What is the difference between E26 and E17?

Bulbs are now extensively utilized in a variety of applications, including Christmas lights, outdoor string ornamental lights, night lamps, indication lights, and a variety of other common uses. However, the screw bases vary in size and thread, not the bulb forms, which might be pear-shaped or spherical globe-shaped.

Our tutorial will teach you all you need to know about the typical light bulb socket size for your home’s pendant lights and general lighting. You’ll realize at the end how useful a light bulb socket chart is for deciding bulb holder sizes.

What are the Differences Between Light Bulb Bases

There are lots of different light bulb bases. The most common is the Edison screw base, which may be found on most incandescent bulbs, as well as many halogen, compact fluorescent, HID, and now LED bulbs.

Medium, intermediate, candelabra, and mogul are all frequent words. However, since the lighting business like cryptic codes, you may also see E26, E12, E39, and so on. The letter E stands for Edison. The number after the E represents the diameter of the base in millimeters (mm).

The following are the most often used Edison base names, codes, and applications:

• Chandelier: E12 (12 mm in diameter), also known as the “Miniature Edison Screw MES” base, is used for nightlight bulbs as well as ornamental light bulbs that are used in chandeliers and bathroom mirrors.
• Intermediate: E17 (17 mm in diameter) is in between two sizes. It is often used in desk lights and appliance bulbs, albeit it is not widely available.
• Medium or Standard: E26 (26 mm in diameter) is the size of the majority of light bulbs used in the United States.
• Mogul: E39 (39 mm in diameter) is utilized for street lights and high-wattage lamps.

Most Edison base bulbs are called “single contact” because there is one contact button at the center of the base.

What is the Standard Size of a Light Bulb?

In the United States, the screw medium E26 bulb base has the most common medium base socket measurements of any bulb base. It is present in most incandescent, vintage LED, CFL, and halogen light bulbs. The second most popular bulb base is the Candelabra E12 base, which is used for smaller decorative incandescent/nostalgic lights.

LED bulbs are altering bulb choices; however they still use the same medium base socket size, despite the fact that the bulb performs differently.

It is critical to consider the light output while selecting an LED bulb. It’s measured in lumens (light output), while in the past, everything was measured in watts.

How to Find out the Socket Size and Shape of Your Bulb

This section contains the measurements of a bulb socket, which is useful if you’re attempting to match the socket size of a bulb that already exists.

For a more detailed explanation of light bulb base sizes, you may refer to the letter-number references (E12, E17, and E26) to assist you in determining the style and size of the bulb base.

The first letter identifies the shape or form of the base, while the number defines the width of the base; An E26 base, for example, refers to an Edison screw-in base, with the “E” denoting an Edison screw-in and the “26” denoting a 26 mm base width.

When it comes to light bulb shapes, they are similar to identifying the base size, and light bulbs employ a letter-number reference for the form and size of the light bulb to make this determination. Letters represent form, while numbers represent sizes.

• A (Arbitrary): similar to the normal house bulb.
• C (Conic): also known as a typical Christmas tree bulb, the C (Conic) is the most common.
• G (Globe): a sphere that is circular or round
• S (Sign): straight-sided and is typically used in signs.
• ST (Straight Tapered): mostly seen in antique, Edison-style fixtures.
• T (Tubular): commonly seen in vintage, Edison-style bulbs, tall and narrow.

Edison Light Socket Sizes Chart

Size Name Base major diameter (thread external) Usage Scenario Notes E5 Lilliput Edison Screw (LES) 5 mm Decorative, Indicators Another name is “Midget” E10 Miniature Edison Screw (MES) 10 mm Bicycle Lights, Flashlights Also called “Miniature Screw” E11 Mini-Candelabra Edison Screw (mini-can) 11 mm 20v Halogen Mini Candelabra E12 Candelabra Edison Screw (CES) 12 mm 120v Candelabra, Night Lamp It can be called “Candelabra”, C7 Common US Socket E14 Small Edison Screw (SES) 14 mm 230v Candelabra, Chandelier, Night Lamp, Pendant Light E17 Intermediate Edison Screw (IES) 17 mm 120v Appliances Another name is “Intermediate”, C9 E26 Edison Screw (ES or MES) 26 mm Standard 120v Lights AKA “Medium”, Most Common US Socket E27 Edison Screw (ES) 27 mm AKA “European Intermediate” E29 Admedium Edison Screw (ES) 39 mm Specific Applications such as UV Spotlight Lamps E39 Sing-contact Goliath Edison Screw (GES) 40 mm 120v 250+ W Industrial Known as “Mogul”, Common US Socket E40 Goliath Edison Screw (GES)

As the busy season is kicking off at CLS, we are fielding questions about specifications related to bulbs and cords. This is the beginning of a series answering our most often-heard questions.

The Question: What is the difference between E26, E17, and E12?

Short Answer: There are 3 common threaded sizes of bases of bulbs in the US. The numbers represent the width of the base in millimeters.

Photo showing their relative sizes.

E26 is most commonly seen lighting across large spaces like patios, beer gardens, and amusement parts.

E17 cords (used many times with C9 bulbs) are seen all year but especially at Christmas.

E12 cords (commonly used with C7 bulbs) are seen all year as well but also especially at Christmas.

Many of our customers are learning that Christmas light bulbs and cords can be repurposed for parties and patio lighting by using either their traditional C7 or C9 bulbs or purchasing round bulbs for use during the offseason.

The number after the E is the width of the base of the sockets in millimeters.

Tips for telling them apart

E12: same size as a standard nightlight so grab a nightlight bulb if you don't know if you have an E12 or E17 light string

E17: slightly bigger than an E12 string (so, not the same size as a nightlight!)

E26: the same size as a standard (A19) bulb

Photo of the relative internal sizes of the sockets:

Samples of bulbs with these bases: E26, E17, E12 from left to right.

For more information about bulb shapes, be sure to read more here.