Light bulb Size : What are the different and standard bulb sizes?

Light bulbs come in several varieties of shapes, sizes and standard wattages. Before buying a light bulb, it’s important to understand which type will be suitable for your home or business and how much illumination is required. Light bulb size is expressed by a combination of letters and numbers. The letter is the series, the numbers indicate the diameter of the bulb shape. The most commonly used household bulb is the A-19 (in US) or A-60 (UK bulb sizing). The bulb is “A” type and the diameter would be 2 3/8″

Light bulbs: What are the different light bulb sizes?

Where can I find out the light bulb size I need?

A bulb’s code number is made up of a letter or letters followed by a number. The letter represents the bulb’s shape, and the number represents its diameter in eighths of an inch. The A-19 is the most commonly used household bulb. The light bulb is “A” type, with a diameter of 23/8″. A 65BR40 is a 5 watt reflector with a power rating of 65 watts “in circumference.

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In fact, there are different types of lighting such as track lighting, night lights, landscape lighting, decorative lighting, garden lighting, residential lighting, hard-edged lighting, and more. 

How to measure a Light bulb size?
How to measure a Light bulb size?

Light Bulb Size Chart and Series 

We must understand that the light bulb series shows the shape and a number code shows the light bulb diameter in 1/8th inch and millimeters (mm). The type of bulb is the determinant. Our size charts will be organized via various sizes, bases, type of light, and intended use. 

Example of Light bulb series and their sizes
Example of Light bulb series and their sizes

Check the below table with Light bulb series, the code of the most popular or standard light bulb in US and UK and the dimensions.

Are US and UK light bulbs the same?

No they are not the same. In the U.K. they are designed to run on 240v whereas in the US, they run on 120v.

CODEDIAMETER IN (Inches and mm)LENGTHS IN (inches and mm)
A SeriesA19 (US) or A6 (UK)60 mm 2.4 inches3.9 – 4.3 inches (99.06 – 110 mm)
B Series B1031.75 mm 1.3 inches3.5 – 4.4 inches (90 -113 mm)
C SeriesC928.58 mm 1.1 inches3.5 – 3.9 inches (90 – 100 mm)
CA Series CA1031.75 mm 1.3 inches3.5 – 3.9 inches (90 – 100 mm)
R Series R50159 mm 6.3 inches3.4 inches (86 – 87 mm)
R SeriesR63200 mm 7.9 inches3.9 – 4.0 inches (100 – 102 mm)
R/BR Series R80254 mm 10 inches4.4 – 4.8 inches (112 – 118 mm)
PAR SeriesPAR1650.8 mm 2 inches2.0 – 2.2 inches (50 – 55 mm)
PAR Series PAR20 63.5 mm 2.5 inches2.5 – 8.9 inches(64 -89 mm)
AR SeriesPAR36111 mm 4.4 inches2.3 – 2.6 inches (58 – 66 mm)
PAR Series PAR36120.65 mm 4.8 inches5.3 – 5.4 inches (134 – 136 mm)
MR Series MR1135 mm 1.4 inches1.5 – 1.7 inches (37 42 mm)
MR Series MR1650.8 mm 2 inches1.8 – 2.1 inches (45 – 53 mm)
G Series G25 (US) or G80 (UK)80 mm 3.2 inches120 mm 4.7 inches
G SeriesG30 (US) or G95 (UK)95 mm 3.7 inches140 mm 5.5 inches
G Series G40 (US) or G125 (UK)125 mm 4.9 inches6.5 – 6.7 inches(165 – 170 mm)
T Series T3030 mm 1.2 inches8.9 – 11.8 inches (225 – 300 mm)
T Series T4545 mm 1.8 inches110 mm 4.3 inches
T SeriesT516 mm 0.6 inches12.0 – 57.6 inches (305 -1463 mm)
T Series T826 mm 1.0 inches13.0 – 48.0 inches (330 – 1220 mm)

Light Bulbs Replacement Guide (video)

A complete guide about replacing light bulbs of different types and sizes by

Light Bulb Sizes – Shapes, and Codes

A Series. 

They can be called Standard bulbs, general lamp service (GLS), or arbitrary and typically used at home. The A-Series traditional bulbs are used as kitchen lamps, porch lamps, ceiling lamps, floor and table lamps, and reading lamps. 

The A Series is popular due to its light bulb shapes and smart bulbs. The bulbs are used with base types screw (E27, E14) or bayonet (B22) and have a wide range of uses. 

                            A19 or A60 Light Bulb Size Chart 
Common Lengths in inches and mm3.9 – 4.3 inches (100 – 110 mm)
Diameter in mm and inches60 mm (2.3622 inches)
Light bulb code A19 (US) or A60 (UK)
Diameter 1/8th inch2 3/8″ (10 / 8 diameter)

A-series bulb types

  • Halogen bulbs
  • Incandescent Lights 
  • Compact Fluorescent
  • LED Filament Bulbs

B/C/CA Series 

We start by understanding what the B/C/CA series stands for:

B – Blunt

C – Conical or Candle 

CA – Candle Angular 

They usually produce light similar to the candle flames., however, they are smaller in size compared to other types of bulbs.  They come in different candle bulb shapes, for example, CA is similar to candle flames with a curved tip, C and B are stylized and blunted. They are used for holiday lighting, artificial candles, chandeliers, decorative events, and night lighting. 

Some common B, C, and CA types include light bulb bases like E27, B22, B15, SES14, and CES12. 

