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A19 vs A21 Light Bulb [Differeces, Similarities, Pros and Cons]

A19 vs A21 Light Bulb

When Thomas Edison first successfully invented the light bulb, we are sure he never imagined that there would be so many options for us to choose from. Despite it being an apparently simple task, I’m sure we aren’t alone in having a draw full of random light bulbs that don’t meet our purpose.

To understand the difference between the A19 vsA21, we first need to understand a little more about how light bulbs work.

How Do light bulbs work?

Inside a light bulb, you will find a filament that is a thin tungsten wire which electricity flows through. As the filament heats up it starts to glow and therefore converts electrical energy into light energy. The power that a light bulb uses is measured in Watts. The amount of light that is emitted from a light bulb is measured in Lumens.

In the past, we were more concerned about Watts because the older circuits could only cope with a certain amount of power drawn. This was when we only had the option of the traditional incandescent light bulb. Now, thanks to LED (light-emitting diode) light bulbs, our buying options have become more about the lumens and the ability to efficiently light up a room.

We are going to compare the A19 light bulb and the A21 light bulb. We will take a closer look at their power consumption, lumens, and ideal uses. Once we have looked at their value for money and some pros and cons of each, we will decide which of the two is the better option.

Because there are so many different variations of the two lightbulbs, we are going to look at a summary of their features and include a comparison chart of the A19 and the A21 based on one specific brand.

A19 vs A21 Light Bulb

The Base of the A19 and the A21

Both of these lightbulbs have a standard-sized screw-in base, the E26 base. They can be used interchangeably and will fit in most of your usual fittings from table lamps to ceiling lights.

The Size

All light bulbs with an A on them refer to a certain size or method of measuring them. This type of light bulb is the pear-shaped light bulb. It is the diameter of the light bulb at its widest point divided by 8. The A19 has an average height of 4.13 inches. Its diameter is 2.375 inches. The A21 has an average height of 5 inches. The diameter is 2.625 inches

A21 Led Bulb

Watts and Lumen

The A19 and the A21 normally come in the equivalent of 40W, 60W, and 100W, which will emit 450 lumens, 800 lumens, and 1600 lumens respectively.

Color Temperature

The A19 and A21 LED light bulbs to have a different range of colors from warm to cold. The Color Temperature is measured in CCT. A CCT rating of around 2,700K will produce a warmer color, whereas 4,000K is a much brighter, crisper light.

The Life Span

Again, if we look at the A19 and the A21 LED light bulbs, you will be able to appreciate between 20,000 and 30,000 hours of life from one battery.

A19 bulb


Most of the A19 and the A21 light bulbs are made of metal and glass. The brand we looked at uses thermoplastic, glass and aluminum.

Value for Money

Naturally, because the A19 and the A21 Led light bulbs last for so much longer, they will cost more than the traditional light bulbs. Between the A19 and the A21, the A21 light bulb is slightly more expensive but you are only looking at a few dollars extra for a multipack.

Ideal Uses

Apart from the difference in size, the ideal uses are where the A19 and the A21 tend to differ. Because of the larger surface area of the A21, it is better suited to larger rooms and ceiling lamp fittings. The A19 is the better choice for table and floor lamps.

A21 Led Bulb Base

Comparison Chart

For the sake of a fair comparison, we have chosen to compare one LED A19 and one LED A21 light bulb from the same brand.

  A19 LED Light Bulb A21 LED Light Bulb
Height 4.13 inches 5 inches
Diameter 2.375 inches 2.625 inches
Base Type Standard screw-in base Standard screw-in base
Lumen 1,000 1,600
CCT 2,700K 2,700K
Watts 11W (equivalent of 100W incandescent bulb) 14W (equivalent of 100W incandescent bulb)
Ideal Uses Table and floor lamps, small rooms Larger rooms
Life Span 25,000 hours 25,000 hours
Materials Thermoplastic, glass, and aluminum Thermoplastic, glass, and aluminum

Pros and Cons

We have put together some pros and cons of the A19 and the A21 light bulb but not based on any specific brand.

A19 Light Bulb

A19 led bulb


  • An A19 LED light bulb will cost around $1.20 a year based on average use of 3 hours a day
  • The warm lighting is very cozy
  • Some brands offer up to a 10-year warranty


  • It would be nice to see a different range of shapes and designs for lamps

A21 Light Bulb

A21 bulb


  • The LED A21 uses 90% less energy than traditional A21s with more potential savings
  • The additional limen makes the room look not only brighter but somehow more modern
  • They are better value for the money


  • All A19 light bulbs can be used in all E26 features, the A21 may not fit in all fixtures because it is larger

The Final Verdict

As there is nothing overly exciting about either of the designs, the decision can’t be based on looks. It isn’t really a question of which one is the better buy. The first thing to consider is the use. If you have a smaller table and floor lamps that are awkward to change the light bulb, you will want to use the A19 light bulbs because they are smaller and will fit more easily. The A21 may also be too bright for lamps. On the other hand, the A21 light bulb provides an excellent amount of light for ceiling fixtures.

Whether the A19 or the A21 is the most suitable option for you, we do strongly recommend choosing the LED light bulbs over the incandescent light bulbs. The savings are far greater over the long run.