An E12 light bulb on its side with the text "e12 ???" superimposed above it

If you’re in the US, you have probably encountered the E12 candelabra bulbs. While they are not as prevalent as regular E26 socket bulbs, you’ll still find them on appliances requiring small bulbs. 

But if you’re buying bulbs for the first time, identifying E12 light bulbs could be daunting. However, you shouldn’t worry if that’s the case for you, as this is why we are here. 

We plan to leave no stone unturned in identifying the critical features of E12 light bulbs and elaborating on their uses. Also, you’re in the right place if you have common FAQs on these types of bulbs. 

What is an E12 Light Bulb?

An E12 light bulb’s screw base measures 12 millimeters in diameter (or just under a half inch. Also noteworthy, they are a type of Edison screw light bulb, hence the letter E in their name. You can tell if a bulb is an E12 most will have an E12 inscription on the surface or box.

Otherwise, you can check if it’s small-sized & has a screw base measuring 12mm in diameter. E12 represents the bulb’s base, with the E identifying it as an Edison screw (ES) type, while ’12’ is the bulb’s diameter in millimeters, as mentioned. So it’s that simple to tell an E12 light bulb. 

But what are some of its applications and similar bulbs? Let’s find out.

E12 Lamp Base Dimensions

The IEC standards 7004-28-2 provide the specific lamp base dimensions for E12 light bulbs that manufacturers should comply with. We’ve summarized the measurements in the table below. 

Lamp Base PartDimension
Thread Length (Inclusive of the Bulb Solder)Minimum: 11.7mm
Thread Length (Without Bulb Solder)Minimum: 10.66mm
Solder AreaMinimum: 1.66mm
Total DiameterMinimum: 15.24mm, Maximum-17.01mm
Total Diameter (Solder Contact Area)Minimum: 3.58mm, Maximum: 4.37mm

Common Screw-in Sockets (US)

The primary identifier of E12 light bulbs is that they feature Edison screw lamp bases. This base has threads that perfectly lock into the socket, akin to driving a typical screw into a nut. 

Notably, the E type of bulb is named after Physicist Thomas Edison, the brainchild of such bulb design. Hence, if you are using line-voltage lamps with a screw base, it will probably be an E12 or the other three main types.

They include: 

E12 or Candelabra Base

This base is the style for most screw-type small bulbs in the US. Ideally, you’ll find it in bathroom mirrors, Christmas trees, and decorative light bulbs. 

me holding up an e12 candelabra LED bulb with my bathroom light vanity fixture in the background

E17 or Intermediate Base

As its name suggests, this is an intermediate type of base (between E12 and E26). Its screw base diameter measures 17mm, as per its name, and you’ll primarily find it in appliance bulbs. Nonetheless, it is not as common as the E26 base. 

E26 or Standard Base

Most light bulbs in the US will have this base—no wonder it’s called the ‘Standard’ or Medium Base. True to its name, the diameter of the base is 26mm, suited to fit in a similarly sized socket. 

Up-close of a light bulb base against a dark background

E39 or Mogul Base

This fitting is the most common screw base for high-wattage lamps such as street lights. With a screw base diameter of 39mm, they are uncommon for household use as they are best suited for outdoor lighting applications. 

We’ve covered just the standard bulbs screw bases in the US, so these are not the only ones you’ll find. So without veering off from our primary base type (the E12), let’s see where to use it. 

a mercury vapor fixture hanging in a warehouse
Mogul (E39) bases are for much bigger bulbs that are meant to put out a ton of light, and are usually about 12-15ft up in the air at least. When I owned my previous energy efficient lighting company, we would do a ton of mogul-based bulb LED retrofit projects for gyms, warehouses, parking lots, retail stores, and other large areas.

Where Can I Use E12 Bulbs?

Primarily, E12 bulbs feature a relatively small screw base which translates to one thing that is highly revered in decorative lights–a small and compact form factor. Thanks to their small size, they’ll perfectly fit in decorative fixtures such as the lights you see in a chandelier. 