 Common B, C, and CA
Light Bulb CodeB10C9CA10
Common Lengths in mm and inches 90 – 113 mm 3.5 – 4.4 inches90-100 mm 3.5 – 3.9 inches110-130 mm 4.3 – 5.1 inches
Diameter in mm and inches31.75 mm 1.3 inches28.58 mm 1.1 inches31.75 mm 1.3 inches
Diameter in 1/8th inch10/8 (1 1/4″)9/8 (1 1/8″)10/8 (1 1/4″)

R and BR Series 

Let us start by understanding what R and BR series stands for: 

R – Reflector

BR – Bulged Reflector 

They are commonly used as security lights, track lights, display lights, smart bulbs or recessed lights. 

They produce a wide beam angle ideal for residential and commercial settings. 

 Common R/BR Series
Light Bulb Code R50R63R80
Common Lengths in mm and inches 86 – 87 mm 3.4 inches100 – 102 mm 3.9 – 4.0 inches112 – 118 mm 4.4 – 4.6 inches
Diameter in mm and inches159 mm 6.3 inches200 mm 7.9 inches254 mm 10 inches
Diameter in 1/8th inch50/8 (6 1/4″)63/8 (7.86″)80/8 (10″)

MR Series. 

MR stands for Multifaceted Reflector are larger than the other light bulbs discussed above. They have a multi-faceted reflective lining. Their base typesGU4, GX5.3, and GU10. 

The fact that they are multi-faceted makes them produce directional beams of light. They also emit narrow or wide spotlights. 

They are commonly used for landscape lighting, desk lamps, track lighting, display cases, and recessed lighting. 

Common MR Series Bulbs Size Chart 
Light bulb codeMR11MR11
Common Lengths in mm and inches50 – 55 mm  2.0 – 2.2 inches64 – 89 mm  2.5 – 8.9 inches
Diameter in mm and inches50.8 mm 2 inches63.5 mm  2.5 inches
Diameter in 1/8th inch 16/8 (2”)20/8 (2.5”)

G Series

G series means Globe series bulbs. They come in a wide range of sizes and are mostly spherical. There are small G series bulbs with enclosed fixtures. The Large G has carbon or LED filaments, making them look appealing to the eye. They can fit in different settings such as pendant lamps, vanities, small enclosed fixtures, decorative fixtures, and chandeliers. 

Common G Series Bulbs Size Chart
Light bulb code G25 (US) or G80 (UK)G30 (US) or G95 (UK)
Common Lengths in mm and inches120 mm  4.7 inches140 mm 5.5 inches
Diameter in mm and inches80 mm  3.1 inches 95 mm 3.7 inches
Diameter in 1/8th inch 25/8 (3.14”)30/8 (3.70”)

T Series 

T Series stands for Tube or Tubular bulbs and comes in various sizes and shapes. The fluorescent tubes are similar to test tubes. Their light bulb base sizes include G13, G5, E12, and E27. They are mostly used for garage lighting, pendant lamps, chandeliers, warehouse lighting, sconces, and chandeliers.

Common T Bulb Size Chart 
Light Bulb CodeT30T45
Common Lengths in mm and inches225 – 300 mm 8.9 – 11.8 inches110 mm 4.3 inches
Diameter in mm and inches30 mm 1.2 inches 45 mm 1.8 inches
Diameter in 1/8th inch(1.18”)(1.77”)

AR and PAR Series 

Let’s start by understanding what AR and PAR series stands for: 

AR – Aluminum-faceted Reflectors

PAR – Parabolic Aluminized Reflectors

The AR and PAR series range base types include B22, E27, E14, G53, G12, and GU10, which are ideal for commercial and residential settings. They are mostly used as architectural and landscaping lights, recessed lights, decorative floodlights, track lights, and security lights. 

AR and PAR series have reflective materials and are shorter than R and BR, making them fit for light fixtures.

Common AR and PAR Series 
Light Bulb Code PAR16PAR20
Common Lengths in mm and inches50 – 55 mm  2.0 – 2.2 inches64 – 89 mm 2.5 – 3.5 inches
Diameter in mm and inches50.8 mm 2 inches63.5 mm 2.5 inches 
Diameter in 1/8th inch16/8 (2″)20/8 (2.5″)

Light Bulb Size Explained (video)

Light bulb size and types explained by AMRE Supply

Frequently Asked Questions (FAQ)

What is the most popular Light bulb size?

The A19 (US) or A60 (UK) is the most standard light bulb size. (other Type A Light Bulbs like A15, A19, A21 & A25 are also common sizes) These lamps fit medium screw bases (E26 and E27) or the candelabra base (E12).

Light bulb
Light bulb codeA60 (UK) or A19 (US)
Diameter in millimeters60mm
Diameter in one-eights of an inch19/8 (2 3/8″ diameter)
Length in mm and inches100-110mm (3.9-4.3 inches)

Conclusion on light bulb sizes

Having an illuminating bulb in your living room could be fun and aesthetic. As discussed in this light bulb size chart guide, there are different types of lighting. You will discover that different lightings or bulbs serve different purposes and come in different shapes and sizes. 

Choosing the right bulb is upon you based on the purpose intended. You also need to ensure that the quality is great and perfect. 

If you enjoyed reading this sizing guide, please don’t hesitate to leave a comment below!

Picture in this post by Patrick Tomasso on Unsplash

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