Different Bulb Types, Bulb Bases, Bulb Fitting Types & More

There are a wide range of different bulb types on the market. Knowing how to distinguish them is crucial when choosing an appropriate one that is not only compatible with light fixtures for stable functionality but also ensures optimal performance, energy efficiency, and satisfaction in various light settings.

This guide will delve into different bulb types and sizes, shapes, and bases to help you make informed lighting choices as an expert.

6 Common Bulb Types

While there are around 10 different types of bulbs, the most popular types that can be found in common appliances used for homes and offices are: Incandescent, CFL, standard fluorescent, LED, halogen, and HID.

1. Incandescent

What an incandescent bulb is:

The incandescent light bulbs are the most traditional source of electric light and have been in use for over 100 years since the first original invention by Thomas Edison. Compared to other light bulb types, incandescent bulbs are less energy efficient but are usually the least expensive.

How incandescent bulb works:

The bulbs pass the flow of electricity through a filament, which heats a metal filament (typically tungsten) housed inside until the "incandescence" will finally be created and glows. The filament within the glass is filled with an inert gas (commonly nitrogen, argon,  xenon, and krypton).

Pros & Cons:

Understanding some pros and cons of incandescent bulbs is important:

Pros

Cons

Produce soft orange or yellow inviting light that pleases the eyes Versatile lighting thanks to easy dimming Popular for many residential applications Excellent color rendering, sets standard

Not very energy efficient, leading to higher electricity use Pose a high risk of danger due to heat and EMF radiation emission and toxic substance contained (mercury) Relatively short lifespan (about 1,000 hours) Require replacement frequently, results in more waste Sometimes light spectrum (unpleasant harsh, yellowish light)  can affect mood and sleep Be banned in 2023 (by the US Department of Energy) due to energy inefficiency

Incandescent bulbs are familiar and have been the traditional choice for many years, but LEDs are gradually replacing them in most lighting fixtures due to outstanding advantages. In your opinion, incandescent vs LED light: which is better?

2. CFL (Compact Fluorescent Lights)

What a CFL (Compact fluorescent light) bulb is:

CFL (Compact fluorescent light) bulbs are a low-energy alternative to traditional incandescent light bulbs. They are suitable for indoor lighting in residential and commercial spaces. They rely on the reaction of gasses inside their tubes (argon and mercury vapor) to produce light. CFL bulbs require a little time to warm up and get brighter.

How CFL (Compact Fluorescent Light) bulb works:

CFLs consist of a tube filled with a gas mixture (argon and a small amount of mercury vapor). When power is on, an electric current is flown through the tube and excites a mixture of gasses, producing invisible ultraviolet (UV) light. Then the UV light reacts with a phosphor coating inside the tube, generating visible light.

Pros & Cons:

Pros	Cons
Low energy consumption Last longer than incandescent bulbs (typically lasting 6,000 to 15,000 hours) Emit less heat keeps rooms cooler Uses 75% less energy efficiently Low environmental impact	Contain a toxic substance - mercury and requires careful disposal Not perform stably, usually flicker or buzz Take time to reach full brightness UV radiation and EMF radiation emission lead to potentially sensitive people harm Eye strain or headaches due to light spectrum

3. Standard Fluorescent Bulb

What a Standard Fluorescent bulb is:

Fluorescent light bulbs are a specific type of low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to create an invisible ultraviolet light. They are versatile for both indoor and outdoor lighting.

How Standard Fluorescent bulb works:

The gas is excited by the electrical charge running through the inert mercury glass and generates UV radiation. Consequently, this ultraviolet light excites the phosphor covering the inside of the bulb, giving off visible light.

Pros & Cons:

Pros	Cons
Comparable energy efficiency and help lower your energy bills Produce a softer, more natural light Generate very little heat	More expensive than traditional incandescent bulbs Contain hazardous materials like mercury Commonly flickering which can be distracting Tend to produce a harsh, artificial light

4. LED (Light-Emitting Diode)

What a LED (Light-Emitting Diode) bulb is:

LED (Light Emitting Diode) bulbs are highly preferred for their energy efficiency and long lifespan, no heat emission, and are environmentally friendly (contain no mercury). They are also available in various colors and brightness levels. LEDs are the most popular bulbs that are found in different applications. Their directional light is suitable for many intended uses such as task lighting (desk lamps), accent lighting (table lamps), and decorative fixtures.

