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A19 vs A21 Bulb: A Best Comparison Review 2022

Nowadays, without light, there would be no life, which is not only important but the reality of human life. Blessings of electric lamps gave people complete control over lighting inside their homes and workplaces at the click of a switch. As the days go by, people used to become choosy to look for qualitative light bulbs with understanding common household light bulb shapes, sizes and styles is important.

There are so many categories of light bulbs but at night time everyone needs natural light through electricity. We would like to compare the two light bulbs that are usually supposed to be interchangeable. In this article, we will be evaluating A19 and A21 lamps and we will try to find out the difference between these two light bulbs.

Top 05 A19 LED Bulbs

1A19 LED Vintage LED Filament Bulb E26 Base,LVWIT Dimmable 7W (60W Equivalent),2700K Warm White 800 Lumens,Omnidirectional, UL-Listed, Pack of 6
2SYLVANIA ECO LED A19 Light Bulb, 60W Equivalent, Efficient 9W, 7 Year, 750 Lumens, Non-Dimmable, Frosted, 5000K Daylight – 24 Pack (40987)
312V LED Light Bulb 7W 630Lm AC/DC 12-24Volt Low Voltage E26 Base (2700K Warm White)40-60 Watt A19 Bulbs Equivalent- Landscape Garden Yard, 12volt Battery Power System Off Grid Solar Lighting- 6 Pack
4Philips LED Frosted A19, Non-Dimmable, 800 Lumen, Soft White Light (2700K), 10W=60W, E26 Base, 16-Pack
5Haian 12V LED Bulb 7W 700Lm E26/E27 Standard Base 60W Equivalent 12 Volt Low Voltage Lights AC/DC 12-24V A19 Lamp,Cool White 6500K,Off Grid Solar Battery System Lighting,RV,Marine LED Lights,6 Pack

A19 & A21 Bulb Comparison

While you consider choosing a light bulb at the hardware store, you will find many types and categories of light bulbs. There are probably two types almost alike but different in size as A19 or A21 bulbs. This is to determine exactly what is the difference between these two sizes and how does the size affect them differently. Probably you may not know that size plays a vital role in bulb and socket compatibility. To make it clear, we will be talking about the difference between these two models of bulbs as well as some of the features with applications used by both of them.


Obviously, there is a vital reason for naming the two types of light bulbs. Bulbs that feature the letter code “A” represent the shape, while the two-digit numbers indicate its widest point or size. Logically, the A19 and A21 household bulbs are built for a multitude of purposes. Even the size is different, as the A21 bulb is larger than the A19 bulb, though it looks alike and comes with a nominal power of 40 and 60 Watts. Both the bulbs produce between 450 and 800 lumens. It’s usual that homeowners would like to have brighter lights and may opt for incandescent bulbs that have a nominal power of about 100 Watts.

Now the practical difference in between the two are stated below:

Dimension – A19 Bulb

As the numbers indicate, its size or dimension which we mentioned above, and as such the A19 light bulb has a diameter of 2.4 inches (e.g. 19 divided by 8 inches), and the length of the A19 bulb is 3.9 – 4.3 inches. Converting in millimeters, the A19 light bulb has a dimension of 112.7 mm in length and 69.5 mm in diameter.

Dimension – A21 Bulb

On the other hand, the A21 light bulb has larger dimensions of 2.6225 inches and a length starting from 4.1 to 5.4 inches. Measuring in millimeters, it is 78.5 mm in diameter and 139.7 mm in length. In comparison with measurement, the A21 light bulb is longer than the A19 light bulb.

Judgement: A21 Bulb is the Winner

In considering the dimension of the two light bulbs, the A21 light is bigger in size than the A19 light bulb. While size may be the main and most obvious difference between the two bulbs, they also have differences in power. Bulbs’ power is usually measured in lumens and lumen refers to the illuminating power a bulb emits when you turn it on. An A21 bulb apparently produces higher lumens as compared to an A19 bulb size because the A21 bulb has a bigger space for heat dissipation.

For your better understanding regarding the size of these two light bulbs, check the video down below.


The base is one of the important factors, as for the reason, from the base size you will come to know what light fixtures that can be fitted. You must be well known with base size if you have a bulb in your light fixture. Both light bulbs are ordinary bulbs, therefore, it needs to determine whether they are the same in base size or any difference in between.

Base – A19 light bulb

The base is referring to the size structure and most A19 lights come with inch long screw base. Actually, it is the medium size of all bases and considered the standard base size in the US. As per standards, the dimensions and design of A19 light bulbs dictate that it must use an E26 screw base. In particular, all A19 light bulbs also have an E26 base. But all bulbs are not like the E26 base of the A19 form factor.

Base – A21 light bulb

Not at all surprising, but in reality, the A21 light bulb is the same as the E26 light base. There is no difference, but similar to the A19 light bulbs. Actually E26 light bulbs base are more or less universal and have the standard base measurement for most of the sockets in every home. In accordance with ANSI standards, A21 bulbs must always use an E26 base for mounting into a light fixture. Be careful that not all E26 bulbs will be of A21 shape.

