Common Bulb Sizes

Did You Know?

By installing CFLs in their most commonly used light fixtures, consumers will do more for the environment and for their own pocketbooks. If more households did this, we could take an important step towards protecting the planet from global warming.

Did You Know?

Bright white and day light CFL bulbs produce a cooler (bluer) light than incandescent lamps. Studies have shown that the human eye can see clearer and with more detail in the bluer light spectrum. Consider whiter CFL bulbs for reading, sewing or any detailed task.

Did You Know?

CFLs are safe to use. The risk of harm from a broken CFL bulb is very small. These bulbs use a lot less energy than regular light bulbs. Using CFLs cuts down significantly on the amount of mercury put into the air from coal-burning power plants.

Did You Know?

CFLs provide the same amount of light (lumens) as standard incandescent bulbs, but have lower wattage ratings.

Did You Know?

As of 2009; Thirty percent of all homes in the US own NO CFLs. Sixty four percent of households that own CFLs have five or fewer.

Did You Know?

Standard incandescent bulbs produce light by heating a filament wire until it glows white hot. Incandescent are about 15% efficient at producing light and 85% efficient at producing heat.

Did You Know?

If every household in the U.S. replaced one light bulb with a CFL, it would prevent enough pollution to equal removing one million cars from the road.

Did You Know?

The amount of mercury in a CFL bulb is very, very small. The mercury in the bulb is in the form of an invisible vapor or a mercury bead. The bead is about the size of the period at the end of this sentence. A mercury fever thermometer has about 100 times more mercury than a CFL bulb.

Did You Know?

Electricity production is the largest source of greenhouse gas emissions in the U.S., and lighting accounts for about 25 percent of American electricity consumption.

Did You Know?

Standard incandescent lamps produce a yellowish light. CFL Bulbs are available in a variety of light colors including warm white (like incandescent), bright white (bluer than incandescent) and full spectrum (like sunlight).

Did You Know?

A CFL (Compact Fluorescent Lamp) bulb is made of glass, a ceramic and metal base, a powder called phosphor, and a small amount of mercury.

Did You Know?

CFLs use one quarter the energy of an incandescent light bulb.

Did You Know?

By using CFLs, the energy saved would actually reduce mercury emissions released from coal-fired power plants.

Did You Know?

CFLs last about eight times as long as incandescent bulbs. They only need to be replaced every five to six years.

Did You Know?

If every household replaced its most commonly used incandescent light bulbs with CFLs, electricity use for lighting could be cut in half. Doing so would lower our annual carbon dioxide emissions by about 125 billion pounds. This action alone could halt the growth in carbon dioxide emissions from the United States, given recent growth rates.

Did You Know?

Replacing one incandescent light bulb with an energy saving CFL bulb would reduce carbon monoxide emissions to the atmosphere by 1,000 pounds.

Did You Know?

Only 11 percent of available light bulb sockets in US homes have a CFL as of 2009.

Common Bulb Sizes

The lighting industry has developed standards for incandescent bulb sizes that have been in use for many years. Table lamp and lighting fixture manufacturers use these sizes to design their products.

In the US incandescent bulb diameters are measured in 1/8 of an inch increments. The lighting industry identifies bulb shapes and sizes by a letter and number code. For example the typical 60 Watt incandescent light bulb would be called an "A19" lamp. The "A" tells us that it has the standard bulb shape that is typical for table lamps. The number "19" tells us that the lamp is 19, 1/8ths of an inch in diameter or 19/8 =2.375 inches.

Some of the more common household shape codes are:

A - Standard "Pear Shaped" light bulb. Typically used in table lamps and enclosed ceiling fixtures.
R - Reflector. Typical used in recessed fixtures.
C - Candelabra or Chandelier. Typically used in chandeliers or ceiling fans. Lamp shapes can vary including flame tip or torpedo.
G - Globe type bulb. Typical use might be in a bathroom vanity fixture.
PAR - Parabolic Aluminized Reflector. Typically used outdoors and has a thicker glass envelope to withstand weather in uncovered fixtures. Can also be used indoors in track lighting. PAR lamps produce a controlled beam of light that can be narrow beam like a spotlight or wider beam to provide aim able general lighting for an area.
MR - Miniature Reflector. Not common in older household fixtures. Typically used as spot lighting for small areas such as over the sink fixtures or a food prep island. MR lamps resemble the reflector in a common flashlight. The recommended energy efficient replacement for incandescent MR lamps are LED. The most common size is MR16.

Common "A" lamp sizes

Name	Inch Diameter
A15	1 7/8"
A19	2 3/8"
A21	2 5/8"

Common Reflector Sizes

Name	Inch Diameter
R14	1 3/4"
R16	2"
R20	2 1/2”
R30	3 3/4"
R40	5"

Common Globe Sizes

Name	Inch Diameter
G10	1 1/4"
G20	2 1/2"
G25	3 1/8"
G30	3 3/4"
G40	5"

Compact fluorescent manufacturers have done an outstanding job in recent years by developing smaller compact fluorescent lamps that closely match the size of incandescent lamps. With the wide variety of CFL shapes and sizes available today you should be able to find an acceptable replacement for virtually any incandescent lamp used in your home.

Some typical compact fluorescent lamp sizes are shown below.


R20 Reflector	R30 Reflector	R40 Reflector

PAR30	PAR38


Typical 14 Watt Torpedo with Medium Base	Typical 14 Watt Torpedo with Candelabra Base


Typical 7-11 Watt A type lamp	Typical 14-15 Watt A type lamp	Typical 16-18 Watt A type lamp