How LED (Light-Emitting Diode) bulb works:

LEDs are made from semiconductive materials (silicon or selenium) which consist of P-type (positive hole sides or anode) and N-type (negative electron sides or cathode). When the power is on, an electrical current touches the bulb's base, and “jumps” between two electrodes (anode and cathode) in one direction, leading to electrons and holes combination at the P-N junction. And LEDs produce light themselves.

 Pros & Cons:

Pros	Cons
Energy efficient (uses up to 80% less power) Long lifespan (from 20,000 to 50,000 hours), typically much longer than incandescent Low heat emission, reduces fire risk and burns Safe to use Produce a higher-quality of light  Environmentally friendly with no mercury Withstands bumps and vibrations well	Unpleasant harsh, blue-tinged light may disrupt sleep and vision sometimes  High upfront price ($3 - $6 each) compared to incandescent bulbs ($1 - $2) Can increase electromagnetic field exposure Not match incandescent warmth (in case used as an incandescent bulb replacement)

5. Halogen

What a Halogen bulb is:

Halogen is an improved version of incandescent bulbs. They use a tungsten filament sealed in a quartz envelope that is filled with a mixture of halogen gas to produce bright light, which prolongs the life of the filament. Compared to their regular incandescent counterparts, halogen bulbs are more energy efficient, more durable, and moderate quality of light.

Their color temperature is white light, which similar to high-noon daylight, is well suited for under-cabinet lighting, pendant lights, and recessed lighting.

How Halogen bulb works:

The way halogen bulbs work is relatively similar to incandescent counterparts. When an electric current passes through a halogen gas-filled quartz envelope, the chemical reaction produces visible light as well as heat.

Pros & Cons:

Pros	Cons
Energy-efficient and cost-effective option Emit a very bright and intense light Small in size and compact Relatively long-lasting compared to traditional incandescent bulbs Bright and intense light Energy-efficient	Produce a large amount of heat during use More expensive than other bulb types Risk of fire hazard  Not as environmentally friendly as LED bulbs (contain small amounts of mercury)

6. HID (High-Intensity Discharge)

What a HID (high-intensity discharge) bulb is:

HID stands for high-intensity discharge indicating bulbs using gas-discharge light electrical technology. HID bulbs produce powerful, large efficient illumination and play an important role in outdoor lighting (road lighting, sports stadiums, parking lots) and indoor lighting (gardening) as well as automotive lighting.

How HID (high-intensity discharge) bulb works:

These lights produce illumination by harnessing the power of electrical arcs between electrodes (usually made from tungsten) housed in arc tubes. The arc tubes are commonly made from quartz, filled with an amalgam of gas and metal salts. The arc then heats the metal salts, and ionized gas (also known as “plasma”) contained inside the bulb.

Pros & Cons:

Pros	Cons
Lower initial cost Offering bright white or blue  lumens Energy efficiency	Release considerable amounts of ultraviolet (UV) radiation Need additional parts such as a ballast to ensure stable performance Take time to warm up Containing toxic material internally

7. Other types of bulbs

Besides 6 most common bulb types above, we may find these different types of bulbs in some lighting fixtures:

• Sodium Vapor Bulb: These bulbs are famous for sodium vapor light bulbs which are high-efficiency lighting, typically used in street lights and industrial applications. By ionizing sodium vapor housed inside, these bulbs can emit bright orange-yellow light. They are highly efficient. Sodium vapor light bulbs are long-lasting. They are relatively inexpensive to operate.
• Mercury Vapor Bulb: These bulbs are high-intensity discharge bulbs that use mercury vapor to glow. Their bright illumination looks the same as natural sunlight. Mercury vapor bulbs are usually used in parking lots, street lamps, and industrial lighting.
• Smart Light Bulbs: Connected to home Wi-Fi, this type of bulb provides greater and easier control for owners such as setting the lights to turn on and off schedule, changing colors, and dimming through a smartphone or voice assistant. It’s a way more convenient lighting solution and helps improve your home security.
• Spotlight Light Bulbs: Spotlight light bulbs are an ideal option for track lighting and recessed lighting due to their intense and concentrated beams of light. They are used to attract attention to accent architecture, artwork, or exhibition collections.
• Reflector Light Bulbs: As their name suggests, reflector light bulbs use a reflector to direct bright and focused beams of light to desired areas. They are commonly made from glass, metal, or plastic and cost relatively more than others.

Ultimately, in terms of popularity,  energy efficiency, longevity, lighting output, and intended usage, LEDs have claimed the crown as the best combination of these features.

