A Complete Guide on LED Light Bulbs

LED Light Bulbs

The LED light bulbs are booming in the lighting market now. The prime replacement for the incandescent light bulb is the higher-efficiency compact fluorescent or CFL. The CFL, though, has its problems, primarily the inclusion of toxic mercury in the design and a strange, sometimes unpleasant color that even gives some people headaches.

LED or light-emitting diode, have been around for many years, they light up digital clocks, Christmas lights, flashlights and traffic signals, and they tell you when you’ve got a new voicemail message on your cell phone. But as far as household lighting goes, LEDs have not really taken off yet. Certain drawbacks have kept companies from manufacturing them in standard, replacement-size light bulb form.

In the last few years, though, these LED replacement bulbs, the kind you just screw into a lamp like you do an incandescent bulb, have become much more common, which is to say a fair number of businesses and a handful of households are using them.

Basics of LED Light Bulbs:

An LED is what’s called a “solid-state lighting” technology, or SSL. Basically, instead of emitting light from a vacuum (as in an incandescent bulb) or a gas (as in a CFL), an SSL emits light from a piece of solid matter. In the case of a traditional LED, that piece of matter is a semiconductor.

Stated very simply, an LED produces light when electrons move around within its semiconductor structure. A semiconductor is made of a positively charged and a negatively charged component. The positive layer has “holes” – openings for electrons; the negative layer has free electrons floating around in it. When an electric charge strikes the semiconductor, it activates the flow of electrons from the negative to the positive layer. Those excited electrons emit light as they flow into the positively charged holes.

The problem with LEDs as primary home lighting is that while they emit a lot of light, the structure of an LED causes some of that light to get trapped inside. So an LED bulb has traditionally been dimmer than an incandescent bulb, and most people want their lamps and ceiling fixtures to be pretty bright.

Recently, though, LEDs bulbs have brightened up. You can now find LED replacement bulbs that emit light equivalent to a 60-watt incandescent light bulb, which makes them a viable technology for basic lighting needs at home. And in some ways, they’re much more than viable: An LED replacement light bulb emits 60-watt equivalent light using 7.5 watts of power. 

Also read: What are the Different Types of Lighting Systems?

Why Switch to LED Light Bulbs?


While you won’t find LEDs in too many household lighting fixtures these days, there are a couple of good reasons to want them there in greater numbers. First, there’s the reduced energy use. The LED method of producing light loses far less energy to heat than do other lighting technologies. It’s dramatically more efficient than the vacuum/filament method used in incandescent bulbs, sometimes around 85 percent more efficient, and it’s even about 5 percent more efficient than the CFL’s plasma-tube approach.

A single light fixture stocked with a 60-watt incandescent bulb consumes about 525 kWh of electricity in a year; put a LED bulb in that light fixture, and the annual energy use is more like 65 kWh. The annual CO2 reduction is in the hundreds of pounds for a single lamp.

But energy-efficiency is just part of the story. The other part is time-efficiency: You could go 20 years without having to change an LED light bulb. Solid-state lights like LEDs are more stable light sources than incandescent or fluorescent bulbs, and the difference is startling: A typical incandescent bulb lasts about 750 hours; Some LED bulbs last up to 50,000 hours.

Because of that time benefit, things get a bit more muddled when you get into the cost issue. A 60-watt LED replacement bulb runs in the area of $100, and even the lower-output versions, used for things like spotlighting, will cost between $40 and $80. That’s compared to a $1 incandescent and a $2 fluorescent bulb.

The reality is, even at $100 for a single bulb, LEDs will end up saving money in the long run because you only need one every decade or two and you spend less money on home lighting, which can account for about 7 percent of your electric bill. But the upfront cost is still pretty prohibitive. Lots of people simply can’t spend a thousand dollars for 10 light bulbs. LEDs can produce the same soft, white light as a regular bulb. So the price is the only problem with LED light bulbs right now. But that could change pretty soon.

