When it comes to lighting your home, picking the right fixture is only half the battle. The other half? Choosing the right light bulb. Whether you’re replacing a burnt out light or upgrading to something more energy efficient or stylish, knowing the differences between bulb shapes, sizes, and bases can make all the difference.
Below, we break down the essentials in a way that’s easy to understand, complete with a handy chart and a friendly walkthrough of how each bulb type works in real-world spaces like your kitchen, bathroom, or entryway.
Common Bulb Shapes and Codes
Here’s a reference chart of some of the most commonly used light bulb shapes and how they’re typically used:
| Bulb Type | Common Codes | Description | Typical Uses |
|---|---|---|---|
| A | A15, A19, A21 | Standard household bulb shape | Lamps, ceiling fans, flush mounts |
| G | G11, G25, G30, G40 | Globe-shaped bulbs | Vanity lights, pendants, decorative fixtures |
| B & C | B10, C7, C9 | Blunt tip or flame shaped | Chandeliers, sconces, decorative lighting |
| BR & R | BR20, BR30, BR40, R20 | Bulged or Reflector types | Recessed cans, ceiling lights |
| PAR | PAR20, PAR30, PAR38 | Parabolic reflector | Track lighting, outdoor floodlights |
| MR | MR11, MR16 | Multifaceted reflector | Display lighting, accent lighting |
| T | T5, T8, T10 | Tubular bulbs | Under-cabinet, picture lights, utilities |
Let’s Take a Closer Look: Common Bulb Shapes and How They’re Used
A Type Bulbs (A15, A19, A21)
These are your everyday workhorses. The “A” stands for “Arbitrary,” but most people just call it a standard bulb. You’ll see A19 bulbs in table lamps, ceiling fans, and flush mounts everywhere. Need something slightly smaller? That’s an A15, often found in appliances like ovens or microwaves. Going bigger? The A21 is typically used in high output fixtures for a bit more brightness.
These are usually paired with an E26 medium screw base, and they are available in every bulb technology from vintage incandescent to ultra-efficient LED.
G (Globe) Type Bulbs (G11, G14, G16, G25, G30, G40)
The “G” is for “Globe,” and these bulbs are all about looks. Their perfectly round shapes make them ideal for exposed bulb designs like bathroom vanities, statement pendants, and glam mirror lighting. A G25 or G30 is probably what you’ve seen lining a vanity mirror or used in decorative bath bars. They also show up in vintage inspired fixtures with visible filaments for that old Hollywood glow.
G-type bulbs typically use E26 medium or E12 candelabra bases. We especially love pairing G bulbs with dimmers to create a cozy, warm ambiance in dining rooms or powder rooms.
G9 and Other Bi-Pin Bulbs (G4, G8, G9)
Despite the name, G9 bulbs are not part of the globe family. In this case, the “G” refers to the type of bi-pin base rather than the bulb’s shape. G9 bulbs are compact and often found in halogen or LED form in modern fixtures like desk lamps, under-cabinet lighting, and some mini pendants. They offer a bright, crisp light and are perfect for small spaces where a traditional bulb wouldn’t fit. Other similar styles include G4 and G8 bulbs, which are also bi-pin types used in specialty or task lighting applications.
These bulbs come in various voltages and are not interchangeable, so it’s important to check your fixture’s specs before replacing them.
B & C Type Bulbs (B10, C7, C9)
Both “B” (Blunt Tip) and “C” (Candle or Conical Tip) bulbs are built for charm. You’ll see B10s and C7s in chandeliers, wall sconces, and decorative candle-style fixtures. The B-shape has a more rounded tip, while the C-shape looks like a flickering flame, perfect for that classic or antique feel.
They usually connect with E12 candelabra bases, though some larger versions may use E26. These are popular in both modern and traditional homes, especially in dining areas or entryways where style matters.
BR & R Type Bulbs (BR20, BR30, BR40, R20)
BR stands for Bulged Reflector, and these are designed to spread light evenly in one direction. You’ll most often find BR30s and BR40s in recessed lighting and ceiling cans. Great for kitchens, hallways, or anywhere you want soft, widespread light.
“R” types (like R20) are similar but have a slightly different beam spread and shape. Most use E26 bases and are available in dimmable LED versions that make them ideal for ambient lighting or even highlighting art and decor.
PAR Bulbs (PAR20, PAR30, PAR38)
These are Parabolic Aluminized Reflector bulbs. Just know they are excellent for focused light. If you’re spotlighting a kitchen island, illuminating landscaping, or need a security floodlight, a PAR38 is your go-to.
They throw a strong, controlled beam and are weather-resistant, making them perfect for both indoor task lighting and outdoor use. They use E26 bases, and LED PAR bulbs are a popular choice for energy conscious homeowners who still want power and punch.
MR Bulbs (MR11, MR16)
Short for Multifaceted Reflector, these compact bulbs are designed for precise, directional lighting. You’ll find them in track lighting, display cases, and accent fixtures. An MR16 is probably lighting up your favorite artwork or bookshelf right now.
MR bulbs often use GU5.3 or GU10 bases. Be sure to double-check, as these aren’t interchangeable. They’re small but mighty and a favorite for layered lighting designs in kitchens, offices, or media rooms.
T Type Bulbs (T5, T8, T10)
“T” stands for Tube, and these are your classic linear bulbs. T8s and T5s are the most common sizes, seen in utility rooms, garages, under-cabinet lighting, and even decorative picture light fixtures.
Modern LED versions of T bulbs offer improved efficiency and color rendering, making them a smart update from older fluorescent models. Some use bi-pin connectors, others screw in with E26 bases, depending on the fixture.
A Quick Lighting Primer: Brightness, Color, and Bulb Types
When shopping for bulbs today, it’s less about wattage and more about what really matters: brightness, color temperature, and efficiency.
- Watts (W) show how much energy a bulb uses, not how bright it is. For example, a 9W LED gives off the same light as an old 60W incandescent.
- Lumens (lm) measure actual brightness. More lumens = more light. Aim for:
- 450 lm for small lamps
- 800 lm for bedrooms and kitchens
- 1600+ lm for large spaces like garages or high ceilings
- Kelvin (K) is color temperature:
- 2700K = warm and cozy (living rooms, bedrooms)
- 3000–3500K = soft white (kitchens, hallways)
- 4000K+ = cool white or daylight (work areas)
Pro Tip: Visit our Milford, MA. or Kingston, MA. showrooms to see the differences in person.
Bulb Types Explained: LED, CFL, Halogen, and Incandescent
With today’s lighting tech, your choices are more versatile than ever. Here’s a side-by-side comparison to help you decide:
| Type | Best For |
|---|---|
| LED | Long life, low energy, dimmable, all styles, your best all-around choice |
| CFL | Budget-friendly for occasional-use lamps |
| Halogen | Crisp, bright light , great for task lighting |
| Incandescent | Warm glow for vintage fixtures (but being phased out) |
Need help finding the right bulb for your fixture? Stop into either of our showrooms in Milford, MA. and Kingston, MA. and speak with one of our trained Purple People lighting pros. Or shop online at Light ‘N Leisure “The Purple Buildings” and sign up for coupons to save on every order. we stock a wide range of high-quality LED bulbs, including smart, vintage-style, and outdoor-rated options, and our Purple People are always ready to help you find the perfect fit.
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