Related articles:

• 4 Safest Light Bulbs to Use - A Comprehensive Guide in Lighting
• Are LED Lights Safe? Understand the Risks and Myths about LED

11 Types Of Bulb Shapes

Light bulb types chart is also classified according to different bulb shapes, but the more common shapes include:

Type	Shape	Diameter (in inches)
A (Arbitrary/Standard Household)	A-line or pearl-like shape	From 1.85 to 2.875
B (Bulged)	Bullet or flame-like	From 1 to 13.125
BR (Bulged Reflector)	Parabolic arch	From 3.125 to 5
C (Candle or Conical)	Flame-like with a wider middle and a thin and elongated	From 0.5 to 1.875
PAR (Parabolic Aluminized Reflector)	Parabolic	From 1.75 to 8
MR (Multifaceted Reflector)	A flat top and a rounded bowl bottom	From 1 to 5
E (Edison)	Globe	From 1.75 to 4.625
R (Reflector)	Built-in surface with flat top	From 1.5 to 5
T (Tubular)	Tubular elongated	From 0.4 to 0.8

 

1. Type A

Main feature: The Versatile Choice

Characterized by standard A-line shape, type A bulbs are familiar and widely available, commonly used for all standard lighting of both residential and commercial applications. They produce omnidirectional illumination throughout a space and maintain reliable and consistent performance. They are well-suited for many general lighting (ambiance light in living rooms, bedrooms, dining rooms, and hallways) and task lighting (desk lamps or reading lights) purposes.

Although A-line-shaped bulbs come in several sizes, the most popular options and standard sizes compatible with most lighting fixtures (such as table lamps, pendant lights, floor lamps, and ceiling fixtures) are A19, A21, and A60.

A19, A21, and A60 bulbs fit with E26 and E27 screws, which are the standard base type and size.

2. Type B

Main feature: Decorative and Dim

Specific shapes of type B bulbs are bullet or flame-like shapes that start narrow at the bottom, curve outward at the middle and a point on top. Others bulge at the base, and get thinner as they reach the top.

Type B bulbs emit a soft and warm glow, adding elegance and charm to spaces, creating a relaxation and intimacy mood for dining rooms, bedrooms, and living rooms. Therefore, type B bulbs are often used in wall sconces, pendant lights, chandeliers, and small lamps as decorative lighting fixtures to enhance the overall aesthetic of a space.

B22 bulbs are also known as bayonet cap light bulbs, the popular B type on the market, relatively easy to find not only in LED versions but also compatible with dimmers. Besides, B10 bulbs are also a relatively popular choice for household and commercial lighting.

3. Type BR

Main feature: Wide-Angle Lighting

BR (Bulged Reflector) bulbs have a narrow bottom, but a raised top with rounded edges. BR bulbs create a soft wide-angle illumination, an ideal lighting solution for large areas where ample and evenly distributed light is needed such as kitchens, living rooms, and offices.

BR30 bulbs (reflector-style bulbs with a wide flood-like beam shape), one of the most common types that can be found in household lighting, are ideal for general room illumination. In addition, BR40 is often applicable for floodlights, BR38 is used for IR heat lamps while BR20 bulbs dominate top-selling products due to low wattage, high lumens, and a very wide flood beam angle.

4. Type C

Main feature: Decorative

C indicates candle or conical, or also candelabra, illustrating the shape of a bulb that looks like a flame with a wider middle and a thin and elongated (sometimes more rounded) point on top.

Type C bulbs enhance the aesthetic appeal of a space thanks to soft and warm illumination distribution. Moreover, reminiscent of the flame of a candle from C bulbs is prized for decorative appeal, especially used in electric candles, night lights, and chandeliers.

While C7 and C9 bulbs are widely used for Christmas lights or seamlessly fit with traditional chandeliers or with modern fixtures, C15 is an energy-efficient option and fits most light sockets.

5. Type PAR

Main feature: Precision Lighting

PAR (Parabolic Aluminized Reflector) bulbs are recognized for their parabolic shape (flat tops and a bowl-shaped stem) accompanied by a built-in reflector to direct light. This feature allows them to emit a broad directional light, drawing attention to focal points or architectural details, and contributing to the overall aesthetic appeal of a room.

Common PAR bulbs for residential lighting are PAR20, PAR30, and PAR38 (the most popular). PAR 30 and PAR 38 bulbs cooperated with LED, and are preferred for spotlighting inside and outside where a larger coverage area is needed.

