What are Type A Light Bulbs? How to identify Type A light bulbs?

  • Home Decor 101
  • Posted by: carson-rutz
  • Jun 16, 2024

What is a type A lamp light bulb? Have you ever wondered how to navigate the world of type A light bulbs? With the vast array of light bulb types available on the market, it can be overwhelming to navigate the various options and choose the most suitable one for your needs. In this comprehensive guide, we will explore the different types of A light bulbs, from understanding the various types of A light bases and fitting types to identifying the right fit for your fixtures.

What is a Type A Lamp Bulb?

What is a type a light bulb? (source: lohah led)
What is a type a light bulb? (source: lohah led)

The A-series light bulb, also called "A bulbs," is the quintessential pear-shaped bulb widely used for general household fixtures such as table lamps or ceiling fixtures since the early 1900s. 

Its design includes either an Edison screw or bayonet cap base, with the number following the A denoting the bulb's major diameter in either inches or millimeters depending on the region. Different bulb types of type A consist of A15, A19, A21, and A25, with the most common being A19.

Different Type A Light Bulbs: A15, A19, A21, A25

What is a type A lamp bulb? Type A light bulb, also known as standard incandescent bulbs, is the most widely recognized and commonly used light bulb type. These different bulb types feature a classic pear-shaped design and are available in a range of sizes, including A15, A19, A21, and A25.

Type A light bulbs Size Use Price
A15 15/8 in (1.875 in)
  • Small desk lamps 
  • Vanity lights
A17 17/8 in (2.125 inch)
  • Standard household bulbs 
  • Fixtures
  • A range of fixtures
  • Fits a wide variety of standard sockets
A19 19/8 in (2.375 in)
  • Standard household bulbs 
  • Fixtures
  • Overhead lights
A20 20/8 ins (2.5 in)
  • Pendants
  • Table lamps
  • Many standard light fixtures
A21 21/8 in (2.625 in)
  • Larger fixtures 
  • Areas that require more brightness
A23 23/8 in (2.875 in) Spaces that require significant illumination $14.51
A25 25/8 in (3.125 in)
  • Larger lamps 
  • Outdoor fixtures

*Note: Please note that prices as shown are valid at the time of publication and are subject to change without prior notice.

Type A Light Base & Fitting Types

In addition to the different bulb types and shapes of a light bulb, the type of cap or base is an important factor to consider when selecting a replacement. Here are some of the most common cap-fitting types:

Different types of type a light fitting (source: 12vmonster)
Different types of type a light fitting (source: 12vmonster)
Type A Light Fittings Features Usage 
E10 (MES or Miniature Edison screw)
  • Diameter: 10 mm
  • Typical wattage range: 3 - 15 W
  • Voltage range: 2 - 24 V
  • Ancient chandeliers
  • The majority of small lamp applications
  • Indicating panels

(Mini candelabra)

  • Diameter: 11 mm
  • Typical wattage range: 25 - 40 W
  • Voltage range: 110 - 120 V
Standard household bulbs

  • Small halogen bulbs
  • Use these adapters to install new LED lights into older styles halogen fixtures

(Small candelabra base)

Known as “Medium” or “Standard” base

  • Diameter: 12 mm
  • Typical wattage range: 40W or less
  • Voltage range: 110 - 120 volts
  • Uncommon fitment
  • Found in the US, particularly in old or imported fittings
  • Night light bulbs
  • Decorative light bulbs for chandeliers and bathroom mirrors

(SES or Small Edison Screw)

  • Diameter: 13 mm
  • Typical wattage range: 15 - 60 W
  • Voltage range: 220 - 240 V
  • Common size used throughout Europe and the UK
  • Most small light fittings
  • Bedside table lamps 
  • Wall lights 
  • Chandeliers

(Intermediate base)

  • Diameter: 17 mm
  • Typical wattage range: 13 - 75 W
  • Voltage range: 110 - 120 V
  • Office desk lamps 
  • Appliance Bulbs
E26/E27 (standard medium screw base)
  • Diameter: 26 mm/ 27 mm
  • Typical wattage range: 100 - 150 W
  • Voltage range: 120 - 240 V
  • E26: standard 120-volt American base
  • E27: Europe’s variant
  • Not used in delicate light fittings like chandeliers and old fittings 
  • Most standard light fixtures
  • E26 bulb may fit into E27, and vice versa.
  • Although sockets are interchangeable, their voltage ratings differ
EX39/E39 (U.S.)/E40 (EU)

(The EX39 fitting's screw base features a longer tip)

  • Diameter: 39 mm / 40 mm
  • Typical wattage range: High-wattage lamps, typically with 100W, 200W, or 300W bulbs
  • Voltage range: 100 ~ 240 V
  • 39/EX39 bases are primarily used in North America
  • E40 bases are popular in Europe and other markets
  • Bulbs for EX39 bases often include protective shields, allowing them to be utilized in both open and closed fixtures
  • Streetlights,
  • High-intensity discharge lamps

When replacing a lightbulb, it's important to know what kind of cap fitting to choose to make sure it works with the lighting fixture you already have. It's essential to match the cap fitting of the new bulb with the socket of the fixture for a secure and safe installation.

