The Differences Between A19 Bulb vs E26 Base

Some consumers are puzzled about the differences between A19 bulb and E26 Base. A19 refers to a bulb's shape and size, while E26 refers to the base of the bulb that screws into a light fixture.

To help you make the right choice for your lighting fixtures, this article breaks down the definitions of each term and how they relate to one another.

The Fundamentals: A19 vs. E26

The core difference between A19 and E26 is what part of the bulb they describe.

• A19: This code refers to the shape and size of the bulb's glass enclosure.

• E26: This code refers to the size and type of the base, which is the part that screws into the light socket.

In short, A19 describes the glass "head" of the bulb, while E26 describes the metal "tail."

What is an A19 Bulb?

"A19" is the industry standard code for the most common household light bulb shape.

• "A" stands for "Arbitrary": This denotes the classic, pear-like shape that has been used since the early days of incandescent lighting.

• "19" indicates the diameter: The number represents the bulb's widest point, measured in eighths of an inch. Therefore, an A19 bulb has a diameter of 19/8 inches, or approximately 2.375 inches (around 60 mm).

An A19 bulb is designed to cast light downwards in an omnidirectional pattern, making it ideal for general-purpose lighting in lamps, ceiling fixtures, and wall sconces.

What is an E26 Base?

"E26" refers to the metal base of the bulb that connects to the electrical socket.

• "E" stands for "Edison": This pays homage to Thomas Edison, who invented the screw-in base mechanism.

• "26" indicates the diameter: The number refers to the thread diameter in millimeters. An E26 base is 26 mm wide.

The E26 is the standard "Medium Edison Screw" (MES) base used in North America and parts of Asia. It is the most common base type in the US, found in everything from floor lamps to recessed can lights.

How They Work Together

This is the most important takeaway: A19 and E26 are not interchangeable terms, but they are often paired together.

• The vast majority of standard A19 bulbs sold in North America come with an E26 base. If you pick up a classic-shaped light bulb at the store, it is almost certainly an A19 bulb with an E26 base.

• However, an E26 base can be found on bulbs with different shapes. For example, a globe-shaped "G25" bulb or a reflector-style "BR30" floodlight can also have an E26 base.

In summary: A19 is the shape. E26 is the connector. Knowing this distinction ensures you buy a bulb that not only fits into your socket but also has the right shape and look for your fixture.