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How to Choose Lighting Fixtures? Lumen vs Watt vs Lux vs Candela vs Efficacy

Lumen vs Watt


When talking about lights, wattage is the most common term used. But in modern times, lumens are far more significant than watts.


People are attempting to purchase energy-efficient lights and spend as little as possible for the maximum amount of light output due to trends towards greenness and energy efficiency. LED lights are more and more popular on market. With LED, it is no longer necessary to determine a lamp's brightness by its wattage because LED lamps consume up to 85% less energy (watts) while still producing the same amount of light. Instead, we use lumens to describle the brightness.




So what do watts actually mean?


There are just two occasions when you ever need to know a light's wattage, which is used to describe the amount of energy it consumes.



Your electric bill is the first thing which needs to refer to watt. If you want to calculate your electricity bill, you must first determine how much power the light would use in an hour, take into account the lamp's wattage, and then base your calculation on the wattage.


In order to determine how many fixtures may be connected to a single circuit, you will also need to take into account wattage. For example, you have up to 2400 watts to deal with on a circuit since 20 amps results in 120 volts, which is 2400 watts. Although loading things up that manner isn't always a good idea, at least it offers you a calculable solution.


But what if we want to find out how bright a light is?


The Lumen is given to most of the people. The majority of people think that a light becomes brighter and performs better the more lumens it has. But is it the case?


What is the lumen, and why are we hearing about it so much these days?

A lumen is a fundamental measure that is used to describe the total amount of light that an LED chip is capable of producing. The manufacturer of the LED chip frequently provides us with this value.

Solar Light Bulb
A lumen is a fundamental measure that is used to describe the total amount of light that an LED chip is capable of producing


If the light has 40000 lumens, it will have the same floodlight intensity as Niagara Falls emanating from that fixture, illuminating the whole area. With a 150 lumen light, photons are released from the light bulb in the form of a trickle. The interesting thing is that both of those lights might have the same wattage.


lumens and light output
Different Lumens have different light outputs

You can determine how many lights you'll need by looking at a light's lumen rating. Higher lumen output lights allow you to purchase fewer fixtures and maybe save more money on installation. Or, if you like a lower brightness, you may select lights with fewer lumens and add more fixtures at the same time to create a delicate design pattern without making yourself blind.


The lumen rating is only a measurement of the light's unprocessed potential. The geometry, the size of the reflector, the clarity of the lens, and a few other factors that went into the design and engineering of the light are not taken into consideration.


Despite having the same lumen, lights can have varying outputs depending on their design. We shall discuss it later.



Definitions of additional metrics for evaluating and measuring light output


Lumens alone are insufficient to choose the finest lighting for your purposes; you must also consider other metrics in addition to lumens.


In addition to Lumen, Lux and Candela are also used to estimate a light's output. Additionally, lighting efficiency is assessed using efficacy. When you need to buy a light, a good understanding of them may assist you evaluate the performance of a light.



Lumen VS LUX

The total quantity of light that LED light beads emit is measured in lumens. The term "lux" describes the actual quantity of light falling on a surface at a certain distance. It is meaningless without knowing the distance.


The light brightness decreases with increasing distance from the source of illumination. So you have to know the distance to evaluate the light


Now, Lux is commonly measured on a wall inside one square meter from a distance of ten meters. It is quite easy to do so; you just take a light, shine it on a wall, and then measure the amount of light that is emitted over a surface area of one square meter on that wall.


Some people can be confused by how the lighting range changes the lux. Because a spot beam light is designed to cast light out extremely far into the distance, it has a concentrated hot spot that is very bright, and its lux value will be much higher than that of, say, a spread beam light. A spread beam light will have a lower Lux rating merely because it is made to spread light out over a much larger area, not because it is a bad light.



A CFL bulb is listed at 1600 lumens in this instance, however its light output is dispersed 360 degrees in all directions. Therefore, even there are spotlights have the same lumen, the Lux of the CFL may be lower. However, there are always ways to make it better. If I use two of these CFL bulbs, or even four, I will obtain a light output that is doubled or quadrupled.


We also compare them with the 4 foot tube light, which has a 2850 lumen rating. If we use two tube lights together, that will be 5700 lumens.


However, their Lux is equal to utilizing two CFL lights after measuring. You might be asking why their lux levels are the same, if two tube lights have 5700 lumens and two CFL bulbs have 3200 lumens. The tube light will have a lower lux since it is longer than a CFL bulb and can illuminate a larger space.


Lux is a useful unit of measurement for light because it both accurately captures the effects of light in the actual world and also takes into account the engineering, design, and other aspects of the light.


Lumen VS Candela

The candela, which is the total quantity of light contained inside a specific beam angle and direction, allows us to quantify the volume and luminous intensity of a light.


The main distinction between lumens and candela is that whereas candela refers to the intensity of the light in a certain direction, lumens relate to the overall production of visible light.


Both the terms "candela" and "candle power" pertain to earlier eras when candles served as the mainl light source of illumination. Now, you should be aware that a single wax candle has a Candela rating of 1, which is a fairly good comparison.


Efficacy Rating

Efficacy is another crucial factor to consider when choosing lights. It simply refers to the efficiency of how much energy this lamp will use compared to the amount of light it will produce. If it has a low effectiveness rate, such as 20 lumens per watt, it signifies that you only get 20 lumens for every watt used. In order to assess the working effectiveness of the light, efficacy is crucial.



As an illustration, we have three different lamps that each provide 1,000 lumens: an incandescent, a CFL, and an LED. However, an incandescent bulb needs 50 watts of power to produce 1,000 lumens of light. An LED bulb may only require 12 watts, effectively providing the same amount of light. Additionally, you probably need 16 to 18 watts for the CFL lamp to produce the same amount of light.


Let's calculate at the lumens produced by one watt. An LED light is extremely efficient, producing 80 lumens for every watt. The lumens per watt for incandescent lighting are most likely 20. Therefore, understanding efficacy rates is helpful


When deciding which light to purchase and which one will serve your purpose the best, it is often quite helpful to comprehend all of these parameters that help us estimate the overall product. You may also get some direction by checking at the lumen, lux, candela and efficacy values for light.


More about Lumens

Outdoor LED lumens range from 12 to 1300 depending on where you install the lights and how bright they need to be. Following are the brief introduction for different types of lighting.

Different Lumens
Different Lumens


Patio Lights

Decorative, less bright and emit fewer lumens

Ambient Lighting such as string lights, outdoor wall lights, post lights, outdoor hanging lights or other lights for living room, task lighting such as lights for kitchen island or dining table in dining room.



Landscape Lighting

Available in variety of lumens for decorative or security purposes

Pathway lights, Recessed Lighting and spotlights designed to illuminate outdoor landscapes



Flood Light

Great for security with 700-1300 Lumens and motion sensors

Wall-Mounted Flood Lights Brighten Pathways & Area Flood lights illuminate larger areas



Requires no electricity or maintenance

Energy-efficient LED Lights powered by the sun



Now you may find many products that don't even list Lux, especially when looking at commercial lighting like CFLs, LEDs, or tubes and thrusts. You can try to find the lumen description. Although it may not be particularly helpful to us, architects and designers of industrial lighting will find it quite helpful.


They can calculate the total number of lumens required to illuminate a sizable office area during the day or a sizable warehouse using highly complex algorithms and tables. You surely don't want to get your estimates incorrect when you have to order thousands of fixtures and lights to illuminate every floor of a skyscraper.



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