses 13 watts of electricity, and the incandescent uses 60 watts of electricity, the CFL, is more than four times as efficient as the incandescent

Here is a handy comparison of CFLs and incandescent lamps:

  • A 23-watt CFL produces about 1600 lumens, the same light as you would get from a 100-watt incandescent bulb.
  • An 18-watt CFL produces about 1100 lumens, the same light as you would get from a 75-watt incandescent bulb.
  • A 13-watt CFL produces about 800 lumens, the same light as you would get from a 60-watt incandescent bulb.
  • A 9-watt CFL produces about 450 lumens, the same light as you would get from a 40-watt incandescent bulb.

So, the ratio pretty much holds up: the CFL is more than four times as efficient as the Incandescent — and it lasts more than four times as long.

CFLs Yield Improved Performance

CFLs have come a long way in 10 years of production:

  • They no longer require a warm-up period.
  • They do not flicker, but instantly light up fully on demand at room temperature.
  • They last from 8,000 to 10,000 hours — again, at least four times as long as any incandescent. To put that into perspective, 10,000 hours is equal to more than three years of use, if the lamp were burned seven days a week, eight hours a day, year after year.


These are the reasons we use the CFL lamp in our Ceiling Fixture retrofit kits. CFLs are cost-efficient to purchase at about $2 to $3 each. They last a long time, and they cost very little to operate.

In addition, CFLs offer the user choices: The user can increase or decrease illumination with a simple twist of a lamp or change color on demand by simply switching out the lamps.