Whether you’re working on a new project or switching to LEDs, identifying the correct shape and size you need makes shopping easier. Each light bulb has a ‘light bulb code,’ which features a letter or letters and a number. Letters in the code indicate the bulb's shape or special features. Numbers indicate the diameter in millimeters or eighths of an inch. The graphic below shows a comparison of the different bulb shapes associated with each letter.
This guide explains the different bulb groups, bulb codes, common applications, and the related light bulb size chart for each group.
Or, use our Universal Bulb Finder to shop by bulb type or screw base.
GLOSSARY:
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A Group: The standard/arbitrary (A) bulb is the most recognizable light bulb shape, with the rounded bulb that narrows into the base.
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B and C Group: All of the bulbs in the B and C groups resemble the shape of a candle flame, often referred to as candle bulbs. This group includes blunt-tip, conical, and conical angular.
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BR Group: Bulged reflector (BR) bulbs provide wide, diffused light output with a gradual fade through frosted, clear, or patterned dome-shaped lenses.
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G Group: Globe (G) bulbs have a full, round shape and are available in various sizes.
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MR Group: Multifaceted reflector (MR) bulbs are small in size and have a reflective, faceted interior.
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PAR Group: PAR stands for parabolic aluminized reflector. LED PAR bulbs are available with narrow beam outputs and wide flood beams.
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T Group: LED tubular (T) bulbs are cylindrical and commonly replace fluorescent light bulbs.
The A Group: A15, A19, A21, and A25
A-group bulbs are typically associated with E26 and E27 bases. The A19 bulb is the most widely used “A” bulb type. These standard bulbs are used in various residential lighting applications, such as:
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Ceiling lights
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Lamps
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Vanity lights
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Kitchen lights
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Closet lights
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Porch light fixtures
The B and C Groups: B10, B11, C7, C9, CA10, C15,
There are three styles of B and C bulbs:
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Conical (C) bulbs are shaped like a cone.
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Conical Angular (CA) bulbs also have a cone shape but have a bent tip.
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Blunt-tip (B) bulbs are very similar to C-type bulbs but have more of a torpedo or bullet shape.
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Blunt-tip Angular (BA) bulbs have the same torpedo shape as the blunt-tip bulbs but have a bent tip.
These bulbs can be used in:
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Chandeliers
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Wall sconces
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Pendant lights
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Night lights
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Decorative light strands
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Holiday light strands
The BR Group: BR30, BR40
BR bulbs produce fewer shadows than PAR bulbs. LED BR bulbs feature an internal reflector that casts light away from the bulb. BR bulbs are slightly longer than PAR bulbs and tend to protrude from light housings, but are used in similar applications, such as
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Track lights
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Recessed lights
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Display lights
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Can lights
The G Group: G14, G16.5, G25, G30
G group bulbs are similar to the A group bulbs, but have a wider shape. The most common type is the large G30 bulb, which is used in bathroom and makeup vanities.
G bulbs can be used for many residential applications, such as:
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Foyer lights
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Kitchen lights
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Chandeliers
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Ornamental fixtures
The MR group: MR11 and MR16
Because of the directional light they provide, MR LED bulbs don’t need facets, but often still have them. These bulbs are available in a variety of colors and can be used for many applications, such as residential, commercial, outdoor, and landscape applications:
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Track lights
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Recessed lights
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Display case lights
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Desk lights
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Driveway lights
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Path lights
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Gazebo lights
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Paver lights
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Landscape spotlights
The PAR Group: PAR16, PAR20, PAR30, PAR36/AR111, PAR38
PAR group bulbs have a shorter body than BR bulbs and are usually installed flush with ceilings or fixtures, which reduces glare. LED PAR bulbs don’t usually have a reflector. Dimmable and weatherproof options are available, making them suitable for:
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Outdoor emergency lights
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Spotlights
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Floodlight fixtures
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Track lights
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Recessed lights
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Display lights
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Can lights
PAR36 bulbs, sometimes called aluminized reflector (AR111) bulbs, have a low-profile, thin shape that is different from the prominent, bulky structure of PAR bulbs. The inside of the bulb is coated in a reflector material or contains faceted reflectors. Reflectors aren’t needed for LED bulbs, but are often still used for a more focused light output without glare.
These bulbs run on low-voltage AC/DC wiring systems and are great for outdoor and landscape lighting applications such as:
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Architectural lights
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Driveway lights
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Path lights
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Gazebo lights
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Paver lights that have weatherproof housings
The T Group: T6, T7, T8, T10, T14, T22
Tubular (T) bulbs come in a variety of lengths and widths. These fixtures are often used in decorative and commercial applications. Depending on their size, T bulbs can be found in:
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Chandeliers
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Wall sconces
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Pendant lights
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Garage troffer light fixtures
Corn Bulbs
Another common style of LED bulbs is the corn bulbs. These high-lumen LED light bulbs emit a powerful, energy-efficient light output. Corn bulbs are commonly used for:
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High bays
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Wall packs
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Post top lights
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Parking lot lights
Smart Bulbs
We carry a wide product selection of smart bulbs. Smart bulbs allow you to switch between RGB and Tunable CCT options with a smartphone or tablet based on your lighting needs. Smart bulbs are available in:
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A19 Bulbs
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BR30 Bulbs
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MR16 Bulbs
This blog explains more about smart light apps and how to use them in your home.
Bulb and Base Compatibility
The bulb shape you use can depend on the fixture’s base type. The graphic below shows relationships between base types and bulb shapes.
*This graphic is based on our specific product offering.
Closing
Selecting the correct LED light bulb for your installation can depend on the fixture, application type, and the desired look. Shop our universal light bulb finder to browse our bulb options, or for additional support in choosing the right bulb, reach out to our customer support advocates and product support specialists at 866-590-3533.
by Super Bright LEDs Experts
The Super Bright LEDs editorial team provides expert guidance on LED lighting solutions for commercial, industrial, vehicle, and residential use. Their trusted insights help businesses and homeowners make informed lighting decisions.
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