Types of Light Bulbs Based On Shapes and Sizes – Reference Guide
The most commonly used light bulb classification is based on how light gets emitted. It may be LED, Incandescent, CFL, Halogen, etc. But there is another classification which is based on the bulb’s shape and size.
There are more than a hundred different light bulbs that are classified under 18 different categories depending on their shape. So, it is necessary to understand this classification to get the right type of light bulb for your needs.
Therefore, we are presenting this reference guide on the different types of light bulbs based on their shapes and sizes.
Different Types of Light Bulb Shapes and Sizes
As we mentioned earlier, 18 types of light bulbs are categorized based on their shapes. Each category has an alpha-numeric code to denote its shape and size. The categories are:
- A – Series
- B – Series
- BT- Series
- BR – Series
- C – Series
- CA – Series
- E – Series
- ED – Series
- F – Series
- G – Series
- T – Series
- PS – Series
- R – Series
- MR – Series
- AR – Series
- PAR – Series
- S-Series
- ST-series
What does the Alphabet mean in Light Bulb Code?
The alphabet mentioned above denotes the shape of the light bulbs. It is an abbreviation of the name that explains the bulb’s shape. Here is a list of light bulb shapes and the meaning for their alphabetical code:
| Bulb Series | Shape |
|---|---|
| A | Arbitrary |
| B | Bulged |
| BT | Blown Tubular |
| BR | Bulged Reflector |
| C | Candle |
| CA | Candle Angular |
| E | Ellipsoidal |
| ED | Ellipsoidal Dimple |
| F | Flambeau |
| G | Globe |
| T | Tubular |
| PS | Pear Shaped |
| R | Reflector |
| MR | Multifaceted Reflector |
| AR | Aluminum Faceted Reflector |
| PAR | Parabolic Aluminized Reflector |
| S | Straight sided |
| ST | Straight Tapered |
A – Series Light Bulbs
A-type or Arbitrary shaped light bulbs are widely used in common household lightings. The shape is denoted as arbitrary because it has a spherical structure at the top and it gradually shrinks down to a tube-like structure near the base. Since there are two different profiles in the bulb’s shape, it is named as Arbitrary.
Typical sizes in the A-series bulbs are:
- A15
- A17
- A19
- A21
- A23
- A60
The numbers near the “A” denote the diameters of the bulb. We have explained how the diameter is measured for light bulbs when discussing how A15 and A19 bulbs differ. We recommend reading it for more technical information on how the size of light bulbs is measured.
You can find A-Series bulbs to be used in ceiling lamps, table lamps, closet areas, etc. Some sizes of the A-series bulbs, like the A15 bulbs, are used in ovens and refrigerators too.
B-Series Light Bulbs
B-series bulbs have a bulged shape that resembles an oval profile. It is also a bit elongated and has the following sizes:
- B8
- B10
- B11
- B13
B-type bulbs are used in decorative lighting fixtures and chandeliers.
BT-Series Bulbs
Blown tubular bulbs have a mixed shape. They have a circular head, a bulged body, and a tubular stem near the base.
Common BT-Series bulb sizes are:
- BT15
- BT28
- BT37
- BT56
These bulbs are used in stadiums, industrial lighting, and areas where a large surface has to be covered.
C and CA-Series Light Bulbs
Bulbs that have a candle flame-like structure are classified under C-type bulbs. These bulbs are shaped like a candle flame and may have a small tip at the end.
Typical C-series bulb sizes are
- C6
- C7
- C9
- C11
- C15
On the other hand, the CA-series bulbs are similar to the C-type but have a tip that is angularly bent on one side.
Common CA-series bulbs include:
- CA5
- CA7
- CA8
- CA10
- CA11
Both C and CA series bulbs are used in decorative lighting. Especially in fixtures where the light bulb is exposed. You can find these bulbs in bathroom lighting, chandeliers, etc.
E and ED-Series Light Bulbs
E-series bulbs have an elliptical profile. The shape is slightly lengthy and may look similar to B-series. But they are distinguished from the B-series with their egg-shaped head.
Common E-Series bulb sizes include:
- E17
- E18
- E23 -1/2
- E23
- E25
- E27
The ED series is similar to the E-type but has a small dimple at the tip.
Typical ED-series bulb sizes are:
- ED17
- ED18
- ED23
- ED23 -1/2
- ED28
- ED37
Both E and ED series bulbs are widely used in industrial areas, stadium lighting, parking spaces, car showrooms, etc.
F-Series Light Bulbs
These bulbs resemble the shape of a flame. It also has bumps on the body to mimic the flame profile.
F-series bulb sizes include:
- F10
- F15
- F20
These bulbs are typically used in decorative lighting, especially in dark areas to bring ambiance. Mostly red, orange, and blue color lights are used in this series.
G-Series Light Bulbs
G-series bulbs have a globe-like shape. It is exactly like a globe with a perfect spherical shape.
This series has one of the largest size collections. There are around 9 different sizes in this series.
The common G-series bulb sizes are:
- G9
- G11
- G12
- G16
- G16 -1/2
- G19
- G25
- G30
- G40
Due to its perfectly spherical shape, it is widely used in decorative lightings. It can also be found in common household lighting next to A-series bulbs.
T-Series Light Bulbs
The T-type bulbs have a cylindrical shape and are available in different lengths and widths. You can find their lengths varying from 2 feet to 8 feet.