When shopping for light bulbs, you can sidestep the bans and continue using incandescent bulbs, despite their limited lifespan, so that you don’t have to give up the familiar glow you’re used to. Some have taken the first step to use energy-efficient lighting use compact fluorescent light (CFL) bulbs.

Compared to incandescent bulbs, CFL bulbs seemed like a great upgrade. However, the reduced power consumption and heat output came with two drawbacks. Many compact fluorescent light bulbs don’t achieve full brightness immediately or work well with dimmers. This has made it difficult for some to replace their incandescent lights until they could upgrade without these compromises; this is where LED lighting comes into play. When compared to incandescent and CFL bulbs, LEDs generate the same amount of light while using a fraction of the energy. LED bulbs turn on instantly to full brightness and last far longer.

Buying the right LED bulb is more than just adding one to your cart or picking one up off of a shelf.  Aspects you need to consider as you look for an LED bulb:

  • Shape
  • Base type
  • Brightness
  • Color Temperature
  • Features

LED Bulb Shapes:

metal halide light

One of the most important things to know if you’re looking to buy a LED light bulb is the shape. When it comes to light bulbs, bulb shape designations have two parts made up of letters and a number. The letters describe the bulb type while the number is an indication of the actual size where a higher number represents a larger bulb size. These numbers are used to reflect the diameter of the bulb in multiples of 1/8th of an inch. LED bulbs can be broken down into four primary categories of shapes: A-shape, reflector, decorative, and speciality.


A-shape LED bulbs are the most common shape available and are commonly referred to as standard shape LED bulbs. An A19 bulb has a maximum diameter of 2 3/8th inches (19/8 = 2 3/8). This shape is commonly used for LED bulbs that replace incandescent bulbs up to 75 Watts. LED replacements for 100 Watts or higher typically have an A21 shape. You may also find some LED bulbs which use the smaller A15 shape.

Also read: The Complete Guide to Photography Lighting


These bulbs are most commonly referred to as flood or spot light bulbs due to their reflective coating, which is used to create a wide or narrow beam angle. Reflector LED bulbs have the letter R in their bulb shape designation. You’ll find the most common types listed below:

1. MR (Mirrored Reflector)

Designed to focus lighting into a single focal point, MR bulbs are commonly used in track lighting, recessed lighting, and landscape lighting to replace halogen bulbs.

2. R (Reflector) and BR (Bulged Reflector)

Both R and BR bulbs are directional, focusing light outward. R bulbs have a mirror-like coating inside the housing. BR bulbs are similar but have an additional mirror in the neck, creating a “bulge” just before the socket base. These bulbs are used in recessed and track lighting and are a popular choice for wall washing or grazing.

3. PAR (Parabolic Aluminized Reflector)

PAR lamps have a flat lens and are available in several shapes including, PAR16, PAR20, PAR30, PAR36, and PAR38. These lamps are suitable for a wide variety of applications including track lighting, recessed lighting, and outdoor floodlighting.

4. AR (Aluminum-facetted Reflector)

Replacing halogen bulbs, AR lamps are generally used for low voltage applications from 12 to 24 Volts, but may also come in 120V options. These bulbs are used for retail displays and architectural lighting.

LED Decorative Bulbs:

Smaller than A-shaped bulbs, LED decorative bulbs are commonly found in wall sconces, chandeliers, and other decorative fixtures. These bulbs are designed to add to the look of your décor and provide ambient light.

Chandeliers –


Featuring a shape similar to a candle, chandelier bulbs are a popular choice for a wide range of decorative lighting. Chandelier bulbs are available in these shapes:

  • B (Bullet) – Also referred to as Torpedo bulbs.
  • C (Candle or Conical) – Conical bulbs are most commonly used for night lights and Christmas replacement bulbs.
  • CA (Candle Angular) – Designed to mimic the look of a flame, CA decorative bulbs are often referred to as Flame Tip (F) or Bent Tip bulbs.
  • LED Filament –  Available in both bullet and candle angular shapes, these bulbs use LED filaments to mimic the look of antique lighting.

