A Quick Comparison between A19 Bulb and A21 Bulb
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A Quick Comparison between A19 Bulb and A21 Bulb


Whenever you go over to the light bulb section at the hardware store, you may notice that there are two popular bulbs types - A19 & A21. However, most people do not know their differences, and may falsely assume A19 bulb and A21 bulb are interchangeable. To help out, we made this quick comparison guide here, giving you more details between these two bulbs. Let's take a look at the following contents.






CONTENTS:
What does "A19" or "A21" mean?
Which one is bigger? A19 bulb or A21 bulb?
What bases do they use?
Are A21 bulbs compatible with A19 lamp holders?
Are A19 light bulb and A21 light bulb for different uses?



What does "A19" or "A21" mean?


First of all, it is important to make clear what "A19" or "A21" means. The bulb names of A19 and A21 are actually describing their overall shape through a letter code (A) and their diameters at the widest point in eighths of an inch. The "A" shape bulb was one of the earliest bulb designs and has been a popular bulb type in home lighting. It has a pear shape and Edison screw base. Possessing a standard medium bulb base, A19 & A21 fit in most light fixtures such as table lamps, ceiling fans, wall lights and more. So they can apply for various purposes and occasions in every household. Generally, A21 light bulbs are less known and used in homes compared with their extremely popular counterpart - A19 bulb.



Which one is bigger? A19 bulb or A21 bulb?


When we select or replace a new bulb, we need to know its dimension to make sure it will perfectly fit our lighting fixture. Normally, there is almost no difference in appearance between A21 and A19 bulbs except for their sizes. Let's see it together. A19 bulb is 2.375 inches in diameter(19/8=2.375) and 4.13 inches in height, while an A21 bulb is 2.625 inches(19/8=2.375) and 5 inches in height. So, as you can see, it is clear that A21 has a slightly longer neck and diameter than A19. Users may prefer bigger ones since the size of the light bulb will determine how much heat it can give off, and the more heat it gives off, the higher lumens it provides. In this sense, the A21 bulb works better in heat dissipation and light distribution.



What bases do they use?.


Save for the size difference, their bulb base is also an important element. The bulb base size helps you identify whether they can be screwed into your light fixture sockets to replace the old bulb. Coincidentally, A19 & A21 bulb both have an E26 light base so both can be connected to most standard light fixture sockets.



Are A21 lamps compatible in A19 lamp holders?


Now that they have the same E26 bulb base, you may think that they are interchangeable with each other, but not exactly like this. This is true to a certain level. While the bulb base size helps you identify whether they can be screwed into your light fixture sockets, the dimension determines if the bulb can fit in the lamp head. A19 bulb can be fitted to an A21 lamp holder, but not the other way round. There are two reasons. First, some A19 light fixtures or lamp holders are not designed to accommodate a larger bulb because of the space limitations. Second, A21 bulbs with higher wattage give off more heat that is closer to the lampshade, which increases the danger of fire. So A19 lamp holders may not match well with higher wattage A21 bulbs. Keep this in mind and choose the right bulb according to the size measurement of your lampshade.



Are A19 light bulb and A21 light bulb for different uses?


When it comes to the application, you have to consider several factors including their light distribution, your room size and type, electricity budget, and more. Both A19 and A21 bulb have a 360-degree beam angle, which offers an omnidirectional illumination for any room of varying sizes. Different room types require different brightness levels, so you should figure out the room type to avoid too dim or bright illumination. For instance, kitchens need to be brighter than the bedrooms. A21 bulbs have a higher lumen level and emit stronger lights as 100W incandescent bulbs do. But considering the cost, A21 bulbs also produce higher energy bills. In conclusion, if you don't need a strong and high-cost lighting, A19 led bulb would be an energy-efficient and wallet-friendly option.




Via the comparisons above in dimension, bulb base, and application, now you should understand the differences between A19 and A21. Keep these tips in mind and share with your friends!