An Ultimate Guide to Different Bulb Shapes and Sizes - CLAXY
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An Ultimate Guide to Different Bulb Shapes and Sizes

Light bulbs come in a myriad of shapes and sizes, which can be confusing for everyone. This guide is gonna help you figure out the difference among bulb shapes and let you know which shape of bulb is perfect for your light fixtures.

The names of light bulb shape are usually denoted with a letter, depicting the shape, and a number, indicating the size. In the US, the size of a lamp bulb generally refers to the width of the bulb at its widest point designated in eighths of an inch. For example, an A19 is an A shape bulb and is 2.375 inches in diameter (19 divided by 8). If you are not quite familiar with the size of a light bulb when you need to buy a new one, you should take your old bulb to the local hardware store and make sure that you won’t purchase a wrong one.

Now we have a graphic below to show you the actual appearance of different bulb shapes. Generally there are 17 categories of bulb shapes in total. Let’s get down to business and introduce to you all the light bulb shapes.

light bulb shapes

1.A Series Bulbs

A group stands for arbitrary and the arbitrary bulbs are also called the A-type lamp which is denoted with an A. The A-shape light bulb is the most common light bulb for general home lighting applications such as desk lamps, ceiling fans, and closets. Type A bulb is available in both halogen and LED bulbs.

Typical sizes: A15, A17, A19, A21 and A23.

2.B Series Bulbs

B Series Bulbs are called bulged bulbs (B). Type B bulb usually serves as decorative lighting. They look somewhat like an elongated oval and they are well suited for chandeliers and other decorative lights.

Typical sizes: B8, B10, B11 and B13.

3.BT Series Bulbs

The blown tubular (BT) light bulb is a T light bulb that has had the glass blown in the middle so that it appears to have a bubble in the middle of the tube. BT halogen light bulbs can replace incandescent light bulbs. High-intensity discharge light bulbs come in BT28, BT37, and BT56. They are used in sports arenas, car dealerships, canopy lighting, and industrial applications.

Typical sizes: BT15, BT28, BT37 and BT56.

4.C Series Bulbs

Candle bulbs (C) are best suited for light fixtures that emulate candelabras and can be seen in decorative lights in restaurants, bathrooms, and hotels. Candle bulbs are slightly rounded with a small tip on the end. They are decorative bulbs for chandeliers and holiday lights.

Typical sizes: C6, C7, C9, C11 and C15.

5.CA Series Bulbs

Candle angular bulbs (CA) offer a unique twist on the traditional candle bulbs with a bent tip. You can find them in exposed chandeliers and other decorative light strands.

Typical sizes: CA5, CA7, CA8, CA10 and CA11.

There are other three types of candle-style bulbs including candle twisted bulbs, hexagonal candle bulbs and extended candle bulbs.

1)Candle twisted bulbs (CW) with a blunt tip are made to look like a candle flame with spiral patterns on the bulbs. These bulbs are good for chandeliers and other decorative home lighting applications.

2)Hexagonal candle bulbs (HX) are in the shape of diamond and mainly serve as decorative light bulbs. They bring extra texture and exude lovely glow to any room in your home.

3)Extended candle bulbs are referred to as the elongated torpedo shape with a blunt tip. You can find them in chandeliers, night lights and decorative light strands.

6.E Series Bulbs

Ellipsoidal bulbs (E) look like elongated ovals that are a bit bulged in the middle. They come in a myriad of variations which can be shorter, fatter as well as ones that are much longer and skinnier. They are perfect bulbs for car dealerships, industrial lighting, sports arenas, and parking garages.

Typical sizes: E17, E18, E23½, E23, E25 and E37 .

7.ED Series Bulbs

Ellipsoidal dimple bulbs (ED) look alike to ellipsoidal bulbs but they are generally a bit larger and sometimes longer than ellipsoidal bulbs. They do have a dimple on the end of them and their base is usually different. They are great for car dealerships, industrial lighting, sports arenas, and parking garages.

Typical sizes: ED17, ED18, ED23½, ED23, ED28 and ED37 .

8.F Series Bulbs

Since the flambeau bulbs (F) take the shape of a flickering flame, it is easy to remember that it is denoted with F. They are not good for bad weather, high humidity, or extreme temperature fluctuations. However they are great for adding a little drama to a lamp or chandelier in bathrooms and restaurants.

Typical sizes: F10, F15 and F20.

9.G Series Bulbs

These globe bulbs (G) have a full, round shape and are available in various sizes. They can make for a very attractive appearance throughout the home, such as foyer lights, kitchen lights, chandeliers, and ornamental fixtures. The most common type is the large G30 bulb, which is used in bathrooms and makeup vanities. Homeowners use them on both ornamental lighting and floodlights.

