CFL Bulbs Buying Guide

Replace your traditional incandescent bulbs with fluorescent lighting to save energy

Compact fluorescent light bulbs, also known as CFLs, last up to 10 times longer and use up to 75 percent less energy than traditional incandescent bulbs. This guide will walk you through the latest CFL innovations and options.


Incandescent bulbs lose energy in the form of heat. CFL bulbs lose very little energy through heat and thus consume less power.

Tip: Energy savings ratings will vary from manufacturer to manufacturer. Since CFL bulbs do not produce heat, you will also save on cooling costs.

In an incandescent bulb, electric current heats a filament to the point that it glows. In CFLs, electric current energizes argon and mercury vapor, which excites a glowing phosphor coating inside the bulb.

Bulb and Base Design

Like incandescent bulbs, CFLs come in a variety of shapes, suited to different tasks and light fixtures.  

Spiral bulb

Spiral bulb

  • Also known as “twister bulbs”
  • A basic CFL design with visible fluorescent tubes arranged in a spiral
  • Provides even light distribution
  • Ideal for lamps and light fixtures that hide the bulb behind a shade or covering
A-line bulb

A-line bulb

  • Has rounded cover with same basic appearance as standard incandescent bulb
  • Ideal for lamps or light fixtures that don’t conceal bulb
Globe bulb

Globe bulb

  • Sphere-shaped
  • Commonly used in bathroom light vanities and pendant lights
Indoor reflector bulb

Indoor reflector bulb

  • Provides directional light
  • Used in recessed lighting, track lighting, and some ceiling fans
Parabolic aluminized reflector (PAR)

Parabolic aluminized reflector (PAR)

  • Durable; designed for outdoor use
  • Ideal for outdoor flood lights and spot lights
Triple tube bulb

Triple tube bulb

  • Compact bulb with visible fluorescent tubes
  • High light output
  • Takes up little space
  • Ideal for reading lamps
Post bulb

Post bulb

  • Durable
  • Designed for outdoor light fixtures

Bulb Base Type

There are five standard base sizes for CFLs: miniature candelabra, candelabra, intermediate, medium and GU24. Be sure to get a bulb with a base that matches your fixtures.


Miniature candelabra: small bulb base, frequently used in chandeliers


Candelabra: slightly larger bulb base, used in chandeliers, light sconces and other small fixtures


Intermediate: bulb base between the candelabra and medium sizes, commonly used in ceiling fans


Medium: base design for standard light bulbs, used in most lamps and overhead light fixtures


GU24: a two-pin base that fits fixtures with a corresponding GU24 socket. GU24 is an energy-efficient system, designed to replace the conventional, screw-type socket and base design

Light Output & Power Consumption

CFLs are rated based on light output, which is closely related to power consumption. When selecting a bulb, consider its wattage and lumens.  

  • Watts: Bulb manufacturers have traditionally used watts to represent light output, but wattage is actually a measure of power consumption, not brightness. Since CFLs consume less power, a CFL will have a much lower wattage than an incandescent bulb that produces the same amount of light.
  • Lumens: The standard unit of light output for bulbs is the lumen. A higher lumen number indicates a brighter bulb. A CFL and an incandescent bulb with the same lumen rating will produce the same amount of brightness.
  • Equivalent wattage: To make it easier to compare CFLs to incandescent bulbs, manufacturers generally provide an equivalent wattage rating for CFLs along with the lumens rating. The equivalent wattage tells you what type of incandescent bulb has the same light output as the CFL.
  • Lumens per watt: The standard measure of efficiency is the ratio of light output to power usage, represented as lumens per watt, or LPW. A higher LPW rating indicates greater energy efficiency and increased savings.
  • Bulb life: Bulb manufacturers usually provide an estimated bulb life for CFLs, listed in total hours. Quality CFLs have a bulb life rating of 10,000 hours or more. The exact bulb life for a CFL will vary depending on usage.
Light Output Incandescent Bulb CFL Equivalent Estimated Savings of CFL*

250 lumens

25 watts

5 watts

Up to $35

800 lumens

60 watts

13-16 watts

Up to $55

1,600 lumens

100 watts

23-27 watts

Up to $92

2,600 lumens

150 watts

42 watts

Up to $129

* Savings estimates are for lifetime of bulb, based on 3 hours of usage per day, at .12 cents per kilowatt hour


CFL bulbs come in a range of color temperatures, making it easy to replace most incandescents with a CFL alternative.

While the first generation of CFLs had a characteristic blue tint, more recent designs re-create the warm glow of incandescent bulbs.

Bulb color temperature is rated in Kelvins. CFLs on the low end of the Kelvin scale emit a warmer, yellowish light, like a conventional incandescent bulb.

CFLs with higher Kelvin numbers emit a bluer light, like conventional fluorescent lights.

To maintain consistent light quality, use bulbs with the same color temperature in a room.  

Type Kelvin Range Description

Soft White

  • 2,500 - 3,000k
  • Warm, yellowish glow
  • Ideal for living rooms, dens and bedrooms

Bright White

  • 3,500 - 4,100k
  • Crisp, white light
  • Ideal for work areas and kitchens


  • 5,000 - 6,500 kelvin
  • Similar to natural sunlight
  • Ideal for reading and detail-oriented work

Safety and Recycling

CFLs typically contain 4 mg of mercury. As long as the bulb is intact, the mercury is safely contained. Avoid contact with a broken bulb.

If you break a CFL, air out the room for 15 minutes. Approach the cleanup carefully, following the Environmental Protection Agency’s recommended procedure.

The EPA recommends that you bring old CFLs to qualified recyclers, rather than disposing of them in trash cans or curbside recycling bins.

You can bring old CFLs to The Home Depot for free recycling. Visit the Eco Options website to learn more.

If you’re concerned about the mercury content in CFLs, consider LED bulbs. Since LEDs don’t contain mercury, they don’t have the same cleanup constraints, but are just as energy-efficient.