Do you need new screw base light bulbs but are unsure what you need for your fixture? Distinguishing between the different types of base styles can get overwhelming. This light bulb fitting guide goes in-depth into the various kinds of screw bases and what application each best fits.
Why Does the Base Type Matter for Light Bulbs?
Each light fixture has a socket requiring a specific base type. Installing an incompatible bulb can cause malfunctions or fires. Also, different bases are better suited for particular applications and design choices. Smaller bases are standard in decorative applications, and larger bases are used in industrial and commercial lighting.
How Do You Distinguish Between Light Bulb Base Sizes?
Each base type also has a descriptive term that denotes the size: candelabra, medium or standard, intermediate, and mogul. After you know the screw base type you need, decide what shape and size of the bulb you want. Understand the different light bulb shapes and sizes here.
What Does “E” Mean in Bulb Bases?
If a base type starts with an "E," that indicates it's an Edison screw base named after the inventor, Thomas Edison. There are several types of screw bases, including E12, E14, E17, E26, E27, and E39. The number refers to the base diameter at the crest of threads in millimeters.
Common Screw Base Types
E26/E27 Medium – Edison 26-mm or 27-mm Diameter
Bulbs with E26/E27 bases are the most popular screw-base bulbs. The locations where they’re used differ between E26 vs E27 because E26 base bulbs are primarily used in North America, while E27 bulbs are often found in Europe, Asia, Australia, and South America. E26 and E27 base bulbs are used for general lighting in standard fixtures, such as lamps, outdoor spotlight and flood light fixtures, and vanity lights.
Common bulbs with E26/E27 bases:
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A-shaped bulbs: A19, A15, A21
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Globe-shaped bulbs: G30, G25, G16.5
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PAR bulbs: PAR16, PAR20, PAR30, PAR38
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BR bulbs: BR20, BR30, BR40
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Blunt-tipped bulbs: BA11
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Marquee and sign bulbs: S11, S14
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ST bulbs: ST18, ST19, ST21
E12 Candelabra – Edison 12-mm Diameter
E12 base bulbs, also known as Miniature Edison Screws (MES), have a 12mm diameter screw base. Many bulbs with these bases mimic the look of a candle flame. Bulbs with E12 bases are often used for decorative lighting applications, such as restaurant pendant lights, ornamental lights, residential or commercial string lights, and night lights.
Common bulbs with E12 bases:
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Small tube-shaped bulbs: T8, T6, T22
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Candle-flame-shaped bulbs: C7, C9, CA10, B10
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Small globe-shaped bulbs: G14, G16, G50
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Blunt-tipped bulbs: B10, B11, BA11
E14 European – Edison 14-mm Diameter
E14 base bulbs, also known as Small Edison Screws (SES), are popular in Europe and other markets for small light fixtures and spaces requiring a compact bulb. Popular applications for E14 screw base bulbs include chandeliers, wall sconces, lamps, Christmas lights, restaurant pendant lights, ornamental lights, residential or commercial string lights, sign and marquee lights, night lights, and bathroom vanities.
Popular bulbs with E14 bases:
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A-shaped bulbs: A15
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Small tube-shaped bulbs: T8, T6, T22
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Candle-flame-shaped bulbs: C7, C9, B10
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Small globe-shaped bulbs: G14, G16, G50
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Marquee and sign bulbs: S11
E17 Intermediate – Edison 17-mm Diameter
E17 base bulbs are usually found in Asia and North America and are used in appliance lighting, such as microwaves, refrigerators, range hoods, traditional ceiling fan light fixtures, and desk lamps. They are also used for decorative applications, such as chandeliers, wall sconces, Christmas lights, pendant lights, ornamental lights, and sign or marquee lights.
Common bulbs with E17 bases:
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A-shaped bulbs: A15
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Small tube-shaped bulbs: T8, T6.5, T22
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Candle-flame-shaped bulbs: C7, C9
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Small globe-shaped bulbs: G14, G16, G50
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Marquee and sign bulbs: S11
E39/E40 Mogul – Edison 39-mm or 40-mm Diameter
E39/EX39 bases are primarily used in North America, while E40 bases are popular in Europe and other markets. EX39 base bulbs can operate in E39 and EX39 lamp holders since EX39s have a longer tip. However, you can’t use E39 base bulbs in EX39 lamp holders. These powerful, energy-efficient bulbs have high light output and replace HID bulbs in industrial fixtures, such as high-bay warehouse lights, parking lot lights, canopy lights, and wall packs. LED E39/EX39 base bulbs are typically cylindrical, similar to ED and BT HID bulbs. LED corn bulbs are another popular type of E39/EX39 screw base bulb, which resembles a corn cob. E39 and E40 base bulbs can be used interchangeably. However, their sockets are rated for different voltages. Ensure you’re using the correct bulb/socket combination to avoid safety hazards.
Popular bulbs with E39/E40 bases:
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PAR bulbs: PAR38
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Blown tubular bulbs: BT37, BT56
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Elliptical dome bulbs: ED17, ED28, ED37
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Frequently Asked Questions
How Do I Know What Base My Light Bulb Has?
If you’re installing bulbs in a new fixture, check the inside diameter of the lamp holder while the fixture is disconnected from power. If you’re replacing an existing bulb, the existing one should have a code printed on it indicating the base type.
What is the Difference Between E12 and E26?
The main difference between E26 and E12 bulb bases is the size. E12 bases have 12mm diameters, and E26 bases have 26mm diameters. They also differ in their types of applications. While E12s are used for decorative lighting, such as chandeliers or Christmas lights, E26 bases are used in standard home lighting applications like ceiling fans and can lights.
Can I Use an E27 Bulb in an E26 Socket?
Yes, as long as the bulb is rated for the socket’s voltage, E27 bulbs can typically be used in an E26 socket. However, since E26 bulbs receive only 120V compared to E27s, which receive up to 240V, installing an E26 base in an E27 socket increases electrical risks.
What Screw Base Types Are Regularly Used in the U.S.?
E12, E26, E39, and EX39 are the screw bases often used in the United States. Bulbs such as E14, E17, E27, and E40 are not as popular in the United States.
How Are Screw-in and Pin-Type Bases Different?
Screw-in and pin-type bases differ in shape, affecting how they’re installed. Screw base bulbs are twisted into a fixture, whereas pin base bulbs feature pins that connect to the fixture.
Do LED Bulbs Have Different Base Types Than Traditional Bulbs?
Modern LED bulbs have base types that are equivalent to traditional bulbs. However, the wattage of traditional and LED bulbs will differ, so you should ensure the LED has the correct comparable wattage or lumen value listed so the light output is similar.
Benefits of Using LEDs
Switching out your traditional bulbs with LEDs leads to:
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Greater energy efficiency.
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Better light output
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Longer lifespans
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Less maintenance
Switch to screw-base LED bulbs now to cut down spending.
Contact Us for Lighting Help
Contact us at Super Bright LEDs for help choosing the correct light bulb for your installation. Call our customer advocates at 866-590-3533 or via our live chat feature.
by Super Bright LEDs Experts
The Super Bright LEDs editorial team provides expert guidance on LED lighting solutions for commercial, industrial, vehicle, and residential use. Their trusted insights help businesses and homeowners make informed lighting decisions.
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