B11 vs. E12: Chandelier Light Bulb Shape and Base Types


Besides checking a bulb’s brightness and color temperature, you must get a fitting bulb size for your lighting fixture’s socket. Also, there is the bulb shape, a variable that should match the fixture’s design or help enhance aesthetics. Bulb manufacturers usually indicate these two variables as codes, which can be confusing to beginners. Take a look! We will demystify the most typical shape and base codes, B11 vs. E12, in the article below.

E12 vs. B11: Codes Explained

B11 describes the light bulb shape, in this case, a bulb with a flame or torpedo-shaped glass body. The letter B refers to the bulb’s glass body shape, while the number indicates its diameter.

GE flame-shaped bulbs

GE flame-shaped bulbs

On the other hand, E12 describes the bulb’s base type. E refers to the Edison type, while the number shows the base diameter. The E12 base is also known as the candelabra base.

A bulb with an E12 socket

Therefore, you can get a bulb with both B11 and E12 or either in the description of its features.

Chandelier Light Bulb Shapes

Since there is a B11 shape, it makes sense to assume there are other shapes, and they exist. But remember, the number (11 in this case) refers to the body’s diameter. Therefore, there are different letters to denote the shape, and they include the following.

  • A: Arbitrary/ Classic pear shape 
  • B: As described earlier, this letter refers to flame, torpedo, bullet, or ammo
  • C: Cone or candle
  • CA: Candle angular or candle corner
  • F: Flame style
  • G: Globe, spherical, or round style bulb
Different chandelier light bulb shapes

Different chandelier light bulb shapes

Chandelier Light Bulb Base Types

The size code for a candelabra bulb is E12, and E refers to the Edison style. This style is threaded and screws into a threaded socket in the fixture. Most US households use this base style, but the diameter can vary.

For instance, the candelabra light bulb with base E12 has a 12mm diameter. The other typical base type is E26, a medium base bulb with a broader 26mm diameter base.

An E26 vs. E14 base light bulb. The E12 base is 2mm slimmer than the E14.

An E26 vs. E14 base light bulb. The E12 base is 2mm slimmer than the E14.

Most wall sconces, lamps, and decorative lighting fixtures have either base types to maximize compatibility.

B11 vs. E12: Diameter Specification

The number section of the light bulb shape code shows the diameter of the widest part of the glass body. Similarly, the base code number indicates the widest diameter at the bulb base. It is vital to note that the bulb glass diameter is given in inches while the base code gives the diameter in millimeters.

Bulb Diameter (B11)

We always consider the widest diameters because that is the only section that matters when fitting bulbs in lighting fixtures.

For instance, with the glass body size, some fixtures have narrow spaces that cannot accommodate the globular incandescent bulb. Therefore, you can only fit slim bullet bulbs.

In some cases, you should consider the bulb diameter for aesthetic purposes. For instance, chandelier lighting fixtures look better with candlelight bulbs due to their shape and traditional usage. String lights also look better with candle-shaped bulbs. Therefore, the code helps pick the best size for the job.

A candle-shaped bulb

A candle-shaped bulb

With that in mind, manufacturers indicate the shape size standard in eighths of an inch. Therefore, B11 is 11/8 (11*1/8) inches wide or 1-3/8 inches and is about 3.88 inches long. Here is a diameter and length comparison between different bulb shapes to give a better understanding.

ShapeDiameter (inches)Length approximate (inches)
B1010/8 or 1-1/43.75-3.9
F1010/8 or 1-1/43.06
CA1010/8 or 1-1/44-4.25
C1515/8 or 1-7/84.5
C99/8 or 1-1/82.75-3

While the diameter is easy to determine, the length varies depending on the bulb manufacturer.

Bulb Base (E12)

As for the base, the most typical ones are the 12mm candelabra base and the 26mm medium base. The purpose of the base diameter code is purely to assist with fitting, not for aesthetics like with the glass body.

An E12 ball-shaped bulb

An E12 ball-shaped bulb

If you want a B11 bulb with an E12 base and can’t get that 12mm fixture size, there is a workaround in the form of base adapters. These screw into the fixture using one diameter and provide a port with a different diameter. However, adapters can be expensive, especially if you have several multi-socket candelabra lighting fixtures.

What is Equivalent to an E12 Bulb?

The lighting fixture socket size is the primary determining factor of the bulb type to purchase. You can opt to use an adapter as described earlier, but this is an expensive option. There is no other equivalent or alternative to an E12 lamp base, so you should get bulbs with this base diameter if your fixture has 12mm sockets. These include the following.

  • T6, T8, and T22 tiny bulb tubes
  • G14, G16, and G50 small bulbs
  • B10, C7, C9, and CA10 light bulbs
A decorative C9 light bulb

A decorative C9 light bulb

Where to Use B11 E12 Bulbs?

B11 E12 style bulbs are ideal for decorative fixtures, such as wall sconces, chandeliers, lampstands, night lights, bedside table lamps, and pendant lights.

Pendant bulb lighting

Pendant bulb lighting

Christmas/string lights for festivities also use these decorative bulbs. These applications explain why the E12 is also known as the candelabra base. But do not associate this name with the candle-shaped light bulb because it is the base name, not the body shape name.

String lights

String lights

Can You Use Other Shapes On E12 Base?

Most people associate the B11 chandelier bulb shape with the E12 base to the extent that they call the candelabra-style bulb B11.

However, you can get other bulb shapes that sit on the E12 base, ranging from the A types of chandelier bulbs to the G type. Most A bulb types are ideal for general kitchen downlights, while G bulb types are perfect for decorative lighting applications in vanities and around mirrors.


These bulb shape and size codes can be confusing, and here are some answers to clarify some typical questions.

Are B12 and E12 Bulbs The Same?

B12 is a glass body shape code, while E12 is a base size code. B12 implies the bulb’s maximum glass body diameter is 12*1/8 (1.5 inches), while E12 means the bulb’s base diameter is 12 millimeters. Therefore, the bulb can be the same if these dimensions match.

Are B10 and B11 Bulbs Interchangeable?

B10 and B11 are bulb glass body codes. A B10 bulb is 10/8 inches wide (1.25 or 1-1/4 inches), while a B11 bulb is 11/8 inches wide (1-3/8 inches). If the bulb bases are the same (either E12 or E26), you can interchange the bulb, provided the chandelier fixture has enough space to accommodate the wider body.

Different bulb shapes and base sizes

Different bulb shapes and base sizes

Are B10 and E12 Bulbs Interchangeable?

B10 and E12 bulbs are not interchangeable because they refer to different things. B10 implies the bulb has a maximum glass body diameter of 10/8 inches or 1.25 inches. Thin torpedo tip bulb shapes usually come in this size.

On the other hand, E12 means an Edison light bulb base measuring 12 millimeters wide.

Are E11 and E12 Bulbs Interchangeable?

E11 and E12 bulbs are not interchangeable. E11 bulbs (mini-candelabra) have an 11mm diameter base, while E12 bulbs (candelabra) have a 12mm broad base. The former is typical in halogen bulbs and the latter in decorative lights.


In conclusion, most people assume that B11 and E12 are two of the most basic bulbs, but these refer to body shape and base size codes. Therefore, you don’t have to choose between the two when shopping for a chandelier light bulb. We hope this article has clarified the two terms and will help you pick the correct light bulb. If you have any questions, drop a message in the contacts section, and we’ll get back to you asap.

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