*Some important tips: 

A-group bulbs, which are commonly used for regular domestic lighting, work well in a variety of fixtures such as hall lights and ceiling fans. They typically fit medium screw bases (E26 and E27) or candelabra bases (E12). The A19, the standard bulb size, is popular. However, CFL Twists or Spirals are progressively replacing A19s due to their higher energy efficiency.

A19 lamps and light fixtures come with E26 bases, but it's important to understand that not all E26 bases are meant for A19 bulb types. When purchasing standard light bulbs, it's crucial to be aware of this distinction to ensure compatibility with your fixtures.

How to Identify Type A Light Bulb?

Measure the diameter of the a light bulb to determine exactly its size (source: norb lighting)
Measure the diameter of the a light bulb to determine exactly its size (source: norb lighting)

Identifying the right Type A light bulb is essential when replacing or upgrading your lighting fixtures, as it ensures a proper fit and compatibility. There are a few straightforward methods to determine the size you need: 

Firstly, the size of a light bulb is typically determined by its diameter, which is measured in eighths of an inch. For example, a light bulb with a diameter of 2.25 inches would be referred to as an "A19" bulb, as 19/8 inches is equal to 2.375 inches. 

Another option is to check the product information or packaging, where the size is often clearly labeled. If you prefer a more convenient approach, there are plenty of bulb size guides available online to help you match your bulb's dimensions with the correct size designation. 

And if you're feeling unsure or need personalized assistance, don't hesitate to reach out to a lighting professional. They can provide experienced guidance targeted to your unique requirements, ensuring that you choose the appropriate Type A light bulb for your fixtures. 

Type A Light Bulb in Light Fixtures

Type A lamps are common in household appliances like bedside lamps, hallway sconces, and living room floor lamps. Here is a list of some popular type A LED lamps in light fixtures in your houses, along with their effects, and usage. 

Type of lamps Effects Use
Pendant light 

Pendant light 


  • Flexible in style
  • Adds decorative flair to room decor
  • Creates ambient lighting
  • General lighting
  • Centerpiece, accent 
  • Task lighting
Recessed light

Recessed light

  • Ambient lighting gives a modern look and spaciousness
  • Provides subtle ambient lighting throughout rooms.
  • Creates a modern, minimalist aesthetic
Used as supplement lighting


  • Classic ambient lighting
  • Elevates room decor with grandeur.
  • Enhances ambiance with sparkling brilliance
Bedroom halls, living room, or sometimes functional room
Floor lamps 

Floor lamps 

  • Warm ambience
  • Adds focal point to room
  • Living room 
  • Bedroom
Accent lights 

Accent lights 

  • Adding focus and exposure to a singular
  • Enhances mood and ambiance with subtlety
  • Adds depth and dimension to room decor
Highlights artwork or architectural features beautifully
Direct/indirect pendant lights 

Direct/indirect pendant lights 

  • General lighting
  • Enhances visual comfort with balanced brightness
Task lighting, mostly for working spaces and kitchen.


In conclusion, understanding the different types of light bulbs, especially type A light bulb including their shapes, base sizes, and fitting types, is essential for selecting the right bulb for your lighting needs. Additionally, being aware of common cap fitting types and ensuring compatibility with your fixtures will ensure a secure and safe installation. By considering these factors, you can confidently choose the perfect light bulb for any room in your home or business.


What are the alternatives to Type A light bulbs?

If you're looking for alternatives to Type A light bulbs, you have a few options to choose from. CFLs, LEDs, and halogens are all excellent choices with higher energy efficiency and longer lifespans.

How do I dispose of a Type A light bulb?

When it comes to disposing of a Type A light bulb, the best way is to place it in a recycling bin. This ensures that it is properly recycled and prevents any harmful materials from ending up in landfills. But how about other sorts of light bulbs? Check out our article about how to dispose of lamp responsibly.

Can Type A light bulbs be used outdoors?

No, Type A light bulbs are not designed for outdoor use. This means they are not built to withstand the elements and may be damaged or pose a safety risk if exposed to moisture or extreme temperatures. 

What is the colour temperature of a Type A light bulb?

The color temperature of Type A light bulbs can vary, but generally, look for bulbs with a Kelvin temperature of 2700K to 3000K for a soft white light.

How much energy does a Type A light bulb use?

A Type A light bulb typically uses around 60 watts of energy. This energy-efficient option provides ample illumination while helping to reduce electricity costs. It's always a good idea to consider the wattage of a light bulb when selecting the right one for your space, ensuring you strike the perfect balance between brightness and efficiency.

What is the average lifespan of a Type A light bulb?

On average, the average lifespan of a Type A light bulb is about 1,000 hours, offering reliable illumination for your home or workspace.


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