The Ultimate Guide to Standard Light Bulb Bases
When looking to furnish a home, office, or space with fixtures, one element that's often thought about last is the light bulb base. However, when looking for new fixtures or a replacement, it should be one of the first to pick to ensure it's compatible with the bulb, whether you have incandescent light bulbs or LED bulbs in your home. Know whether you have standard light bulbs or non-standard light bulb base sizes.
They play a vital role in dictating each bulb's brightness and color temperature, contributing to a room's ambiance.
With various light bulb bases available, it's imperative that the base you choose matches the bulb size, electrical connection method, and longevity of each bulb.
Otherwise, you could face major risks of flickering bulbs, inconsistent brightness or dimming, overheating, and fires. Uncover everything you need to know about choosing the correct base and bulbs for your home and eliminate these risks.
Types of Light Bulbs
When selecting light bulbs, knowing the base size, decorative element, and usage is essential. Usually, these bulbs are identified by letters and numbers. Letters determine the bulb's shape and any special features, such as a reflector type.
Whereas the numbers are synonymous with the base size, light bulb bases are often measured from their diameter as their widest point. Most of the time, they're measured in eighths of an inch (⅛"). Because of various light bulb base sizes, sometimes the light fittings don't fit new bulbs. Double-check your light bulbs to ensure they fit, whether you're using a new pear-shaped bulb, HID bulb, or any other type.
Example: An A21 light bulb signifies that the base is 21/8th inches in size.
Here are the most common light bulb base types and sizes:
- A (Arbitrary): Represents similar to a standard household bulb. These bulbs are used in chandeliers and kitchens as focused lighting for meal preparation or cooking.
- C (Conic): Similar to a traditional Christmas tree bulb, these bases are best for task and decorative lighting.
- G (Globe): This has a round or circular shape and is best used in an open fixture like a pendant light hanging above a dining table or kitchen island.
- S (Sign): This is straight-sided and is used in signs and advertisements.
- ST (Straight tapered): This is a more vintage-style Edison bulb shape that is good for accent lighting and provides focused illumination.
- T(Tubular): A narrow tube shape perfect for appliance lighting such as refrigerators or evens. It can also be used in cabinets, aquariums and picture lights.
Type A for Standard Household/Arbitrary Light Bulbs: A15, A19, A21, A25
Bulbs in this group are best suited for standard household lighting. They’re seen as appliance bulbs, suitable for various household fixtures such as hallway, ceiling fans, and ceiling lights.
Compatibility-wise, they suit medium screw bases, either E26, E27, or E12, a candelabra base. When looking for this base type, you’ll likely come across A19 the most, which is a standard light bulb size.
However, due to the climate crisis, many are being replaced with CFL twists or spirals due to their energy efficiency, softer glow, and cost-effectiveness.
Note: A19 and E26 bulbs are not the same! Although A19 lamps and fittings have an E26, all E26 bases don’t use A19 bulb heads.
Type B and C for Candle: B10, C7, C9, C15, CA10
This type of bulb resembles a candle flame with a tip at the end. As mentioned earlier, they are primarily used for decorative fixtures such as pendant lights, wall sconces, chandeliers, or accent lights.
The most common base types they connect to are E26, E27, E12 and E17.
Type R for Reflectors and BR for Bulged Reflector Light Bulbs: BR20/R20, BR30, BR40
These bulbs are much less common than other bulbs. They’re best suited for outdoor lighting or recessed lighting. The most common bulbs are BR30 and R20, connecting to E6 or E27 bases.
Type PAR for Parabolic Aluminized Reflector Light Bulbs: PAR16, PAR20, PAR30, PAR36, PAR38
Parabolic aluminized reflector lights are mainly used as outdoor lighting. PAR lights tend to have focused beams illuminating entryways and stages at events or in theaters. The main base types compatible with PAR light bulbs are E26, E26 and G53 screw pins.
Type MR for Multifaceted Reflector or Quartz Reflector Lamp Light Bulbs: MR11, MR16
These reflector bulbs emit a concentrated beam of focused light in a single direction. Because they’re a reflector type, they are used in recessed lighting, desk lighting, and display cases. Compared to other light bulbs, they often use a low-voltage wiring system, making them an excellent choice for driveway lighting, gazebo, and pavement lights.
The most common base type is the MR16, as it’s sleek and like a spotlight. The most common types of bulbs for this are ones with low voltage, such as GX 53 Bi-pi, GZ4 Bi-pin, and GU10 Bi-pin for 120 volts.
Type LFL for Linear Fluorescent Lights and T for Tubular Light Bulbs: T: T7, T8, T10, T12, T14; LFL: T5, T8, T12
T and LFL group lights tend to be tubular, linear, fluorescent, or vintage. Fluorescent light bulbs focus on two dimensions: length and diameter. The most common fluorescent bulbs are:
- T8: 8/8 inch inch diameter
- T5: 5/8 inch diameter
- T12: 12/8 inch diameter
The T8 and T12 are most suited to a kitchen, laundry room, or garage. The most common bases these lights connect with are E26, E26, E12 candelabra, E17, BA15D bayonet and G13 bi-pin.
Type G for Globe Light Bulbs: G11, G14, G16/G50, G60, G25, G80, G30
Finally, globe light bulbs, such as bathroom vanities or statement dining lights, are used for aesthetic purposes. They tend to be more vintage styles with an antique-looking filament in the middle and Edison bulbs.
G lights are mainly compatible with E26, E27 medium screw bases, and E12 candelabra bases.
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Overall, when looking for fixtures for your home, consider the light bulb base, its size, and usage.
While there’s a wide range to choose from, the most common one is Type A for standard household lighting. Beyond that, there’s Type R, PAR, and MR for outdoor lighting.
In addition to looking for the right base, it’s important not to make a common mistake. Check out our post on 7 types of lighting mistakes you must avoid.
FAQs on Light Switch Types
A19 bulbs are standard bulb types compatible with an E26 base. On the contrary, E26 has a broader range of bulbs, which don’t always share the A19 shape. A19 bulbs are used for appliance lighting in hallways or ceilings, whereas E26 bulbs are more suited for outdoor lighting in patio areas.
The standard-size light bulb base is mainly the E26 base, which comes in various types. This base typically has a diameter of 26mm and is compatible with many bulb types. In particular, it is compatible with compact, fluorescent, LED, and incandescent bulbs. E26 is mainly used in household lighting, such as ceiling fixtures, table lamps, and general-purpose bulbs.
Yes, E26 is a standard light bulb base; it allows bulbs of many different types to screw into it. To know if a bulb is compatible, check out the printed instructions and directions on the packaging to review compatibility.
The main difference between the two is that B12 and E12 differ mainly due to their design and type- which influences applications and their compatibility. E12 bulbs have a candelabra screw base with a 12 mm diameter.