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Home » A19 vs A21 Light Bulbs: What are the Differences? ( 2023 )

A19 vs A21 Light Bulbs: What are the Differences? ( 2023 )

A19 vs A21 Light Bulbs

The decision to switch from incandescent light bulbs to LED bulbs was an easy one. The next step is to unravel the huge variety of numbers and letters to find the right light bulb for your home or office. Two in particular that you would think are almost identical are the A19 and the A21.In this article we try to compare A19 Vs A21 light bulbs with latest information we have till January 2023 .

The first part to understanding light bulbs is the letters and numbers. The letter refers to the shape and the number the size. ‘A’ light bulbs are the traditional pear-shaped light bulbs. The larger the number, the bigger the diameter of the bulb.

In the comparison chart below, you can see the exact differences between the A19 vs A21.

A19 vs A21 – Side by Side Comparison




ImageA19 Light BulbA21 Light Bulb
Height3.9-4.73 inches4.1-5.4 inches
Width2.4 inches2.6 inches
Average BrightnessUp to 1,600lmUp to 1600lm
Average Watts9.5W15W
Incandescent Equivalent60W100W

Because of the size difference, the main thing you need to consider is the type of light fixture you have. The smaller 2.4-inch A19 will fit in practically any light fitting. The A21 has a 2.6-inch diameter and is better suited to lamp holders. The length might make a difference, depending on how much you want the bulb to protrude or not.

The A19 and A21 have an E26, screw-in base, which means in terms of their connection, they are interchangeable.

The power consumption is a more considerable difference. The A21 uses an average of 15W (100W incandescent equivalent), whereas the A19 uses just 9.5W, or a 60W equivalent. This will vary from brand to brand and so will the average brightness. Both the A19 and the A21 have up to 1600 lumens. If you are looking for dimmable LED light bulbs, this might not be so relevant.

A19 vs A21 in CFL or LED types

Both A19 and A21 light bulbs you can purchase in Compact fluorescent lamp ( CFL ) or a lite-emitting diode (LED ) format.

CFL and LED replaces incandescent lamps. As A19 was more popular in incandescent lamps most of the CFL and LED bulbs can be found in A19 format. Since year 2020 companies have started producing more CFL and LED bulb in A21 format as well.

Shape for A19 and A21 light bulbs

Both A19 and A21 light bulbs uses Arbitrary shape . Which is quite similar to bulged shape but more wider on the top. That helps light to spread more evenly in all direction.

A19, A21 light bulb shape compared with other light bulbs

Different Types of A19 and A21 Light bulbs

There are several types of light bulbs available for an A19 light bulb socket, including incandescent, halogen, compact fluorescent (CFL), and light emitting diode (LED).

Incandescent light bulbs are the most traditional type of light bulb. They work by heating a filament inside the bulb until it becomes hot enough to emit light. They are generally inexpensive, but they are also the least energy-efficient type of light bulb and have the shortest lifespan.

Halogen light bulbs are similar to incandescent bulbs in that they also use a filament to produce light, but they are more energy-efficient and have a longer lifespan. They contain a small amount of halogen gas, which helps to extend the life of the filament and make the bulb more efficient.

Compact fluorescent (CFL) light bulbs are a type of energy-efficient light bulb that use a small amount of mercury and a gas-filled tube to produce light. They are more energy-efficient and have a longer lifespan than incandescent bulbs, but they can take a little longer to reach their full brightness.

Light emitting diode (LED) light bulbs are the most energy-efficient type of light bulb. They work by using a semiconductor to convert electricity into light and are extremely long-lasting, with some models rated to last up to 50,000 hours. They are also very efficient, using up to 90% less energy than incandescent bulbs to produce the same amount of light.

A19 vs A21 : based on capabilities


The Only advantage we see in A21 over A19 is it’s ability to get over the heat issue for higher usage. When size of the Light bulb is higher manufacture has added advantage to go higher power  , Increase surface area in Any electronics can easily distribute the heat, This was if we compare A21 vs A19.  A21 turns out to be winner here for this part.

If you plan to use a lots of light bulbs in concentrated area Where temperature is quite high A21 is a better choice Compare to A19 light bulb

—Research Data
~Source Global Electrical commission

A19 vs A21 : Which is more energy efficient ?

