LUMENS TO WATTS CHART FOR LED OUTDOOR LIGHTING

1. What is Lumens

2. What is Watts

3. Lumens to Watts: How to Convert

4. Luminous Efficiency Comparison

5. How many lumens do I need for outdoor lighting?

6. Choose the most suitable lights

7. Conclusion

When searching for the best lights for outdoor lighting, many people think about the watts ofo the lights, and they usually use the wattage as a measure of brightness. With the development of CFL and LED technology, the watts to brightness is no longer so important. What you need to pay attention to now is the lumens parameter which can directly reflect the brightness of the high efficiency outdoor flood light or spot light. Let's learn more about lumens and the difference between lumens and watts in this article.

Here we have a Lumen to Watt Conversion Chart for your reference.

1. What is Lumens

Lumen is "equal to the amount of light emitted per second in a unit solid angle of one steradian from a uniform source of one candela", it's a unit for measuring the rate of flow of light. In simple terms, lumen is the total amount of light produced and directly reflects the brightness of the light. The larger the lumen parameter value, the brighter the light, and the smaller the parameter value, the darker the light. 

Lumens equals to the amount of light output.

Lumens is a more accurate unit of measure than watts. It can help us to differ the performance of the light fixture no matter how is the power source. Due to more advanced lighting technologies appearing, lumens are now a common unit for measuring the brightness of lamps. 

Here is an simple example to show the difference between the incandescent lamps and LED lamps. For an incandescent lamp, per watt of input power can only generate 20 lumens of output power. However, a LED wall wash light can produce 100 lumens output light with per watt input. The emergence of LED lights helps to save more energy.

2. What is Watts

Watt is "equivalent to one joule per second, corresponding to the rate of energy in an electric circuit where the potential difference is one volt and the current one ampere." Simply put, the watts is the measure of the power consumed by the lamp, reflecting the input power of the lamp. Since there were only incandescent and fluorescent lamps before, their energy conversion rates were similar. The higher the wattage of incandescent and fluorescent lamps, the brighter the lamp. Therefore, people can judge the brightness of the lamp according to the wattage of the lamp, so as to buy the appropriate outdoor lighting. 

Why is wattage a measure of the brightness of incandescent and fluorescent lamps? The light-emitting principle of incandescent lamps is that the current passes through the filament in the lamp, and the filament is heated to emit light. The higher the input watts, the brighter the output light. Fluorescent lamps contain mercury and phosphors. When an electric current is applied, discharges will be generated in the rare gas, and the phosphors will be excited to emit light. The higher the watts plugged in, the more current is passed through it, and the brighter the fluorescent light is.

With new CFL and LED light fixtures emerging, very little input power is required to produce the same brightness of light, so the watts unit of measure is no longer a selection criterion for newer light fixtures.

3. Lumens to Watts: How to Convert

When you're looking for the right light fixture for your outdoor LED lighting project, in addition to the type, shape, and color of the light, you also need to consider the light's lumen parameter. Sometimes, you may not find the lumens on the LED light label directly, so you need to convert the lumens to watts and then compare the watts.

It can be calculated by this simple formula：Watts=Lumens/Lumen per watt

After knowing the lumens and watts, now we can come out with the lumens per watt. Lumens per watt means the efficiency of converting energy (watts) into light (lumens).  The conversion efficiency of old tungsten incandescent lamps is about 15~20 lumens per watt, but new LED light fixture can achieve the conversion efficiency to 70~110 lumens per watt. Therefore, the conversion rate of electric energy to light energy of LED lights is about 6 times that of incandescent lamps.

If you now want to replace a 60W incandescent lamp with an LED lamp, what wattage should you choose?

According to the conversion ratio of LED lamp is 6 times that of incandescent lamp, LED lamp: incandescent lamp=6:1, just divide 60 by 6, so 10W LED lamp is fine. 

Of course, this calculation is only for the general situation, and the luminous efficacy of LED lamps provided by different manufacturers is not exactly the same. Please check the detailed parameters of the LED lights to get the exact result.

4. Luminous Efficiency Comparison

Different lamps have different luminous effenciey. And here is a Luminous Efficacy Comparison Chart to compare the difference between the incandescent, halogen, fluorescent, and LED light.

5. How many lumens do I need for outdoor lighting?

How many lumens you need depends on where you place your LED fixtures and what kind of lighting effect you want.

Here are some tips for you to choose:

landscape spot lights: 100-480 lm

Floodlights: 960-2500 lm

Step linear lights: 100-240lm

Swimming pool lights: 200-450lm

Landscape path lights: 150-340lm

5.1 Landscape lighting

Landscape lighting refers to outdoor lighting projects that have both lighting functions and artistic decoration and landscaping functions. Landscape lighting usually covers a wide range and requires overall specifications, such as individual key lighting such as small scenes and buildings. Therefore, the lighting methods are diverse and the selection of luminaires is also complicated. The number of lumens required for landscape lighting is selected according to the role of the landscape. If using a spotlight to accentuate a landscape, usually it needs to choose 120-200 lumens. If installing path lights to illuminate sidewalks, 180 to 320 lumens is recommended. The path lights can be used to illuminate the whole path or it can also be used for decoration. If mainly for illumination, you should choose higher lumens for safety considerations. If the light is for decorative purposes only, choose low lumens to create a beautiful scenery. 

5.2 Architectural lighting

Architectural lighting design is an integral part of the overall design and an important means to add luster to the building. Architectural lighting design is based on the visual needs of consumers, transforming and beautifying buildings with the ingenious mobilization of light and shadow to create a beautiful and comfortable visual environment for people. The lighting methods commonly used in architectural lighting are: light projection lighting, outline lighting, translucent lighting, flood lighting, hybrid lighting.

