Are B11 And E12 Bulbs Interchangeable?

How many home projects have you seen on YouTube and thought to yourself: well, that’s easy enough! And you get cracking on it, ready with your measurements, your written plan, and all the equipment you need to shop for.

But sometimes you hit a glitch that has you scratching your head in bewilderment as to what has gone wrong.

One such scenario is the common mixup and confusion when choosing candle-shaped bulbs. It is usually assumed that E12 and B11 are two basic-types of the bulb, and one has to choose between the two options.

However, while in the market, you can find one bulb that has both E12 and B11 in its description. How come?

The codes E12 and B11 refer to two different specifications. E12 is the type of the bulb’s base, while B11 refers to the bulb type, and describes its shape. Both of these are usually found in the same bulb, leading to the mixup.

E12 And B11 Codes Explained

There is widespread confusion when choosing the candle-shaped bulb for chandeliers, string lights, signage, or marquees. You need a very specific base for the bulbs to fit in your socket.

When people need to buy these bulbs, the code E12 and B11 cause the doubt about which of the two codes applies to their specific requirement.

The reality is that both of these codes refer to entirely different things and are not mutually exclusive.

E12 is the description of the base type of the bulb and is the candelabra Edison screw base.

B11 is the description of the bulb type and the candle shape of the glass body.

The confusion usually arises because these two codes and descriptions are usually found in the SAME bulb, where one refers to the base and the other refers to the bulb.

Diameter Specification

As if buying the right bulb was not puzzling enough, that there needed to be multiple codes looking similar but referring to different specifications.

Have faith, because these codes are there to help you pick the EXACT bulb that would fit your needs. I will help explain the difference.

Going into detail, the E12 on the bulb code means an ‘Edison’ screw-in type with a base that measures 12 millimeters across the widest part of the base (not bulb).

On the other hand, B11 means the bulb’s glass body ends in a ‘Blunt’ tip at the top, usually shaped like a candle, bullet or torpedo!

In standard American units, the measurement is given in eighths of an inch. So the number 11 means the diameter but it becomes 11/8 so 1.375 inch.

When I convert it to mm its about 35 mm in the widest part of the glass body.

On the other hand an E12 is as we know 12 mm in diameter, but unlike the shape, the base is not converted to eighths so it just stays as 12 mm.

The E12 helps you decide which bulb base will fit into the light socket that your fixture has, and after that, the B11 will help you pick out the desired shape of your bulb.

Determining the required shape of the bulb if also quite important. Sometimes a light fixture cannot allow a bigger bulb or a globular bulb to fit in, so only the slim bullet shape will serve the purpose.

In other cases, it is all about aesthetics. Traditional chandeliers and string lights look distinctively beautiful owing to the candle shape of the bulbs that have been used for years.

So first comes the base, and then you can pick out the shape. If you don’t find the exact bulb with this combination, you can do one of two things.

First, if you have found the B11 shape, but not the E12 base, you can purchase adapters to change the base from an E12 to an E26. But this can be an expensive option if you need to buy adapters for every socket.

Secondly, you can stick to the E12 base, but opt for a CA11 bulb type similar to the B11, and is also shaped like a candle but is quite pointy at the end, like a flame.

Other options can include a G50 bulb type, which is spherical and like a globe.

Both B11 and CA11 are 35 mm at their widest part of the body, so they can be easily interchanged.

In case you have not yet purchased the light fixture that your new bulbs will go into, you can use an E26 base with the traditional B11 bulb type, provided that the new fixture will be compatible with the E26 base.

Where Are B11 E12 Bulbs Used?

E12 B11 bulbs are most commonly used in decorative lighting and festive settings, such as chandeliers, wall sconces, pendant lights, night lights, string lights, and numerous other applications.

That is why the E12 bulb base type is commonly referred to as candelabra. This is another confusing aspect as one thinks of the candle-like BULB SHAPE when imagining a candle shape. In this case, candelabra is the name of the BASE.

And that is exactly why this guide needed to be written!

Can You Use Other Shapes On E12 Base?

So at the end of the day, the bulb you need to purchase is restricted by the socket that you already have in your light fixture.

Let’s suppose your fixture has a threaded socket that will take a screw-in bulb, then you need to look for the E12 base type, as nothing else will fit in the socket!

Once you have sorted all E12 base bulbs and can see a few different options for the BODY of the bulb, you can then choose the bulb type.

The bulb type can be labeled A for Arbitrary, the classic, pear-shaped light bulb shape used for general lighting in kitchen downlights.

Or the bulb type can be labeled G, which signifies the globe and is a very spherical, round-shaped bulb used for decorative purposes and brilliant lighting in vanities and bathrooms around mirrors.

Finally, you can find the B bulb type, which is most likely what you would have been looking for if you are in the market for the E12 base.

So the B11 bulb type is explicitly most often associated with the E12 base, to such an extent that a candelabra bulb is also commonly referred to only as a ‘B11’.

Final Words

This has been an enlightening guide to write and hopefully, for you to read as well.

Do you have light fixtures or decorative lamps and chandeliers that need the E12 B11 bulbs to look beautiful?

Leave a Comment