Judgement: Equal – Both the bulbs are winning here

Both the two light bulbs have the same base sizes, therefore, either of the two can be connected to the standard light fixtures at home. Whatever you need to fix a light bulb bigger or smaller, no matter what, you can easily consider choosing either of the two bulbs and the result will be the same. In a remark, both light bulbs are equal in this race.

Distribution Degree:

One of the most important factors is the degree of distribution of light from the bulb, as it is essential to know the room type while you consider fixing the light. The room’s size and shape of different buildings all over are usually not the same. There are many types of room areas. Someone might be bigger like a hall room, some is medium and small. So according to room measurement, specific light bulbs should need to be fixed and the degree of distribution will also allow you to provide a final choice. For this reason, you need to consider how far the light covers and what angle can give light enough for consuming the room.

Distribution – A19 light bulb

The A19 light bulb does not come with reflectors, because they don’t have built-in reflectors, which make it capable of emitting light in a full 360-degree angle. As a result of which you can confidently articulate, this bulb can light up a medium-size room evenly.

Distribution – A21 light bulb

On the other hand, the A21 light bulb also features a 360 degrees angle to enhance the distribution of light. Therefore, placing the A21 light bulb in a bulb socket or a bulb holder, you can ensure or secure an even delivery of light all throughout the whole room very easily.

Judgement: Equal – Both the bulbs are winning in this case

In comparison with the two bulbs, that impartially can be said that either of the two bulbs can provide a reasonable degree of angle to distribute the light in a room. So whatever light bulb you choose, you can ensure the best satisfaction of light distribution. Marking with competition, both are equal in this race.

Pros and Cons

This is almost clear and you might be already articulating the advantages and disadvantages of both the light bulbs if you read this article with proper concentration. The aforesaid two light bulbs are often preferred to use. As because both A19 and A21 light bulbs are able to meet the standard bulb Base and also the Distribution, though the Dimension is a little different. As discussed before, the size is not an issue as either of the two can provide you with the best lighting. The A19 is smaller in diameter than A21 and this is only the thing that differs from their sizes. Therefore, no matter what, you can easily get whatever you prefer.

Detail below is a quick summary of the Pros and cons of both products:

Pros – A19 Light Bulbs 

  1. This Light bulb can able to provide light instantly
  2. Environmentally friendly
  3. Available in different color temperatures
  4. It can last for 15,000 hours of use
  5. Not associated with infrared or ultraviolet radiation

Cons – A19 Light Bulbs

  1. The color quality may be poor
  2. Where smart technology is included, the setup might be quite difficult

Pros – A21 Light Bulbs

  1. Lights up quickly
  2. Dimmable
  3. Less complicated to make
  4. Bright enough for different purposes

Cons – A21 Light Bulbs

  1. It’s not such durable
  2. It might not light consistently

Frequently Ask Question

 1. Is A21 a standard Bulb?

The Bulb letter code is ‘A’ stands for the classic group and the most common type of household and residential light bulbs, including other office buildings with a pear shape and Edison screw base. A standard A21 is little bit larger than A19 light bulbs, as the name of the bulbs like A19 and A21 is actually describing the shape as well as the diameter of a bulb.

2. Is A19 a standard Bulb?

An ‘A’ type of bulb has the classic light bulb with shape and size, commonly compared to an upside-down pear. Two digits after the letter refer to the bulb’s diameter at its widest diameter and its widest point is measured in eighths of an inch, which is approximately 2.4 inches. Therefore, A19 Led light bulbs are standard light bulbs as the shape is so ubiquitous that this is likely the first form factor. The outputs range from A19 bulbs come 20 Watts up to 100 Watts in their incandescent forms.

3.Are A19 and A21 light bulbs interchangeable?

If we answer this question in a word that is “YES,” for the reason A19 light bulbs are smaller in all dimensions than A21 light bulbs, virtually they will fit in all fixtures and light holders designed for A21 bulbs. While they utilize the same E26 base, the A19 lamps will fit into the socket just fine, and obviously, A19 and A21 light bulbs are interchangeable.

Bottom Line:

Choosing a light bulb is the liberty of householders, who like to fix the light bulbs of their home, office, and other necessary premises. But sometimes, as a buyer, you may not really see the significance of differentiating A19 and A21 bulbs. Therefore, it is essential to concentrate on the topic of this Article, where we elaborated and made the best efforts covering maximum information about A19 vs A21 light bulbs. We also summarized the Pros and cons of both the products, which might be helpful for you to purchase the best one.

Even further, to update on the features and application, as stated in the review comparing both the bulbs, we can confidently stick on our judgment. You may already know, the A21 bulb would be a better purchase between the two. As it boasts a larger diameter, making it capable of containing the right amount of energy/heat from the electricity. Hence, our verdict towards A21, notwithstanding as per our final remark, both have the same base as well as the degrees of the light distribution. So any of the two will grant you enough light, but A21 light bulbs advantages are considerably better.

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