A19 vs A21: What are the Differences? - Comparison Guide
A19 vs A21

A19 vs A21: What are the Differences?

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Light bulbs are a fundamental part of any home or office, and selecting the right type of bulb can make a significant difference in the lighting quality and ambience of a space. With so many options available on the market, it can be overwhelming to decide which type of bulb is the best fit for your needs. Two popular types of bulbs, the A19 and A21, are commonly used in many households and workplaces. Understanding the differences between these bulbs can help you make an informed decision about which one is right for you. In this article, we will dive into the details of A19 and A21 bulbs and compare their key features such as size, brightness, energy efficiency, color temperature, and pricing. By the end of this article, you should have a better understanding of the differences between these two types of bulbs and be able to make an informed decision about which one is best for your needs.

Differences Between A19 and A21

Shape and Size

    • A19 Bulb: The “A” in A19 stands for “arbitrary,” indicating the bulb’s general pear-like shape. It has a diameter of approximately 2.375 inches (60mm) and a length of around 4.13 inches (105mm).
    • A21 Bulb: The A21 bulb is larger than the A19 bulb. It has a diameter of approximately 2.625 inches (67mm) and a length of around 5.31 inches (135mm).

Light Output

      • A19 Bulb: A19 bulbs typically have a lower wattage and provide a lower light output compared to A21 bulbs. They are commonly used for general lighting purposes in residential and commercial applications.
      • A21 Bulb: A21 bulbs can accommodate higher wattages and provide a higher light output than A19 bulbs. They are often used when brighter light is required, such as in larger rooms or spaces.


    • A19 Bulb: A19 bulbs are commonly used in various fixtures, including table lamps, floor lamps, pendant lights, wall sconces, and ceiling fixtures.
    • A21 Bulb: A21 bulbs are typically used in larger fixtures, such as floor lamps, pendant lights, and ceiling fixtures, where higher light output is desired.

It’s worth noting that both A19 and A21 bulbs are available in different types, such as incandescent, compact fluorescent (CFL), and LED, each offering different energy efficiency, lifespan, and light quality characteristics.


Both A19 and A21 bulbs have their pros and cons, and the choice ultimately comes down to your personal lighting needs. If you’re looking for a standard, energy-efficient bulb for everyday use, A19 bulbs are a great option. However, if you need brighter lighting for larger rooms or spaces, A21 bulbs may be a better choice. It’s always a good idea to compare different types of bulbs and read their specifications to make an informed decision.


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