Another key feature is their relatively low wattage rating (most are rated 40W and below). So this tells you that they are not as bright as your average lighting bulbs, but they have a luminous intensity good enough for decorative and accent lighting. 

Given the qualities we’ve just highlighted, you’re likely to find E12 light bulbs in the following applications: 

Essential Features of E12 Bulbs

When dealing with E12 light bulbs (primarily for decorative lighting), there are two things you should focus on including: 

  • Color Rendering Index (CRI)
  • Color Temperature

Why are the two important? Well, essentially, E12 bulbs are helpful in decorative applications. So, unlike the general lighting bulbs, E12 bulbs have to yield a light of exceptional quality to best fit their designated application. 

Let’s see in detail why each of the features is crucial. 

Color Rendering Index (CRI)

Your E12 light bulb should have a relatively high CRI, especially if you’re using it as accent lighting (focusing the light on a particular object). Ideally, a CRI of about 90 and above is perfect. 

Basically, the higher the CRI (1 to 100 scale), the more it emits light close to the sun’s natural color. So to have the highest lighting quality (90+ CRI in the real world), you want it to appear as if it’s under natural lighting.

Hence, a high CRI means you can achieve this effortlessly. Otherwise, your objects will appear dull, which beats the logic of having specialized E12 LED lights. 

Color Temperature

Think of a candlelight kind of color temperature. You should obtain that from your E12 light bulbs, as it’s fundamentally a decorative and classic feel kind of bulb.

Color temperature is also known as Kelvin Temperature. It’s basically what color output the bulb has. You can see the charts below for what I mean. It’s important to know what kind of color you want a space lit with, or it can feel just not quite right.

We have a whole article on why Kelvin Temperature is important here, if you want to check that out.

LED bulbs linked up with all different kelvin temperature colors.

A temperature of 1900K won’t light up enough to provide the suitable bright illumination of candlelight. But, again, don’t go to a high color temperature of about 2700K, as that is exceptionally bright, especially if you want to mimic genuine candlelight. 

Hence, the best temperature should be something around 2400K–this won’t be too warm to conceal the intricate details of the surroundings and yet not too bright to remove the candlelight experience. 

a modern looking graphic diagram of orange colors to white and bluish on the range, indicating different Kelvin color temperatures in lighting

Common E12 Bulbs FAQs

Let’s ponder a few of the most oft-asked questions pertaining to E12 light bulbs:

Is E12 Standard Base?

In the US, the standard base is the E26 and not the E12, which is not as prevalent as the former. 

What is an E12 Fitting?

An E12 fitting is an Edison screw base type with a diameter of 12mm. It is also known as the Candelabra base, and in terms of size, it’s less than half of the standard E26 base. 

What is the Difference Between C7 and E12?

C7 represents the shape and size of the bulb, primarily in the glass part.

On the other hand, E12 represents the diameter of the bulb’s brass metal base in millimeters. Thus, a C7 bulb can have an E16 base or a larger one, such as E17. 

How Do I Determine the Bulb Base Type?

You can identify a bulb’s base type outright by checking its letter-number inscription for reference. For instance, a bulb with an E12 inscription has an Edison screw measuring 12mm in diameter. 

an LED candelabra bulb sitting on a table with a black background

Final Thoughts

Now you have it all on E12 light bulb base types. In a nutshell, any bulb with the conventional style of Edison screw that can perfectly fit in a 12mm wide socket is an  E12 light bulb. Today, most of these bulbs are LEDs, but you can still find incandescent, CFLs, and halogen bulbs with such a base. 

Our rule of thumb is that you should always go for LEDs, as they are the ultimate energy savers. Also, they are the way to go if you’re looking to lower your soaring electricity bills. 

Thanks for reading and check out our site for more tips on saving energy.  

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