string of standard style/size light bulbs at night in front of trees

June 18, 2025 36 min read

Light Bulb Shapes & Sizes Guide | A19, BR30, PAR38 Explained

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.

A graphic showing what the sha[e of a bulb is based on its 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:

A Group: The standard/arbitrary (A) bulb is the most recognizable light bulb shape, with the rounded bulb that narrows into the base.
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.
BR Group: Bulged reflector (BR) bulbs provide wide, diffused light output with a gradual fade through frosted, clear, or patterned dome-shaped lenses.
G Group: Globe (G) bulbs have a full, round shape and are available in various sizes.
MR Group: Multifaceted reflector (MR) bulbs are small in size and have a reflective, faceted interior.
PAR Group: PAR stands for parabolic aluminized reflector. LED PAR bulbs are available with narrow beam outputs and wide flood beams.
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:

Ceiling lights
Lamps
Vanity lights
Kitchen lights
Closet lights
Porch light fixtures

The B and C Groups: B10, B11, C7, C9, CA10, C15,

Image of a B and C Group Bulbs and the sizes

There are three styles of B and C bulbs:

Conical (C) bulbs are shaped like a cone.
Conical Angular (CA) bulbs also have a cone shape but have a bent tip.
Blunt-tip (B) bulbs are very similar to C-type bulbs but have more of a torpedo or bullet shape.
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:

Chandeliers
Wall sconces
Pendant lights
Night lights
Decorative light strands
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

Track lights
Recessed lights
Display lights
Can lights

The G Group: G14, G16.5, G25, G30

Image of a G shape Bulb and the related sizes

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:

Foyer lights
Kitchen lights
Chandeliers
Ornamental fixtures

The MR group: MR11 and MR16

Image of an MR Group Bulbs and the different size

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:

Track lights
Recessed lights
Display case lights
Desk lights
Driveway lights
Path lights
Gazebo lights
Paver lights
Landscape spotlights

The PAR Group: PAR16, PAR20, PAR30, PAR36/AR111, PAR38

Image of a PAR shaped Bulbs and the various sizes

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:

Outdoor emergency lights
Spotlights
Floodlight fixtures
Track lights
Recessed lights
Display lights
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:

Architectural lights
Driveway lights
Path lights
Gazebo lights
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:

Chandeliers
Wall sconces
Pendant lights
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:

High bays
Wall packs
Post top lights
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:

A19 Bulbs
BR30 Bulbs
MR16 Bulbs

This blog explains more about smart light apps and how to use them in your home.

Showing an LED smart bulb that can be controlled via phone

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.

Image using check marks to illustrate compatibility between light bulb base and shape type

*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.

Why Choose Super Bright LEDs?

When you shop Super Bright LEDs, you can feel confident in knowing you’re getting the highest-quality LED lights on the market. Our in-house test lab rigorously tests all of the products we carry. Additionally, we provide all of our customers with before and after sales support from our call center located at our headquarters in St. Louis, Missouri. And we do all of this while still offering some of the best prices in the industry.

_{*Warranty is subject to change. Please see the product page for a product's warranty.}

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