This series houses the largest collection of bulb sizes. Typical sizes include:
- T3
- T4
- T4 -1/2
- T5
- T5 -1/2
- T6
- T6 -1/2
- T7
- T7 -1/2
- T8
- T9
- T10
- T14
- T20
T-series bulbs are used in many applications due to their wide variety of sizes and lengths. You can find household applications, decorative lighting, outdoor lighting, and industrial lighting solutions too.
PS-Series Light Bulbs
These bulbs resemble the pear fruit in shape. It has a spherical top head and a long tubular stem.
Typical PS-series bulb sizes include
- PS25
- PS30
- PS35
- PS40
The small-size bulbs in this category are used in office spaces, commercial buildings, stores, markets, etc. The large-size bulbs in the series are used in radio towers, cellular towers, bridges, and electrical posts.
R-Series Light Bulbs
This is a unique series that houses a reflector material in the bulbs. You can find a flat circular top and this top consists of the reflector. Then it steps down to a tubular stem gradually.
Common R-Series bulb sizes include:
- R12
- R14
- R16
- R20
- R25
- R30
- R40
Flashlights use the same concept as R-series bulbs. The sides of the R-series bulbs are closed and the light only passes through the front glass panel. So, wherever you need focused lighting, you can use these R-series bulbs.
BR, MR, AR, and PAR-Series Light Bulbs
These bulbs are a type of R-series bulbs. All of these have some type of reflecting material placed uniquely.
As for the BR-series, they are not completely oval. They have reflectors in them which provide a wide circular head that is bulged at the top and a gradually reducing tubular stem.
Common bulb sizes in the BR-series are:
- BR25
- BR30
- BR38
- BR40
MR-series bulbs have the same shape as that of the R-series but the reflector material is different. It can spread light from 7-degree to 60-degree angles as per the size.
Common MR-series bulb sizes include:
- MR8
- MR11
- MR16
- MR20
AR series bulbs also have a similar shape to the R-series but the reflector is made up of aluminum. It also has the widest bulb size.
Common AR-series Bulb sizes include
- AR11
- AR70
- AR111
PAR series bulbs have the reflector in a parabolic shape. There are different length variations and width variations in this series.
This PAR series also has a lot of different bulb sizes and can be used in a wide variety of applications.
Typical PAR series bulb sizes include:
- PAR14
- PAR16
- PAR20
- PAR30
- PAR36
- PAR38
- PAR46
- PAR56
- PAR64
All these bulb types are used in areas where there is a need for recessed lighting. It can sit in the ceilings or walls and provide spot lighting or cover a large area like hallways or dining. It can also be used in commercial buildings, offices, marketplaces, etc.
S and ST-Series Light Bulbs
S-type bulbs are small bulbs shaped like A-series bulbs. But they don’t have a large stem and are entirely spherical or have a straight-sided stem.
Typical S-series bulb sizes include
- S6
- S8
- S11
- S14
There is also a slight variation in this series known as the ST-series. The ST series has tapered sides and a rounded top. They are slightly longer than S-series bulbs.
Typical S-series bulb sizes include
- ST18
- ST19
- ST58
- ST64
The S and ST-series bulbs are used in outdoor signs and decorative lights. Due to the small form factor of S-series bulbs, they are usually arranged in a file and used in signboards for decoration and attraction.
We have now familiarised ourselves with the different types of light bulbs according to their shapes and sizes. Now it is crucial to understand why so many bulbs are produced with varieties of shapes and sizes.
Why Light Bulbs are Manufactured With Varieties of Shapes and Sizes?
The use of light bulbs is widespread and it cannot be satisfied with a single type. For instance, you cannot use a S-series bulb to light up an entire outdoor stadium. Also, you cannot use an AR111 bulb to light up a small room. So, different light bulb sizes and shapes satisfy different needs.
The presence of different shapes helps us in three ways:
- The shapes control the angle of beam spread
- Different Shapes aid easy fixing in different scenarios and fixtures
- Shapes provide a decorative feature
If you look at R-series lights and their counterparts (MR, AR, and PAR), they have a large, flat top. This helps to cover a large area and can also be fixed in walls or ceilings easily.
As for the F-series lights, they are purely decorative. You can fix them in chandeliers or wall fixtures for attraction.
In critical areas where large-size light bulbs cannot be used, you can simply use S-series or small T-series bulbs.
Therefore, each bulb’s shape and size serves a unique purpose. It satisfies different scenarios, locations, fixtures, decorations, and any peculiar requirements.
How to Determine the Size of a Light Bulb?
The size of the light bulb is represented by the number adjacent to the shape code of the bulb. The number denotes the diameter of the bulb in ⅛ inches.
For example, the bulb A15 has an Arbitrary shape with a maximum diameter of 15/8 inches. Similarly, you can find the diameter of the bulbs from the number present in the light bulb code.
Do all Types of Light Bulbs have these Shapes and Sizes?
All bulb types, such as LED, CFL, Incandescent, etc. have light bulbs in all the shapes and sizes mentioned above. The shapes and sizes are not influenced by how the light is produced.
Manufacturers may skip one or two shapes for types like the CFL. But you can find incandescent and LED light bulbs in all shapes and sizes.
Since LED bulbs have a longer life, you can find all the different series bulbs in LED. Also, they are available in different sizes as per your requirements.
Conclusion
This comprehensive guide will help you to choose the right type of light bulb for your needs. Before getting a light bulb, understand all the different options available. Especially when you are seeking decorative lighting, you can benefit from the different shapes and sizes available. Also, if you are replacing a bulb, you can get better options if you check out all the varieties.
