CFL Sizes and Shapes

The ENERGY STAR CFL search can help you find a specific bulb to meet your needs or see if a particular model is qualified.

For specialty bulbs not common in stores, find model numbers through the search tool, and then use your favorite search engine to find the model online.


  • Only bulbs marked "dimmable" will work on dimmer switches.
  • Only bulbs marked "three-way" will work on three-way sockets.
  • Most photocells and electric timers don’t work with CFLs, so check with the manufacturer of the control for compatibility.

Shapes and Sizes

image of Spiral CFLs


If these spiral-shaped bulbs look familiar it’s because they’re the most popular type of CFL. Spiral CFLs create the same amount of light as traditional incandescent bulbs, but use less energy.

image of an A-shaped CFL


A-shaped bulbs combine the efficiency of the spiral bulbs, with the look and feel of the traditional incandescents. These products are great for consumers who don’t like the look of the spiral bulbs but still want efficient lighting. You can use A-shaped bulbs wherever you used to use traditional incandescent bulbs, such as clip-on lamp shades. Check the packaging for compatibility with dimmers and three-way fixtures.

image of a Globe CFL


Globe-shaped bulbs are ideal for bathroom vanity bars and ceiling pendants. Like other covered CFLs, globes need a little time to "warm up" and reach full brightness. But be patient — ENERGY STAR qualified light bulbs generate just as much light as traditional bulbs, while using less energy.

image of a Tube CFL


Some of the first ENERGY STAR qualified light bulbs were tube shaped. Basically straight versions of the spiral bulbs, tubed bulbs work well in lamps that have slender covers such as wall sconces.

image of two Candle CFLs


These products are ideal for use in decorative fixtures where you can see the light bulb. The sleek shape also allows you to use them in tight fitting light fixtures where a covered globe won’t fit.

Post CFL image


Covered post bulbs are great for outdoor fixtures; manufacturers design these bulbs to hold up to outdoor conditions. There are also yellow "bug light" covered posts, designed to keep away insects. Check compatibility with timers and photocells.

image of Indoor Reflector CFLs

Indoor Reflectors

Reflector bulbs are perfect for providing directional light — think of recessed ceiling lights in kitchens or ceiling fans. Indoor reflector bulbs are much smaller than those that are designed for outdoor use. Some are small enough to fit in ceiling fan lights, and some can be used with a dimmer — the packaging will tell you.

image of Outdoor Reflector CFLs

Outdoor Reflectors

For use outside, reflector bulbs are sealed to withstand the rain and snow. Because of this, they’re usually much larger than the reflectors designed for use inside. Don’t use the outdoor reflectors with timers, photocells, and motion sensors because you could shorten the life of the bulbs.