Bulb Base Reference Chart - Common Light Bulb Base Types Explained
E26 (Medium Screw Base)
The E26 base is the most common in the US, also known as a standard light bulb base. Widely used in incandescent, LED, CFL, and halogen bulbs, this base fits most household fixtures from ceiling lights to table lamps.
- Usage: General home lighting
- Compatibility: Standard household fixtures
E27 (European Medium Screw Base)
Similar to the E26, the E27 base is common in Europe. While almost identical in size, it's essential to ensure your fixture can accommodate this slightly different base.
- Usage: General home lighting in Europe
- Compatibility: European fixtures
E12 (Candelabra Screw Base)
The E12 base is often found in smaller, decorative bulbs used in chandeliers, sconces, and nightlights.
- Usage: Decorative lighting
- Compatibility: Chandeliers, sconces
E17 (Intermediate Screw Base)
Less common than the E26 or E12, the E17 base is typically used in specialty fixtures like appliance lights and desk lamps.
- Usage: Specialty lighting
- Compatibility: Appliances, small fixtures
If you have a light fixture with an E17 intermediate base light socket and you are having a hard time finding the right bulb or would like to use a more common light bulb, you can get an adopter which will enable you to use the E12 candelabra bulbs or the medium E26 base bulbs.
GU10 (Twist-Lock Base)
The GU10 base features two pins that lock into place with a twist. Commonly used in track lighting and recessed downlights.
- Usage: Spotlights, track lighting
- Compatibility: GU10 fixtures
MR16 (Bi-Pin Base)
MR16 bulbs use a bi-pin base and are often found in accent, track, and recessed lighting. They are popular for their focused beam and compact size.
- Usage: Accent lighting, recessed lighting
- Compatibility: MR16 fixtures
Comparing Light Bulb Base Types
Understanding the differences between light bulb bases can help you choose the right one for your fixture. Here’s a quick comparison:
| Base Type | Common Use | Compatibility | Energy Efficiency |
|-----------|---------------------|---------------------------------------|-------------------|
| E26 | General home lighting | Most household fixtures | High with LED/CFL |
| E27 | European lighting | European fixtures | High with LED/CFL |
| E12 | Decorative lighting | Chandeliers, sconces | Moderate |
| E17 | Specialty lighting | Appliances, desk lamps | Moderate |
| GU10 | Spotlights | Track lighting, recessed downlights | High with LED |
| MR16 | Accent lighting | Accent, track, recessed lighting | High with LED |
FAQs on Light Bulb Base Types
Q: Can I use an E27 bulb in an E26 socket?
A: Yes, E27 bulbs can generally be used in E26 sockets, but it's important to check the fixture's voltage requirements.
Q: What should I do if I can't find a bulb for my E17 base?
A: You can use an adapter to fit more common E12 or E26 bulbs into an E17 socket.
Q: Are GU10 and MR16 bases interchangeable?
A: No, GU10 and MR16 bases are not interchangeable. Each requires a specific fixture.
The following chart references the diameter of the light bulb
Tips for Buying LED Filament Bulbs
When choosing an LED bulb it’s important to understand lumens (light output). Until LED bulbs came we were looking at wattage to know how much light the bulb would give out. With LED bulbs this does not work. We have to look at lumens to know how much light the bulb will give out. To make this transition easier many manufacturers will list the wattage equivalent on the bulbs specs. For example, a 5-watt LED bulb may be labeled as a 60-watt equivalent.
And if they don't state the wattage equivalent, here is a quick lumen guide list:
- To replace a 75W bulb, choose a bulb with about 1100 lumens.
- To replace a 60W bulb, choose a bulb with about 800 lumens.
- To replace a 40W bulb, choose a bulb with about 450 lumens.
- To replace a 25W bulb, choose a bulb with about 200 lumens.
Now let's look at the light color or what is known as the color temperature:
Unlike incandescent bulbs, with LED bulbs you have the option to choose the color temperature of the light. This is measured by a Kelvin scale where lower numbers mean yellow candlelight and higher numbers mean blue daylight. See chart:
Another fact to keep in mind is the dimming capabilities of those LED bulbs. Not all of them are dimmable, unlike the incandescent Edison Bulbs. The ones that are dimmable are restricted to certain low-voltage dimmers specifically designed for LEDs. There are also limitations to the amount of bulbs each dimmer could handle. The older standard dimmers will most likely not work properly on most Filament Edison LEDs.
Tips for Buying Compact Fluorescent Bulbs
Compact Fluorescent Lamps (CFLs) are energy-saving replacements for incandescent light bulbs. Below you will find information to assist you in choosing the right bulb.
How do incandescent bulbs and CFLs compare?
Incandescent bulbs produce light by passing electricity through a small wire filament, heating it until it glows. Compact fluorescent lamps use an efficient chemical reaction to produce light, which requires 66%-75% less electricity to produce the same light output as a comparable incandescent bulb. CFLs are also cooler than incandescent bulbs and last considerably longer. CFLs are available in a familiar range of styles and colors to suit different applications, including standard round, candelabra, flood, track, three-way, dimmable, indoor, and outdoor.
What are the different base types of compact fluorescent bulbs?
CFLs are available in three base types: screw base, pin base, and GU24.
- Screw base bulbs, which have the familiar Edison screw socket, are the type used to replace existing incandescent bulbs. Simply swap out the old incandescent bulb for your new CFL and save significant energy costs.
- Pin-base CFLs have small plastic bases with two or four pins and are designed to be used with separate ballasts mounted in fixtures designed for pin-base CFLs.
- The GU24 socket and base system is designed to replace the Edison socket and base in energy efficient lighting fixtures to match the newest ENERGY STAR requirements. Fixtures that use GU24 bulbs are designed to avoid backward compatibility with screw base bulbs, guaranteeing higher energy efficiency.
How long do the bulbs last?
CFLs can last 8,000 to 15,000 hours depending on quality while incandescent bulbs typically last 750 to 1,000 hours. What types of lighting can I get with CFLs?
While many people are familiar with the bluish-white flicker of a hospital hallway illuminated by old-style 48-inch fluorescent bulbs, in fact a broad range of colors are available. The common colors range from a "soft white", to a medium white to a "daylight" color that has more blue and less yellow. Additionally, a range of novelty colors are available (red, black, green, etc.) including yellow, which is ideal for outdoor lighting as it does not attract insects. For indoor lighting of living spaces, choose a cooler temperature light, while for garages or work areas use the brighter and bluer daylight CFLs which cast a wider area of illumination. If you are using a dimmable fixture, you will need to purchase a CFL specifically designed for dimming; standard CFLs do not have that function. How do I dispose of CFLs?
Some municipalities allow for regular trash disposal while others require disposal at a hazardous waste facility or recycling facility. Contact your local waste collection service or municipality for the policy in your area.