You’ve built the home of your dreams, but now the lights aren’t coming out.
You’re getting ready to take your travel trailer on the road, but now the light bulbs aren’t working.
Whether it’s your permanent home or home on wheels, you need to have the lights on.
Summary
The biggest differences between E26, A19, E27, A21, A15, BR30, ST19, & E12 are the diameters of the base and the light bulb. The difference between A19 and E26 is that E26 refers to the base, and A19 to the shape of the light bulb.
In this article, we’ll also cover the following topics:
- The different bases
- The different shapes
Continue reading
You’ve probably heard that you need a type-A light bulb, but are you sure that it’s a standard base you’re dealing with?
It just so turns out that there are different socket bases, depending on what you’re dealing with. Did you know there’s also such a thing as a type-T?
We’ll teach you everything you need to know about the topic. You’ll learn about standard light bulb bases, and we’ll even provide you with some decorative options to consider.
How does that sound? We’ll get you on the road with the well-lit evenings you deserve, whether for a cozy night or a night of book reading.
Table of Contents
- Standard light bulb base sizes
- E26 bulb
- A19 bulbs
- A19 vs. E26
- E39 sockets
- E12 sockets
- E17
- What is an A21 bulb?
Standard light bulb base sizes
While there’s a range of options to choose from, the E26 light bulb base size is by far the most popular in the US. The second most popular option is the E12 Candelabra bulb base.
In their respective sections, we’ll take a look at each. However, the E12 is usually used for more decorative settings. E26 is by far the more normal option.
The good thing from a compatibility point of view is that you won’t have to concern yourself with whether it’s incandescent or LED. It’s really the socket size that will determine whether you can use it.
Both incandescent and LED E26 will have the medium base socket size you are looking for. It doesn’t matter that the way they work isn’t the same.
Types
Here’s a quick light bulb size chart summary that will hopefully make everything easier to understand. This article explains it thoroughly, so you should now know which socket you’ll need.
| Socket diameter | Market | |
| E12 | 12mm | US |
| E14 | 14mm | EU |
| E26 | 26mm | US |
| E27 | 27mm | EU |
| E39 | 39mm | US |
| E40 | 40mm | EU |
While it may summarize a lot of information, it’s still better to ensure you get the right lighting situation wherever it’s needed. It will help both accomplish the intended need and set the mood!
However, let’s dig a little deeper into the subject. Let’s take a look at some of the specific models to see how they differ. What makes one a better choice than another?
This way, you’ll be able to get the best light solution possible.
E26 bulb
As we’ve mentioned, it’s the most popular option in America. It’s the most regular and standard option there is. This specific type is referred to as having a medium or standards base, and the “E” refers to its shape.
In fact, the “E” stands for Edison screw. The number is a reference to the thickness of the base. The E26 has a base that’s roughly 1 inch in diameter or the equivalent of 26mm.
If a bulb has the same diameter and screw as outlined in this section, it will be referred to as an E26. When you pick up a bulb whose base is roughly an inch in diameter, you’re likely dealing with an E26.
It’s also typically indicated on the packaging despite being the market’s most common model. It’s important that the classification does not refer to the shape of the bulb but rather the base.
A19 bulbs
When you’re going to Home Depot, and you’re looking around the electrical aisle, there are several things you will see.
You will probably see the term “A19” popping up. That’s no surprise. By the end of this section and the next, you’ll know the differences between A19 and E26.
A19 refers to the shape and dimensions of the light bulb rather than its base. It has long been the golden standard used for residential and commercial purposes.
If you’ve ever thought about the classic light bulb shape, this is probably the one you’ve thought of. You will see a striking resemblance when you put it next to an upside-down pear.
So, what’s the number that follows the “A?”
It refers to the diameter of the bulb. It’s measured at the widest point. Here’s the tricky part. It’s measured in eights of an inch rather than millimeters.
How thick do you think it is? It’s usually constructed to be 2.4 inches. It’s the equivalent of taking an eight of an inch 19 times. You get 2.4 inches by dividing 19 by 8.
Countries that use the metric system will have different names for this light bulb. Rather, they will call it an A60. The “60” refers to the diameter the same way that the “19” in “A19” does. The unit of measure is just different.
You will typically find that A19s are about 100-110mm in length. It’s the equivalent of 3.9-4.3 inches.
