A19 vs A21 Light Bulbs: Choosing the Right Size for Your Needs

When it comes to choosing light bulbs for your home or office, the A19 vs A21 are two of the most common options. While they may seem similar at first glance, there are some key differences between these two bulb types that you should consider before making a purchase.

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What Are A19 and A21 Light Bulbs?

The A19 and A21 light bulbs are both part of the A-series, which refers to their pear-shaped design. The numbers indicate the diameter of the bulb at its widest point, measured in eighths of an inch. An A19 bulb has a diameter of 2.375 inches (19/8 inches), while an A21 bulb measures 2.625 inches (21/8 inches).Despite their size difference, both A19 and A21 bulbs typically use the standard E26 base, which fits most light fixtures. However, it’s important to note that some A21 bulbs may have a larger E27 base instead.

Advantages of the A19 Bulb

The A19 has been the standard bulb size for over a century, so most light fixtures are designed to accommodate its height and width. This means that an A19 bulb will fit in a wide range of fixtures without any issues.Additionally, the A19 is generally more economical than the A21. It produces less light output, generates less heat, and uses less electricity. If you’re looking for a cost-effective option that still provides adequate lighting, the A19 may be the better choice.

Advantages of the A21 Bulb

While the A19 is the more common and compatible option, the A21 has some advantages of its own. Since it’s larger, the A21 can produce more light output than an A19 with the same wattage. This makes it a good choice for larger spaces or if you want to maximize the brightness in a room.The A21 is also a good option if you need a bulb that can withstand higher temperatures, such as in a ceiling fan or enclosed fixture. Its larger size allows for better heat dissipation, which can extend the bulb’s lifespan.

Choosing Between A19 and A21

When deciding between an A19 and A21 light bulb, consider the following factors:

  • Size of your light fixture: If your fixture has a small enclosure or lamp shade, an A19 may be the better choice to avoid compatibility issues.
  • Desired light output: If you need maximum brightness, an A21 may be preferable. If you just need adequate lighting, an A19 may be sufficient.
  • Energy efficiency: The A19 is generally more energy-efficient, so it may be the better choice if you’re looking to save on electricity costs.

Ultimately, both A19 and A21 bulbs are versatile options that can be used in most standard light fixtures. The choice between the two will depend on your specific needs and preferences.


In conclusion, when choosing between A19 and A21 light bulbs, it’s important to consider the size of your light fixture, desired light output, and energy efficiency. While the A19 is the more common and economical option, the A21 offers advantages in terms of brightness and heat dissipation.

If you have a small light fixture or are looking for a cost-effective solution, the A19 is likely the better choice. However, if you need maximum brightness or are using the bulb in a high-temperature environment, the A21 may be the way to go.

Ultimately, both A19 and A21 bulbs are reliable and widely available options that can meet the lighting needs of most homes and offices. By considering the factors mentioned above, you can make an informed decision and choose the bulb that best suits your specific requirements.

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