Typical sizes: G9, G11, G12, G16, G16½, G19, G25, G30 and G40.

10.GA Series Bulbs

These decorator bulbs (GA) take an interesting shape of a scallop. They usually act as decorative lighting and will definitely introduce a playful touch to any room in your home.

11.K Series Bulbs

Kryption bulbs (K)’s appearance resembles scallops and injects a touch of whimsy to your home. These light bulbs are generally used in decorative applications.

12.P Series Bulbs

Pear light bulbs (P) look similar to A series bulbs, except they have a more rounded body, which causes the bulb to look like a pear. Typical sizes are PS30 and PS40. You can see PS30 light bulbs in office buildings and retail stores, whereas PS40 light bulbs are used in radio towers, cellular towers, bridge power lines, and high tension wires.

There are other three types of pear-styled bulbs including pear-straight bulbs, ogive bulbs and crystalline pear bulbs.

1)Pear-straight Bulbs

Pear-straight bulbs (PS) are rounded on the top and gradually become narrow on the lower part. You can see them in office buildings and retail stores, radio towers, cellular towers, bridge power lines, and high tension wires.

2)Ogive Bulbs

Ogive Bulbs (PC) take the shape of olives and look extremely bulky in the middle. Their adorable look brings texture and depth to any space in the house.

3)Crystalline Pear Bulbs

Crystalline pear bulbs have a hexagonal body that adds a bit of character to any space.

13.PAR Series Bulbs

Sealed Beam light bulbs (PAR) are reflector light bulbs that have an aluminized reflector in a parabola shape. PAR light bulbs can be used outdoors unprotected because their hard glass shell can withstand adverse weather. You can also find PAR light bulbs in downlighting applications in recessed cans and track lighting in residential, retail, museums, and art gallery applications. Typical sizes include PAR16, PAR20, PAR30, PAR30 long neck, and PAR38. The PAR30 long neck was introduced to replace incandescent BR30 light bulbs in recessed cans in which standard PAR30 light bulbs did not fit.

Typical sizes: PAR14, PAR16, PAR20, PAR30, PAR36, PAR38, PAR46, PAR56 and PAR64.

14.R Series Bulbs

Blown Reflector (R) bulbs are perfect for track lighting as well as recessed lighting. Due to their shape, they do a great job in helping direct the light forward so that it is not lost through the sides of the bulb. This will allow homeowners and business owners to use these lights to have a little more impact or effect in their home or store. They’re great for drawing attention to something that you want to show others.

Typical sizes: R12, R14, R16, R20, R25, R30, and R40.

15.BR Series Bulbs

BR stands for bulged reflector. Traditionally, the inside surface of a BR bulb is covered in reflector material to gather and cast a wide beam of light away from the bulb. They’re a bit longer than PAR bulbs and tend to protrude from light housings but are used in similar applications, such as track lights, recessed lights, display lights, or can lights.

Typical sizes: BR25, BR30, BR38 and BR40.

There are other two types of reflector bulbs including ellipsoidal reflector and double reflector.

1)Ellipsoidal Reflector (ER) bulbs are uniquely designed to project light further than other reflector bulbs. They are a great option for use in recessed lights as they lose less light in baffles than standard BR- or R-type bulbs. The most common size is ER30. You can see them in downlighting in recessed cans for residential, hotel, and office applications.

2)Double Reflector (NR) bulbs are a perfect option for use in recessed lights. They are popular in homes, hotels and office buildings.

16.S Series Bulbs

You can usually find s series bulb in outdoor signs. You will see type S light bulb at theaters, casinos, restaurants, and even hotels.

Typical sizes: S6, S11, and S14. S6, S8, S11, S14, and ST18

17.T Series Bulbs

Tubular (T) light bulbs take the shape of a cylindrical tube. These bulbs come in a variety of lengths and widths. You can see Incandescent T6 light bulbs in exit and stairway signs and picture lights. Linear fluorescent T12, T10, T8, and T5 light bulbs come in a variety of lengths, ranging from 2-8 feet. You can find these light bulbs in fluorescent troffers and for general lighting in offices, retail outlets, hospitals, and parking garages. High-intensity discharge light bulbs also come in T shapes, including T9 and T15. These light bulbs are in sports arenas, billboard signage, and industrial applications.

Typical sizes: T3, T4, T4½, T5, T5½, T6, T6½, T7, T7½, T8, T9, T10, T12, T14, T15, and T20.