Globe – LED globes have a spherical design that is easy to recognize. These bulbs range in size from a 1.5-inch diameter up to a 5-inch diameter. Aside from vanity lights, LED globes are commonly used in wall sconces, light stringers, and other decorative fixtures. If you desire a more vintage look, choose LED globes with LED filaments.

LED Filament Bulbs:

LED filament bulbs produce a warm glow while giving your fixture a classic look. To recreate the look of incandescent vintage lighting, the LED diodes of these bulbs are designed into a thin bar. The LED filaments last far longer than traditional filaments, but cannot fully replicate the look of wire filaments. If you desire that delicate look, choose traditional vintage bulbs instead. Aside from the chandelier and globes mentioned earlier, LED filament bulbs are available in these popular shapes:

  • Edison –  Reproductions of Thomas Edison’s first light bulb, these popular LED bulbs are used in pendants, wall sconces, and lamps.
  • Victorian – Popular for lamps, sconces, and other decorative fixtures, Victorian bulbs have an A-lamp shape.
  • S14 – Vintage S14 bulbs have vertical or horizontal filaments and are typically used for patio string lights.
  • LED Silver Bowl –  Featuring a chrome finish on the top half of the bulbs, LED silver bowl bulbs to reduce glare by redirecting light back into the fixture. These bulbs are popular picks for pendant lights.
  • Tubular – Available in varying lengths, these LED reproductions of radio tubes are used in ceiling fans, sconces, pendants, and steampunk lighting.
  • Oversized – These large bulbs are ideal for pendants and other fixtures where the bulb is clearly visible.

Speciality LEDs:

These bulbs contain several less popular shapes since they are only used for limited specific applications. The bulb shapes below reflect the most searched for in this group:

  • S (Straight-Sided) – S-shaped bulbs can be found in clear, frosted, or colored finishes and are commonly used in signs and patio light stringer. LED filament bulbs are also available.
  • T (Tubular) – Commonly referred to as miniature indicator bulbs, these bulbs are used to replace small halogen lights in automotive, instrument, or landscape lighting.

Types of Light Bulb Bases:

Once you know the shape of the LED bulb you’re looking to replace the next area of focus is identifying the base because buying a bulb with the wrong base will mean that it won’t fit in the lamp or fixture. LED light bulb bases fall into three main categories: Edison, bi-pin, and bayonet.

Edison – Edison base LED bulbs are the most popular, especially when looking to replace household light bulbs. The different Edison bases are labelled with an E followed by a number that indicates the width of the base in millimetres:

  • E12 = Candelabra base
  • E14 = Small Edison Screw base
  • E17 = Intermediate base
  • E26 = Medium base
  • E39 = Mogul base

Bi-Pin – Bi-pin bases are denoted with a “G” followed by a number which indicates the width of the space between the pins. Some of the most popular bi-pin bases are GU5.3 and GU10 which are found with MR16 LED bulbs. The GU5.3 bi-pin base just plugs into the socket while GU10s, as well as GU24 base, LED bulbs, twist and lock into place. There are also instances when there are letters following the number to indicate how many pins the bulbs have. “S” stands for single-pin, “D” stands for double-pin, “T” for triple, and “Q” for quadruple.

Bayonet – Bayonet base LED bulbs have notches on the side of the base which are used to lock the bulb into place. There are generally two different kinds of bayonet base bulbs, single contact (SC) or double contact (DC), which denotes if there are one or two contact points on the end of the bulb for electrical connectivity.


With traditional incandescent light bulbs, it was simple to make sure you were getting the right light bulb. If a 60-Watt bulb is the one that broke or stopped working, you’d just get another 60 Watt and call it a day. When it comes to LED lighting, it’s very different. Since LED light bulbs don’t use as much power that incandescent bulbs do, they are described in terms of incandescent equivalence; you may see an LED bulb described as a 60-Watt equivalent when it only uses 9.5 Watts. This is because LEDs are measured by Lumens (the total amount of visible light put out by a light bulb). There is not a direct mathematical comparison between the Lumen ratings used in LEDs and the wattage consumed by an incandescent. To fix this, a comparison of the average Lumen output of a standard wattage bulb is given to determine the wattage equivalence of an LED light bulb.