6. Type MR

Main feature: Small but Powerful

MR (Multifaceted Reflector) bulbs are famous for their small size and powerful directional lighting capability, featuring a flat top and a rounded bowl bottom.

Their precision lighting production ability makes them ideal for highlighting objects and creating visual interest. They are commonly used for residential and commercial light purposes (such as projectors, retail displays, and track lighting) or areas where a dramatic lighting effect is desired (such as art galleries, and architectural features).

In the MR group, MR11 and MR16 are two popular types, most likely seen in indoor applications thanks to their flair style and highlighting capabilities.

7. Type G

Main feature: Globe Lighting

G (Globe) bulbs are prized for their functional versatility and aesthetic appeal, featuring large, spherical shapes. Their soft and diffused illumination set the mood of a warm and welcoming atmosphere, elevating the aesthetic and functionality. They are commonly applicable in pendant fixtures, vanity lights, and modern decor fixtures.

G30 bulbs commonly found in lighting fixtures for bathrooms, dining rooms. or vintage-styles lamps.

8. Type E

Similar to the shape of type A, but type E (Ellipsoidal) bulbs have a more oval shape instead of a rounded appearance. Type E bulbs feature a screw-in base. In type E shape group, E26, E14 and E27 bulbs are the most popular on the market and can be instantly recognized by looking at the bottom.

9. Type R

As the name suggests, R type (Reflector) bulbs are characterized as flat top and a built-in surface shape. These bulbs produce reflective layer directed illumination. These bulbs are commonly applicable in floodlights, spotlights and commercial lighting fixtures. You may also encounter type R bulbs ranging in size from R12 to R40.

10. Type T

Featured by a tubular elongated shape, T bulbs are used in longer (or taller) designs with smaller width appliances. T bulbs are available in different lengths and wattages based on the size and style needed for a given fixture.

The T-type light bulb bases are screw-in (E26 and E27 medium screw bases, E12 candelabra bases, E17 bases and BA15D bayonet bases) or pin connectors (G13 bi-pin base). And these bulbs are commonly coordinated with fluorescent technologies.

For instance, you are likely to see the T8 (8/8 inch) diameter or T12 (12/8 inch) diameter in a laundry room, kitchen, or garage. They are often associated with fluorescent and LED bulbs.

11. Type BT

The BT-type bulbs are relatively similar to B-type shapes, but BT bulbs have a wider middle part and the end tends to be blunted and less round, which makes them look like a bulged chimney instead of a candle flame as type B. They are frequently associated with halogen, LED and incandescent bulbs.

In the BT group, BT28, BT37, and BT56 bulbs are often seen in car dealerships, canopy lighting, sports arenas, and industrial applications.

12. Other types

These less popular shape types that you may not come across as regular as other bulbs.

• Type CP: This is a C-type bulb which uses “panels" to distribute light in a more fractured manner but its appearance looks like more of an A-type shape.
• Type ER: This type has the same length as the BR-type shape, but has less width to manage, and is used as an effective alternative BR-type bulb.
• Type F: Another variation of the “candlelight” design, F-type bulbs have a more natural look due to a more bulbous base and a rounded tip. They are not only found in chandeliers and candelabras but also work in a wide range of light fixtures.
• Type HK: This type uses a more angular definition to replicate the visual aesthetic of a candle's flame. The screw-in base size is typically smaller than a standard design.
• Type K: The K-type light bulb is a type of incandescent bulb that emits whiter and purer while reducing the yellowish color lighting output.
• Type MB: MB-type light bulbs are usually found in incandescent-style lamps that use halogen gas.
• Type P: The circular design of this type is relatively similar to the G bulb group, but the key difference is the lack of an extension between the base and the outer shape.
• Type PS: PS bulbs are pear-shaped but more extended and skinnier stems while maintaining the traditional shape at the end. They are limited in terms of size, just have two versions: PS25 and PS35, and are applicable for home-based installations.
• Type S: This type is associated with recessed lighting applications to provide a compact option with minimal-width lighting. S type also works well with low-wattage applications.

Browse our wide range of different bulb shapes, the most common bulb shape include:

• Classic A-shaped bulbs (A19 and A21) used in a wide range of fixtures, from table lamps to ceiling lights
• E type bulbs (the most common type Edison screw base)
• Reflector-style BR30 usually found in recessed and track lighting
• G4 small bi-pin bulb commonly used in decorative fixtures and task lighting
• T8 coordinated with linear fluorescent technology with T8 ballast

6 Types of Bulb Bases

Bulb base type is also a factor used to differentiate types of bulbs. Choosing an accurate base to ensure a well-suited fitting screw and perform stability functionality.