One of the main differences between A19 and A21 bulbs is their energy efficiency. A19 bulbs are typically more energy efficient than A21 bulbs, which means they use less electricity to produce the same amount of light. This can save you money on your energy bills and also reduce your carbon footprint.

A19 Vs A21 : which light bulbs last longer?

Another difference between these two types of bulbs is their lifespan. A19 bulbs generally have a longer lifespan than A21 bulbs, which means they’ll need to be replaced less frequently. This can save you time and money in the long run.


When to use A19 Light bulb and A21 light bulbs ?

When to use A19 Light bulb?

A19 light bulbs are typically used in household and commercial lighting fixtures that have a medium base (E26). They are a versatile and widely used light bulb that can be used in a variety of settings, including:

  • Table lamps
  • Floor lamps
  • Pendant lights
  • Ceiling fans
  • Wall sconces
  • Chandeliers
  • Recessed lighting

Usage of A19 Light bulb compared with A21, Mostly used for small confident spaces

A19 light bulbs are available in a range of wattages, so you can choose the right amount of light for your space. They are also available in different types, such as incandescent, halogen, compact fluorescent (CFL), and light emitting diode (LED), so you can choose the most energy-efficient option for your needs.

When to use A21 Light bulb?

An A21 light bulb is a standard household light bulb with a medium base (E26) that is slightly larger than an A19 light bulb, with a diameter of approximately 2.625 inches. It is often used in lighting fixtures that require a higher level of light output, such as in large rooms or outdoor spaces. A21 light bulbs are available in a range of wattages, so you can choose the right amount of light for your space. They are also available in different types, such as incandescent, halogen, compact fluorescent (CFL), and light emitting diode (LED), so you can choose the most energy-efficient option for your needs. Some specific examples of when you might use an A21 light bulb include:

  • Large living rooms
  • Dining rooms
  • Kitchens
  • Outdoor porch lights
  • Landscape lighting
  • Streetlights

Usage of A21 Light bulb compared with A19, Mostly used for big , open areas and outdoor spaces

Like A19 light bulbs, A21 light bulbs are widely used in many countries around the world.

A19 vs A21 : Which is more Popular ?


We went through difference customer reviews across United states and compared Brightness , Energy Efficiency , Value for money and Longevity for A19 and A21 light bulbs. here is the Result of this comparison.

A19 Compared with A21 on Customer Satisfaction out of 5 Points:



Energy Efficiency4/53.7/5
Value For money4.5/53.5/5
Overall Review4.2/53.9/5
Based on Consumer of these light bulbs clearly A19 is the winner.


A19 and A21 on the Market Today

To get a clearer picture of the similarities and differences between these LED bulbs, we have taken a look at the Philips A19 and the Philips A21. These model of the lightbulbs serves as a reference and guide for your selection of Either A19 or A21 light bulbs. It helps to know incase you buy how it will be look like. A19 vs A21 follows the similar fundamental design . If you like to know more about other types of light bulb do check out our light bulb comparison section .

The Philips A19

Height, weight and Length of A19 light bulb

For the best savings, you can choose from the 4 pack or 6 pack. They are 2.5 inches in diameter and 4.7 in height. They use 8.8W (like a 60W incandescent bulb) and have 800lm. They give off a warm glow with 2,200-2,700K, so good for relaxing areas. These are frosted, dimmable bulbs that don’t flicker. You can expect an average lifespan of 15,000 hours.

The Philips A21

Hight, weight and Length of A21 light bulb. A19 vs A21

Philips has chosen to make this bulb larger than average at 3.07 inches in diameter and 5.51 inches in height. However, it is still frosted, dimmable, flicker-free, and available in packs. It’s a 12W light bulb, equivalent to 75W, and has 1,100lm and 2,700K. Again, it offers a warm glow in rooms, but Philips has specified the lamp holder use.

Read next – A15 vs A19 Light Bulbs: What is the Differences?

The Final Verdict on A19 Vs A21 : What to select ?

The A21 will be the right choice for many but we prefer the A19. The size makes this light bulb more suitable for different uses. Using less energy means your electric bill can be kept lower, plus they are generally cheaper.