Also read: Commercial Lighting: 25 LED Shop Lights to Brighten up Your Workspace!

When looking at LED bulbs, wattage rating isn’t consistent across different bulb manufacturers. For example, some brands sell 60-Watt equivalent LED light bulbs that use 11 Watts; others only use 9 Watts while both will provide a similar Lumen output. If you’re upgrading to LED from an incandescent bulb, you’ll notice that an LED bulb of equivalent wattage will appear bright due to incandescent bulbs decreasing in Lumen output over time.

LED Color Temperature:

When you walk into a room and notice that it seems really warm or that it feels more like a hospital, you’re experiencing a difference in color temperature or light appearance. Lower values like the standard incandescent 2700K produce more yellow light, while higher values like 5000K create a bluer light. Most LED bulbs are available between 2700K and 5000K. Matching the right color temperature to the right room will make it easier to enjoy your time while in them. 

Soft White / Warm White (2700K – 3000K) – Recommended for use in:

  • Living Rooms
  • Bedrooms
  • Rooms decorated in earthy tones (reds, oranges, and yellows)

Cool White (3500K – 4500K) – Recommended for use in:

  • Kitchens
  • Bathrooms
  • Rooms decorated in airy, fresh hues (blues, greens, whites)

Daylight / Full Spectrum (5000K – 6500K) – Recommended for use in:

  • Garages
  • Offices
  • Craft room
  • Rooms where productivity is key

Prime Features of LEDs:

There are some aspects of buying a light bulb that you have to know in order to make sure that you buy the right one, aspects of the bulb might vary from one light bulb to another, even if they look the same. All of this information can be found on product pages online or on the bulb box if you are shopping in a store.

Dimming: Most people are used to only turning light bulbs on and off, but some people enjoy being able to take a bright room and tone it down to set the right mood and vice versa. The problem is that not all LED light bulbs are dimmable and even those that are dimmable won’t work with every dimmer. Realizing this, manufacturers provide a list of dimmers that they’ve tested to ensure compatibility. If you have older dimmers in your home or office, there’s a good chance you’ll have to look through a few different brands of LEDs to find one that’s compatible with your dimmers if you aren’t looking to upgrade them. Pairing an LED and an incompatible dimmer can lead to performance issues. Since not everyone needs the ability to dim, so you can save money by buying LED bulbs that don’t dim.

CRI: Color Rendering Index (CRI) is a scale from 0 to 100 that measures the ability of a light bulb to reproduce colors compared to noon-sunlight. Incandescent bulbs are rated at 100 and many LED bulbs are usually rated somewhere between 80 and 85. This means that if you were to swap an incandescent for an LED bulb the colors wouldn’t look as good, but the savings outweigh this trade-off in most circumstances. However, if color accuracy is important to you, look for LED bulbs with a CRI of 90 or above. In most settings, including museums, the difference between a 100 CRI and 90 CRI is not noticeable by most people.

Life Hours: For LED bulbs, that rating is decided based on how long it will take to stop producing 70% of its lumen output. Many LED bulbs are rated for 15,000 – 25,000 hours. Some bulbs on the market will last as long as 50,000 hours. These differences could account for years of use from an LED light bulb, so it’s good to know what this number is since a lower number of life hours could explain why one bulb is priced differently than another.

Final thoughts:

The lighting industry, in general, expects LED costs to come down quickly. Many scientists, and companies that develop and manufactures LED lighting, estimates a 50 percent price reduction within two years from now. Businesses or shops which have high lighting expenses can recoup bulb expenditures very quickly, will likely flock to LEDs if the price drops to 50 percent. However, many homeowners may wait until the bulbs hit the $3 mark.