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Things You Need to Know About Smart Light Bulb Shapes, Sizes & Codes

Smart Home Lighting 101

When it comes to light bulbs, most people envision a conventional bulb with an upside-down pear shape. Indeed, this classic bulb-type is what most of us grew up using and is what many of us still use today. But just like everything else, light bulbs have evolved. 

Today, you have a variety of different fixtures divided by shape, size, and base type. You only need to take a trip down the lighting aisle of your nearest home improvement store to see how many choices there are! 

Modern light bulbs can be used in a range of fixtures, each with its own size and shape compatibility. While it might seem slightly daunting, the variety of light bulb types is there to help you. 

Seeing a bunch of numbers and letters in a variety of combinations might make you want to stop before you even get started, but how light bulbs are divided is very logical and easy to follow once you know how! 

To help you understand the shapes and sizes you need for your new smart light bulb, we’ve created a useful 101 guide, so you know exactly what you’re looking for next time you need a new light bulb.

What are the different types of smart light bulbs? 

As we mentioned, there is a range of light bulbs, each corresponding to different household fixtures. The lightbulb you use for your bedside lamp will be entirely different from the one used in your bathroom’s recessed fixtures, for example. 

To differentiate bulbs, they are identified by a series of letters and numbers, known as the “light bulb code.” If you understand bulb codes, you will know what kind of bulb you need right away!

The bulb code begins with a letter/letters. The letters are used to indicate the shape or special features such as reflector type. These are some of the most common light bulb shapes you’ll find in your home:

  • A – Arbitrary / standard household incandescent light bulb shape
  • B – Bullet tip
  • BR – Short reflector
  • C – Candle 
  • ER – Extended reflector light bulb shape
  • G – Globe bulb
  • MB – Halogen bulb
  • MR - Quartz Reflector Lamp
  • PAR – Parabolic Aluminized Reflector
  • R – Reflector

Following the letter is a number that corresponds to the bulb’s diameter in eighths of an inch. These codes will tell you if a bulb will fit in your fixture and if it’s the right shape. The main diameter classifications are:

  • 8 = 1 inch
  • 11 = 1.375 inches
  • 16 = 2 inches
  • 20 = 2.5 inches
  • 30 = 3.75 inches
  • 38 = 4.75 inches

Group A: A15, A19, A21 & A25

A-shaped bulbs are the most standard and widely used in the household. In fact, the bulb’s shape hasn’t changed since Thomas Edison assembled the first commercial model in 1879!

Although the shape remains the same, there are variations in size. The number after the letter indicates the diameter of the bulb in eighths of an inch. Some of the most popular include A15, A19, A21, and A25. 

A-shaped bulbs work well in various applications but are most often used in lamps, hallways lights, ceiling lights, ceiling fans, vanity lights, and more. 

Group A shape, size and code differences

A-shaped bulbs come in a variety of sizes, the four most popular include:

A15 bulb: 15/8 = 1-7/8″ diameter

A19 bulb: 19/8 = 2-3/8″ diameter

A21 bulb: 21/8 = 2-5/8″ diameter

A25 bulb: 25/8 = 3-1/8″ diameter

Group G: G11, G14, G50, G30

G-shaped bulbs are dubbed as “globe” or circular bulbs. They have a full, round shape and are available in various sizes. As circular bulbs, the lighting is primarily used in ornamental fixtures and chandeliers. The most common G-shaped bulb is the large G30, which is predominantly used to border bathroom mirrors for vanity purposes. 

Group B & C: B10, C7, C9, C15, CA10

B and C-shaped bulbs resemble a candle flame’s shape - a bulged base that reduces to a rounded tip. However, there is a slight difference: conical (C) bulbs are shaped like a cone, while blunt-tip (B) bulbs have more of a bullet shape. 

These bulbs are widely used in chandeliers, night lights, pendant lights, and Christmas/decorative light strands.

Group BR: BR20 / BR30 / BR 40

BR stands for “bulged reflector.” These bulbs are a wide-angle downlight that usually exceeds 100-degree beam angles. BR bulbs are the first choice when wide-angle lighting is needed, such as in hallway recessed fixtures or above a kitchen work surface.

Group BR: Shape, size and code differences

BR bulbs typically come in three variations. The number on each code refers to the diameter in one-eighths of an inch:

BR20 bulb: 20/8 = 2-1/2″ diameter

BR30 bulb: 30/8 = 3-3/4″ diameter

BR40 bulb: 40/8 = 5″ diameter

Differences between A19 & BR30

The A19 bulb disperses light across a wide area and is an excellent option for floor lamps and hanging ceiling fixtures. That being said, the bulb can be used in almost any household fixture.

Conversely, BR30 light bulbs fit nicely in recessed fixtures. The shape and reflective coating of the BR30 casts direct light, making the bulb ideal for task lighting. 

Read the full differences between A19 and BR30 bulbs here.

Group PAR: PAR16, PAR30, PAR36 and PAR38

PAR-shaped bulbs use a parabolic mirror that produces a highly directional beam of light. PAR bulbs are similar to BR bulbs in the fact that they both are used as downlighting, but PARs do not exceed a beam angle of 45 degrees, making the lighting much more focused. 

The most common PAR bulbs are PAR16, PAR30, PAR36, and PAR42, widely used in spotlights and floodlights.

Differences between PAR30 vs BR30

PAR 30 and BR30 LEDs are a green solution to interior and exterior lighting. Indeed, the two bulbs share significant similarities, but the differences will allow you to make an informed decision about which is best for your purpose. 

BR30 light bulbs provide soft, directional light and are typically found in general household light fixtures, recessed can lighting, and track lighting. Conversely, PAR30 bulbs deliver strong, directional light that is traditionally used outdoors as security lighting.

What Are The Best Light Bulbs For Your Smart Home? 

So long as you have a WiFi network, anyone can install smart lighting! All you need to do is remove old light bulbs and screw in some smart bulbs. Within minutes you’ll be able to enjoy complete control. 

To fasten into your floor lamps and hanging ceiling fixtures, we recommend the A19 smart bulb. The A19 emits omnidirectional lighting, dispersing light evenly across the room.

For directional lighting, BR30 light bulbs and recessed lighting are the best choices. These bulbs point light straight ahead, providing direct task lighting, perfect for hallways, home offices, and above kitchen workstations. 

Once installed, you can adjust brightness, create schedules, add colourful effects, and control bulbs wherever you are through the BAZZ Smart Home app (iOS and Android). Get your hands on BAZZ Smart Home lighting today!