Common Light Bulb Types Explained: G4, G9, E12, E14, E26, E27 & Integrated LED
Choosing a light fixture is exciting—but choosing the right bulb type can quickly become confusing. Many shoppers discover that once a bulb burns out, they’re unsure what replacement to buy, or whether different bulb types are interchangeable.
This guide explains some of the most commonly used light bulb types in modern lighting—G4, G9, E12, E14, E26, E27, and Integrated LED—in clear, practical terms. By the end, you’ll know exactly what they are, how they differ, and how to choose the right one with confidence.
Why Light Bulb Type Matters
A bulb’s type determines:
- Whether it physically fits your fixture
- What voltage it operates on
- How bright and efficient it is
- Whether it can be replaced in the future
Using the wrong bulb can lead to poor performance, flickering, overheating, or damage to the fixture. Understanding bulb types helps you avoid costly mistakes and ensures safe, long-lasting lighting.
G4 Bulbs: Compact Low-Voltage Lighting
G4 bulbs are small, bi-pin bulbs with two thin pins spaced 4mm apart.
Key Characteristics
- Usually low voltage (commonly 12V)
- Very compact size
- Available in halogen and LED versions
Common Uses
- Cabinet lighting
- Accent lighting
- Small decorative fixtures
What to Know
G4 bulbs are not interchangeable with G9 bulbs. They often require a transformer, and replacing them with the wrong voltage bulb can cause immediate failure.
G9 Bulbs: Small but Powerful
G9 bulbs also use two pins, but they are thicker and looped, designed for higher voltage.
Key Characteristics
- Typically operates on line voltage (120V in the U.S.)
- Brighter than G4
- Compact but sturdy design
Common Uses
- Wall sconces
- Pendant lights
- Modern decorative fixtures
What to Know
Despite their similar appearance, G4 and G9 are not compatible. Always check the socket and voltage requirement before purchasing.
E12 Bulbs: The Candelabra Base
E12 bulbs use a small Edison screw base with a 12mm diameter.
Key Characteristics
- Often called “candelabra bulbs”
- Designed for decorative lighting
- Common in North America
Common Uses
- Chandeliers
- Wall sconces
- Accent fixtures
What to Know
E12 bulbs are smaller than standard bulbs and cannot be replaced with E26 bulbs. They often prioritize ambiance over high brightness.
E14 Bulbs: The Small Edison Screw (SES)
E14 bulbs look similar to E12 but are slightly larger.
Key Characteristics
- 14mm screw base
- More common in Europe and Asia
- Often found in imported fixtures
Common Uses
What to Know
E12 and E14 are not the same, even though they look close in size. They are generally not interchangeable without adapters, and adapters are not always recommended for long-term use.
E26 Bulbs: The U.S. Standard
E26 bulbs are the most common bulb type in the United States.
Key Characteristics
- Medium Edison screw
- Wide availability
- Supports many wattages and styles
Common Uses
What to Know
E26 is the default bulb base for most American homes. It offers the greatest flexibility in brightness, color temperature, and smart lighting options.
E27 Bulbs: The International Standard
E27 bulbs are nearly identical to E26 in size but are designed for different voltage standards.
Key Characteristics
- 27mm screw base
- Common outside North America
- Slightly larger than E26
What to Know
In many LED fixtures, E26 and E27 bulbs can be used interchangeably if the voltage is compatible. However, checking manufacturer recommendations is always best.
Integrated LED: Built-In Light Sources
Integrated LED fixtures do not use replaceable bulbs. Instead, the LED light source is built directly into the fixture.
Key Characteristics
- No bulb replacement required
- High efficiency
- Designed as a complete lighting system
Common Uses
- Modern ceiling lights
- Custom chandeliers
- Minimalist and architectural fixtures
What to Know
Integrated LED fixtures offer long lifespans and consistent performance, but when the LED eventually reaches the end of its life, the entire light module—or fixture—may need replacement. Quality design and proper thermal management are critical here.
Quick Comparison Overview
| Type | Voltage | Replaceable | Typical Use |
|---|---|---|---|
| G4 | Low Voltage (12V) | Yes | Accent lighting, cabinets |
| G9 | Line Voltage | Yes | Wall lights, pendants |
| E12 | Line Voltage | Yes | Chandeliers, decorative lighting |
| E14 | Line Voltage | Yes | Decorative fixtures (mainly EU-style) |
| E26 / E27 | Line Voltage | Yes | Standard ceiling, pendant, lamps |
| Integrated LED | Varies | No | Modern and custom lighting fixtures |
How to Choose the Right Bulb Type
When buying a light fixture or replacement bulb, always:
- Check the socket type
- Confirm voltage requirements
- Consider brightness (lumens, not watts)
- Decide on color temperature
- Verify dimming compatibility if needed
If you’re unsure, consulting a professional or referencing the fixture’s specifications is the safest approach.
Final Takeaway: What You Really Need to Know
Not all bulbs are created equal. While some types may look similar, small differences in size, voltage, and design can have a big impact on performance and safety. Understanding G4, G9, E12, E14, E26, E27, and Integrated LED lighting empowers you to make smarter, longer-lasting lighting choices—and avoid frustration down the road.
Good lighting starts with the right foundation, and that foundation is knowing your bulb type.
FAQ
1. What is the difference between G4 and G9 bulbs?
G4 bulbs are low-voltage pin bulbs, commonly used in small accent or cabinet lighting.
G9 bulbs are line-voltage bulbs with thicker looped pins and are often used in wall lights and pendants. They are not interchangeable.
2. Are E12 and E14 bulbs the same?
No. E12 and E14 bulbs look similar but have different base diameters.
E12 is mainly used in North America, while E14 is more common in Europe. They are generally not interchangeable.
3. Can E26 and E27 bulbs be used interchangeably?
In many LED applications, E26 and E27 bulbs can be used interchangeably if the voltage is compatible.
However, it’s always best to follow the fixture manufacturer’s recommendation.
4. What is an integrated LED light fixture?
An integrated LED fixture has a built-in light source rather than a replaceable bulb.
It offers high efficiency and long lifespan but does not allow bulb replacement.
5. Which bulb type is best for chandeliers?
Chandeliers commonly use E12, E14, or integrated LED designs, depending on the style and size of the fixture. Smaller bases help maintain elegant proportions.
6. How do I know which bulb type my fixture uses?
Check the socket marking, product specifications, or original packaging.
If unsure, consult a professional before installing a replacement bulb.