There are 6 main different bulb fittings, including:

1. Screw bases

The Edison screw (ES) base, named after inventor Thomas Edison, is the most common design used with electric light bulbs. The bulbs have metal bases (caps) that are threaded in the right direction and screwed into matching threaded sockets (lamp holders). Edison-Screw Base. Some common screw base names are:

• E39 - Mogul base
• E26 - Medium base
• E17 - Intermediate base
• E12 - Candelabra base
• E11 - Mini Candelabra base
• E10 - Miniature base
• E5.5 - Midget base

2. Twist and Lock bases

These bulbs have 2 pins protruding from the bottom to insert into the corresponding holes in a socket and twist to lock into light sockets instead of screwing like Edison screws with a twist. GU10 and GU24 are two popular types of twist and lock bases.

3. BI pin bases

Bi-pin bases are recognized by their two pins that stick out of the base, which are used to insert into matching sockets. Bi-pin bases are often widely used for fluorescent, halogen, a few types of HID light bulbs and LED bulbs.A bi-pin bulb base is commonly seen in recessed fixtures and office lighting or smaller, low-voltage lighting applications (G4 base).

The common types of bi-pin bases available are GU5.3 and GZ4 (for MR bulbs within low-voltage AC/DC systems), and GU10 (for 120-volt systems). You probably encounter G, GU4, GY6.35, GU8, GY8, G9, and G12.

4. Fluorescent pin bases

Different kinds of fluorescent bulb bases are diversified by the technology they coordinate. For instance,  miniature bi-pin bases are regularly found in linear preheat and rapid-start fluorescent light bulbs while most LED and instant-start fluorescent lightings use single-pin bases. Circline lighting fixtures use 4-pin bases.

The different types of fluorescent bulb bases include:

• Mini bi-pin: Used in linear fluorescent lighting
• Recessed D.C:  Not very common, used in some  linear fluorescents bulbs (R17d)
• G10Q (4-pin): Used for G10 quad pin (T9, T10 and T29)
• Medium bi-pin: Used in a variety of linear fluorescent bulbs (T8 and T10)
• Single-pin: Not very common, used in some  linear fluorescents bulbs (Fa8)
• 2GX13 and Axial are rarely seen

5. Specialty and custom base

Following some different types of specialty and custom bases you may encounter:

• Festoon base: This base's appearance looks like a dome or torpedo. These bases are commonly used for car map lights and other appliance bulbs.The 12 and 24-volt variations are the two most common festoon bulbs.
• Medium-side Prong Base: These bulbs have two projections: medium-side prong bases or prongs like GU bulbs that hold them in the socket. But the key point that differentiates them from GU bases is the one-side prongs.
• Wedge Base: The two pins of a wedge base consist of wires twisted and bent to the base's ends where they contact the socket at the base's ends.
• Bayonet Base: A bayonet base has single as well as double-contact projections on the sides that retract while inserted into a socket. For example, the BA15d base is a double-contact bayonet base while the BA15s is a single-contact one.
• Single-contact Base: A single-contact base has a single pin, mostly seen in instant-start and rapid-start tube light fixtures.
• Cable Bases: Feature a cable power direct wiring connection into the power source. Common applications are mechanical switches and valves.

6. Compact fluorescent plug-in base

This type base is classified into two types: either 2 pins or 4 pins. The 2-pin lamp base is designed for preheating magnetic operation and has an internal starter  for use with magnetic ballasts while the 4-pin bases are designed for electronic ballast operation, are dimmable and.for use with electronic ballasts. Some of the most seen plug-in bases are G23, GX23-2, G24Q-2, and GX24Q-3.

Most popular types of base on the market are:

• Regular medium size screw base found in most North American fixtures: E26 or E27
• Small size screw base for type C bulbs used in chandeliers and decorative lightings: E12
• Intermediate size screw base: E17
• Flat, two-pin base found in halogen and LED downlights: G4 or GU10
• Twist and lock base used in energy-efficient fixtures: GU24

Sizes Of Light Bulbs

It seems to be a simple and “anyone can do” task to identify light bulb base sizes because the code marked on the bulbs has already indicated the types, shapes as well as sizes.

