Difference Between A19 and A21 LED Light Bulbs

Difference Between A19 and A21 LED Light Bulbs


LED bulbs have many options when it comes to shape and size. You might be confused about which one will perfectly fit your place in the wide range of light bulbs. Every light bulb is different from the other, whether it comes to shapes, sizes, features, performances, etcetera. Talking about the difference between the two types of LED light bulbs, A19 and A21, simply refers to the size and shape of the bulb. As the name suggests, A19 and A21 light bulbs sound quite similar, but the most significant difference is size. The A19 bulb has a diameter of 2.375 inches, while the A21 bulb measures 2.625 inches.

You will understand the difference between them after reading the detailed meaning of both LED light bulbs.

What do A19 and A21 LED Light Bulb Mean?

Light bulbs have different codes related to shape, size, base type, etc., that are mentioned below with explanation. The letter or number code you see on the packaging of the bulb describes its shape and size. Commonly, A and C are some kinds of letters known in light bulbs.

  • The bulb with code A is a naturally rounded pear shape in which A stands for arbitrary. However, this is not the complete form of describing the shape and size as the A letter comes with a number code that defines the diameter of the bulb.
  • On the other hand, the letter C stands for the candle-shaped light bulb, which starts wider before making a conical point. The C-type also comes with a number to define the exact size of the bulb in diameter.

Now, the A19 and A21 are the metric forms to determine the shape and size of the LED light bulb. The major difference makes both the light bulbs diverse from one another. Along with this, most of the time, both A19 and A21 come with the same base type, E26.

Are A19 and A21 LED Light Bulbs interchangeable?

When it comes to changing an A19 LED light bulb to an A21 LED light bulb, they can be interchangeable because these codes don’t refer to the base type. The changing process will not successfully completed if the base type of both bulbs is different. As we mentioned above that both A19 and A21 LED light bulbs have the same E26 base type, but sometimes the B22 base type also appears in a very rare condition. In common situations, both bulbs can be swapped because their base connection is identical, and the diameter of both bulbs is not too wide for each other.

Here, the base type of light bulb refers to the connection to the lighting fixture. There are also codes for different base types in which E, B, or G-type are included and commonly used in the US.

  • The E-type bulbs are Edison bulbs that come with a screw fixture to make a connection with the lighting fixture.
  • The B-type bulbs are bayonets, and they refer to the bulbs that come with two pins that are inserted and twisted in the lighting fixture.
  • Finally, the G-type bulbs are spotlights that come with pins that move into place to connect to the lighting fixture.

All the base types come with letters and numbers to determine the detail of the light bulb. Now, the number in the base type refers to the diameter of the base, or it can be the distance between the pins in millimeters.


As we clarified that the only difference between A19 and A21 LED light bulbs are the shape and size. But, you can also see another difference in base type in both bulbs because they can come with a B22 bayonet base type as well or with a larger base type of E27. So, the fact that A19 and A21 LED light bulbs are interchangeable is not always true as it depends on the base type of the bulb. Otherwise, the size and diameter of the bulbs vary, which is by far the only difference between them.

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