A photo of a glowing e12 bulb at left and an e14 bulb at right

Light bulbs come in many shapes, sizes, and wattages. Some of them look very similar – such as the E12 and E14 bulbs – and may seem interchangeable. 

But is that really the case?

This article will discuss E12 and E14 bulb bases and explore their fundamental differences. We’ll also cover the different socket bases available on the market.

Let’s get into it!

Are E12 and E14 Bulbs the Same? 

E12 and E14 bulbs are not the same because they fit different socket bases. E12 is the standard base type for candelabra bulbs, while the E14 is a slightly larger base type for table lamps and other small fixtures. Therefore, bulbs with E12 and E14 bases are not interchangeable and have different dimensions.

What E12 and E14 Mean on a Bulb

E12 and E14 refer to the diameter of the lamp holder, also known as the base, on a light bulb. The E stands for “Edison Screw,” and the number that follows it, 12 or 14, refers to the diameter of the base in millimeters.

What’s an E12 Base?

The E12 base is typically used for smaller, decorative light bulbs such as chandeliers and nightlight bulbs. It has a diameter of 12 millimeters (0.5 inches) and is primarily used in the US, where it is the standard size for candelabra bulbs. However, it is also used in other countries, such as Japan and Mexico.

me holding up an e12 candelabra LED bulb with my bathroom light vanity fixture in the background
Replacing my bathroom vanity lights with these E12 socket base candelabra LED bulbs.

What’s an E14 Base?

On the other hand, the E14 bulb, also known as Small Edison Screw (SAS), has a slightly larger base and is commonly used for household light fixtures such as table lamps and wall sconces. It has a diameter of 14 millimeters (0.6 inches).

The E14 bulb is commonly used in Europe, Asia, and other parts of the world.

Can You Use an E14 Bulb in an E12 Socket or Vice Versa?

You may use an E14 bulb in an E12 socket and vice versa, but you will need an adapter. This adapter acts as a bridge between the two sockets and allows one bulb to fit the other holder. 

The KOR European (E14) to Candelabra Base (E12) Socket Reducer Adapter is the perfect solution for those who want to use a bulb with a candelabra (E12) base in a fixture that has an E14 socket. 

This adapter is designed to reduce the socket size from E14 to E12, allowing for compatibility between different-sized bulbs and sockets.

When choosing among different light bulbs, you must take note of the following:

  • The bulb base corresponds to the diameter of the lamp holder the bulb’s screw goes into. 
  • The screw on the bulb needs to be smaller to fit into the socket base to ensure that the bulb is securely held in place and can be easily screwed in and out as needed.
  • Using a bulb with a screw size that is too large or small for the lamp holder can lead to issues with the bulb not fitting correctly or not making good electrical contact with the socket.

If you are wondering whether the bulb you just bought is energy-efficient, here is our article on four ways to tell if a bulb is energy-efficient.

Which Edison Screw Bulbs Are Interchangeable?

Edison screw bulbs are renowned for their versatility and interchangeability among certain types. As long as the base size is the same, these bulbs can be interchanged with each other to achieve your desired look or amount of light.

E26 and E27

The most commonly used and interchangeable bases are E26 and E27. These bases have a similar thread size and can usually be used interchangeably. However, it’s important to note that the wattage and voltage of the bulb must also be compatible with the fixture.

A incandescent e26 bulb leaning against an LED light bulb on a blue tabletop.

E39 and E40

E39 and E40 are other sets of bases you can use interchangeably. However, it is not a common practice to do so. That’s because the thread outside diameter differs by only one millimeter (0.04 inches), yet the pitch is slightly different. Therefore, it is more likely for an E40 cap to fit into an E39 holder rather than the other way around.

It’s worth noting that E11 and E12 are not interchangeable as they have different thread sizes and different connectors. So while their physical appearance is similar, they have distinct differences.

Other Socket Base Types for a Light Bulb

Not every light bulb uses the same socket base. Various types are available to choose from, including:

Bayonet Base

The bayonet mount is a common fastening mechanism that allows for easy and quick installation of the bulb. The pins on the male side of the connector align with the slots on the female receptor, and then the bulb is twisted to lock it in place. 

This mechanism provides a secure and reliable connection between the bulb and the socket. Different types of bayonet bases can vary in the number of pins and the dimensions of the connector. 


  • B22
  • B15
  • B15d
  • B22d

Bi-Pin Base

A bi-pin lamp base is a light bulb socket that uses two small pins to secure the bulb. The pins are typically located on opposite sides of the base. The bulb is inserted into the socket, with the pins making contact with the electrical contacts inside the socket.

A front and side profile of a pin-based LED bulb

Wedge Base

A wedge base is a light bulb socket that employs a wedge-shaped mechanism to hold the bulb securely. It is akin to a bi-pin connector, using two wires that enter the bulb. However, instead of being stiff, the cables are bent and placed on the sides of the base, where they establish contact with the socket.

The wedge base is commonly used in automotive and other specialized applications.


E12 and E14 bulbs are not the same. The E12 is designed for a lamp holder with a diameter of  12 millimeters (0.5 inches), while the E14 bulb is for a lamp holder with a 14 millimeters (0.6 inches) diameter. The most commonly interchangeable bases are E26 and E27.

Choosing the suitable E12 or E14 bulb and socket base for your specific needs is vital to ensure proper installation and function.


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