Light projection lighting illuminates the building surface through floodlights installed outside the building, which not only achieves energy conservation and environmental protection, but also displays the overall shape, three-dimensional effect and material of the building. In addition to the reasonable setting of the projection direction and angle of the lighting fixtures, it is also necessary to select the appropriate lumens, and pay attention to the control of the illuminance and brightness of LED building facade lighting. Typically, this requires high-lumen floodlights to illuminate the target building for overall lighting.

Outline lighting was to install incandescent lamps continuously at certain intervals to form a light band effect in the past, but the choice is to use LED linear lights to outline the outline of the building. For modern buildings with rich contours or buildings with distinctive shapes, a combination of contour lighting and local flood lighting should be adopted.

Translucent lighting is to make full use of indoor lights at night to form a luminous surface or luminous strip lighting on the glass, and let the light transmit to the outside of the building through the glass and glass curtain wall. The internal light transmission lighting method is especially suitable for buildings with glass curtain wall structure. In order to avoid dazzling lights coming out from the inside, please adjust the appropriate beam angle, and do not choose LED lights with too high lumens.

Flood lighting is a light source that uniformly illuminates in all directions with an adjustable illumination range to produce shadows to highlight the undulations of the building facade. The shadow scale of flood lighting depends on the undulations of the building surface and the incident angle of the light. The average lighting direction angle is 45°. If the building surface has small undulations, the incident angle must be greater than 45°. Floodlights are usually installed as lighting fixtures for safety purposes, and the DMX RGB flood light are usually used for media lighting and building facade decooration. Floodlights with narrow beam angles such as 15°, 25° (they are also called exterior LED spot lights) are used to illuminate a specific small place, and 45° and 60° floodlights can illuminate large areas, such as an entire wall or a parking lot. If you need to light a trail in your yard, you only need to choose a floodlight with a low lumen value, such as 300 to 400 lumens. But if you want to illuminate an entire area, choose an outdoor LED floodlight with a larger beam angle and higher lumen value. Floodlights with 800 to 1500 lumens are recommended for lighting the entire yard in front of the door. The brighter the lights and the more lumens they emit, the safer your space will be. 

Hybrid lighting mainly adopts the combination of edge outline and flood lighting, fully based on the morphological characteristics of the building, and comprehensively uses a variety of lighting techniques to create a beautiful architectural visual art image. For mixed lighting, special attention should be paid to controlling the exit direction of the light and selecting high-lumen LED lights to illuminate the building as much as possible.

Here is a Lumens to Watts conversation chart for your reference.

6. Choose the most suitable lights

Focus on lumens not watts：Calculate out the total lumens needed to fully illuminate the project. If you are considering replacing an old incandescent bulb or a halogen bulb, match the lumen with a new LED light. When looking for a outdoor LED floodlight or linear light, the wattage doesn't make sense because the latest technology uses much less wattage than older light fixtures. If you want to replace a 40W incandescent bulb, an LED bulb with 600 lumen output is ideal. Likewise, to replace a 150W incandescent light, you can opt for a 3000 lumen LED light. For large-scale replacement of LED-equivalent lumen lighting equipment, factors such as optics, ambient temperature, and lumen attenuation should also be considered. 

Useful Lumens: This means the total lumens of light emitted from a specific angle to a place. For example, a 100W incandescent lamp emits 1400 lumens in all directions as a street light. Since you don't need to waste light energy in all directions, opt for LED fixtures with a fixed beam angle instead. hen looking for LED lights, you don't need 1300 lumens of LEDs, just 700-800 lumens is enough, because that's the total luminous flux for directional lighting.

Choose the right color temperature：2700~3000K is called warm white, it actually looks like yellow color. The most suitable LED color temperature to replace incandescent bulbs is 2700~3000K. 3000~5000K are cool colors and daylight colors, and 5000K-6500K are suitable for lighting spaces that require strong light. Vieiw more details about choosing the right color temperature: 3000K 4000K 5000K

Think about the CRI: color rendering index (CRI) is a quantity that describes the ability of a light source to render the color of real objects. When using CFL lamps and fluorescent lamps, you need to more attention on this. For LED lights, The higher the color rendering index, the lower the brightness. In outdoor lighting, a certain degree of color rendering is required while ensuring brightness. Suntech recommends LED outdoor fixtures with a CRI of 70 or 80. To know more about CRI, please click CRI 90 VS CRI 80 VS CRI 70 to have a look. 

Each outdoor space has its own lighting requirements, so different levels of lumens are required to achieve the overall desired effect. The required lumens (brightness) depends on the luminaire and its purpose in the setup. For example, spotlights used to highlight particularly important features in a landscape may require a lamp with a higher light output, whereas a linear light for decoration need lower brightness. In fact, choosing a light with very high brightness can cause problems in some cases. For instance， street lights that are too bright will have a glare effect that affects the driver's vision. When browing our "Facade LED Lighting" products, you can find the lumens and watts parameters in the product details, and we also provide customize the lumens and color temperature as your requests. 

Here are several recommendation for your outdoor landscape and facade lighting projects.

Outdoor Indoor Architectural Linear LED Lighting

Outdoor LED Wall Washer Light

CREE RGB Programmable LED Flood Light 

DMX LED Pixel Point Light For Facade Lighting

View more products: DMX LED dot lights | LED mesh screen | architectural flood light | DMX controlled spotlight | LED pixel bar DMX

7. Conclusion

With the development of lighting technology, the luminous efficiency is rising and the power consumption is decreasing. LED lighting is a more energy-efficient option. Suntech is a professional LED outdoor light supplier and manufacturer, focusing on architectural lighting and landscape lighting in China, our main products are LED flood light, LED spot light, LED linear wall washer, and LED media mesh.  Don't hesitate to inquire us for your lighting project now!

Here are some knowledges that you may interested in:

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