How to read and understand the bulb code: The code number of a bulb consists of a letter or letters followed by a number. The letter reveals its type bulb while the number shows the bulb diameter in eighths of an inch.

Bulb diameter = The number in eighths of an inch

For example: A19 - the most popular household bulb. The bulb shape is "A" type (code A) and the base diameter would be 19/8ths inches.

Practice more by looking at popular sizes of light bulbs follow:

• Edison Screw (E26) base size measures 26mm in diameter
• Candelabra Screw (E12) base size measures 12mm in diameter
• GU10  base size measures 10mm in diameter
• G9 base size measure 9mm in diameter
• T8 base size 1mm in diameter

Guides To Choose The Best Light Bulb

1. Watts

With the same lumens produced, the more wattage a bulb requires, the more power consumption is needed. Likewise, the brighter illumination, the higher wattage the bulb consumes. Remember to consider the maximum wattage that the bulbs can sustain.

2. Lumens

To explain simply, lumens indicate the brightness level produced. Similar to watts, the higher the lumen, the brighter the light. Recommended lumens for most rooms is 20 lumens per square foot. Depending on the darkness of your room, you can choose bulbs that have additional 10 lumens per square foot.

To choose appropriate bulbs that have lumens that suit your lighting needs, it’s imperative to know the square footage of the room or area and determine the number of light fixtures used to light your space.

3. Color temperatures

Color temperature measured in Kelvins (K), refers to the appearance of light and the desired lighting effects created by the bulbs.

• Warm white light (2700K to 3500K) emits yellowish or reddish illumination, setting the mood of a cozy and relaxation, often used in living rooms, bedrooms, and restaurants.
• Neutral light (3500K to 4000K) provides a balanced, natural brightness, suit focused task lighting such as office, work setting and basement.
• Cool white (4000K to 5000k) creates bluish or whitish lighting, provides a sense of alertness and focus, making it suitable for offices, workspaces, and kitchens.
• Daylight (range from 5000K to 6500K) replicates natural sunlight and offers a clean and neutral feel, ideal for tasks requiring good color accuracy.

Based on your needs, find out what color temperature is the best.

4. Shapes

Besides different lighting effects influenced by shape, the right shape is also used as a decoration to contribute to the home's style. Candles or candle-angular-shaped light bulbs are perfect for traditional chandeliers while globe-shaped light bulbs are more suitable for modern pendant lights.

5. Bases

To ensure a secure fit into the fixture and prevent electrical hazards such as short circuits, it’s crucial to understand the different light bulb bases. The specific code or label marked on the bulb bases shows the base type. Inspect your light fixture to ensure bulb base type and size are well-paired. The universally popular bases are screwed-in "Edison's" bases.

How do you match bulb bases to fixtures? Follow these steps:

• Check your light fixture or the base of your existing bulb for the base code to determine the base size that fits your existing fixture.
• Choose the right bulb type base based on the type, base, and size. Remember to consider these factors.

6. Sizes

Bulb size refers to the physical dimensions of the bulb. The size is typically indicated by a number and letter combination that is marked on the bulb. The number indicates the bulb diameter is 1/8th of an inch, while the letter refers to the bulb's shape. Picking the right bulb size to ensure proper fit compatibility.

7. Replacement

Switching to LEDs from traditional incandescent, compact fluorescent (CFL) bulbs can reduce heat emission, and lower your electric bills ensuring good lighting performance. For example:

• Replacing 50-watt low voltage MR16 bulbs (normally cooperated with track lighting) to 7 watt MR 16 LED bulbs
• Switching a 60-watt incandescent or a 13-watt CFL bulb to a 10-watt LED bulb
• Converting a small 50-watt R20 flood bulb (used in recess or landscape lighting,) to an 8-watt LED R20 bulb

8. Energy efficiency

Energy efficiency is also an important factor you should consider when choosing bulbs for lighting fixtures that can lower your electric bills.  LED bulbs are famous for their significant energy efficiency, becoming more popular and gradually taking over other different bulb types. LEDs are beneficial for long-term investment despite high upfront costs. 

9. Lifespan

Choosing a long lifespan can reduce the cost of replacing an old malfunctioning one. The longer the life span, the lower the depreciation expense. The most long-lasting bulb is LED.

Conclusion

Knowing how to combine and analyze factors including different bulb types and shapes, different bulb bases and sizes to identify the accurate lighting bulb to achieve both desired lighting needs and stable functionality performance.