A19 is a standard that is governed by the ANSI c79.1. Standard dimensions have been determined and will vary depending on the different wattages you’re dealing with.
It’s generally the case that A19 cannot be longer than 112.7 mm in length. At the same time, it cannot have a diameter greater than 69.5mm.
Underneath, you’ll find a chart that easily shows you the maximum measurements for the different wattages of an A19.
| 40W Type 210: | 40W Type 211: | 50W Type 206: | 50W Type 211: | 60W: | 75W: | 100W: | |
| max length | 108 mm | 112.7 mm | 100 mm | 112.7 mm | 112.7 mm | 112.7 mm | 112.7 mm |
| max diameter | 69.0 mm | 69.5 mm | 68.0 mm | 69.5 mm | 69.5 mm | 69.5 mm | 69.5 mm |
A19 vs. E26
A19 vs. E26 bulbs – what’s the deal? If you’ve gotten this far into the article, you may be able to know the difference between the two. The A19 refers to the shape of the light bulb, whereas the E26 refers to the base.
The standards we spoke of earlier have specified some things about the A19, including its base.
Is an E26 the same as A19?
That is the important question. A19 will always use the E26 base. However, an E26 base does not need to have the shape of an A19 light bulb.
Do you understand it? One is always the other, but not necessarily the other way around. E26 is not necessarily the same as A19 because they measure different things.
As the E26 is the most common base used in America, you are generally good if you get a light bulb marked as A19.
You’ll also be happy to know that the A19 standards are the same for both incandescent and LED lamps. LED ones have gained significantly in popularity, but the classification needed to remain the same in the future.
Some advantages of LED lighting include:
- Design flexibility
- Energy efficiency
- Long lifespan
- No heat or UV emissions
- Low voltage operation
It allows for easier retrofitting when you’re changing things out.
E39 sockets
This base is often used on older metal halides and high-pressure sodium. They usually start at 100 wats and go up. As with E26, the letter stands for the screw. It resembles the base of the E26 but with a diameter of 39mm instead.
The diameter of the base allows it to transfer more energy. It means they’re more common in industrial settings. If you think stuff like parking lot lights and warehouse lights, those are places you’ll commonly find them.
They’re also used for wall packs and canopy lights. Whereas the E39 is more popular in industrial settings in America, the norm in Europe is E40. The difference in diameter of 1mm means they can sometimes be used interchangeably.
In the section on E26 vs. E27, we’ll explain why you only may be able to use them interchangeably.
E12 sockets
Having gone through both the E39 and the E26, you may now have an idea as to what the deal is with the E12 base.
Again, the “E” from the E12 refers to Edison. The number refers to the diameter in millimeters.
Since both the E26 and the E39 can transfer more energy with their larger diameters, it’s obvious to see why the E12 can transfer less. It also means that they’re usually used for different purposes.
Pendant lights and various types of decorative purposes are usually where you’ll find these. Their European counterparts are the E14s. Those are also used for the same types of decorative purposes.
E17
E17 has a diameter that lies in between the E12 and the E26. If you find yourself looking for refrigerator or microwave lights, these are relatively common.
Throughout the house, they’re not that common. Your ceiling fan could also be using this type. You may take out the old light bulb and see that it doesn’t seem quite the same size as the E12 or the E26. In those cases, chances are it’s an E17.
What is an A21 bulb?
As with the A19, the term “A21” refers to the shape. Do you remember how the shape of the A19 was determined?
It has a lot of similarities to the A21. The A21 is simply a little bit bigger in its diameter. Rather than having a diameter of 2.4 inches, the A21 has a diameter of 2.6 inches.
The A21 bulb is often used in:
- Table lamps
- Ceiling fans
- Wall lights
- Higher light output applications
It’s the equivalent of 21 divided by 8, as the number indicates the number of eights in diameter. The equivalent of an A19 was A60 in countries that use the metric system. The equivalent of the A21 is A67, which refers to the fact that it has 7 more millimeters of diameter than the A60.
| 100W (v 215) | 100W (v 216) | 150W (v 262) | |
| max length | 112.7 mm | 134.9 mm | 139.7 mm |
| max diameter | 75.5 mm | 78.0 mm | 78.5 mm |
A21 uses the same standard for socket size by using the E26. Once again, an E26 can have the shape of an A21 but can also use a different socket size. An A21 will always use an E26.
