Can A Lux Meter Measure LED Light?

One can have too much of a good thing. Such as light.

You may think that the more light around you, the better, that is not always true. You may find the lesser the light, the better, in some cases.

So that brings you to the need to carefully measure the brightness of light around you. How can you do that? With a lux meter or lumen meter, of course!

If you are an art enthusiast, you may need to display your artwork under precise lighting conditions. Neither too bright to damage the delicate dyes in the paint, nor so dim that you cannot make out the colors.

You are a road authority worker and need to make sure the street lighting is at the correct brightness. It needs to be bright enough to increase visibility and prevent accidents, while not too excessive, causing light pollution and high energy bills.

But more commonly, light meters are being used for reaching optimal light settings for growing indoor plants. Sometimes these plants require colored lights, and more and more people are opting for LED grow light due to its energy-efficient features.

Lux meters can detect and measure all white light, especially from the sun or incandescent bulb. Lux meters are unable to accurately pick up LED light as LED lights have a higher blue light wavelength. Additionally, lux meters will not be able to tell the luminosity of blue, red or purple LED lights.

What Is The Lux Meter?

lux meter

The lumen meter or lux meter tells illuminance in the unit of lumens, lux, or foot candle. The handheld device measures how much luminous flux is spread over a given area.

A measure of one lux is equal to one lumen per square meter.

The device has a sensor at the front that detects illuminance and converts it into an electrical signal that displays a number to show the lux.

You place the meter onto the room’s surface where you want the reading, such as a tabletop. The light reflects off that surface for the reading. If it is kept hovering, the readings will be inaccurate.

The lux meter will measure the total light output. This measurement is also found on the boxes of bulbs that you can compare and then purchase.

A lux meter is also unable to accurately detect the red and blue light wavelengths. It will best show the measure of green and yellow light in the visible spectrum of sunlight or incandescent light.

So if you are using grow lights that need accurate purple light, a lux meter may not detect the intensity of the purple light, causing your plants to burn.

Can Lux Meter Measure Any LED Colors?

rgb concept

As I explained above, lux meters cannot pick up the color wavelengths of the entire visible spectrum.

So, in essence, lux meters only is a measure for white light. To make matters more complicated, lux meters will more heavily detect green light.

Now adding to that, you might know that LEDs are known to contain more blue light wavelength than other colors.

Also read: What Is The Difference Between LED And Laser Diode?

Therefore, a lux meter cannot accurately display the intensity of an LED, especially if the LED is monocolored blue or red light, and certainly not when it is a mixed purple light.

However, with the growing use of LED lights, there are special LED Lux Meters that adjust the settings and correct for errors using calculations on V-Lambda graphs and display the lux as accurately as is possible.

They also give separate readings for the red, blue, or green colors present in the light being measured.

Here is one such example of a calibrated LED light meter (Amazon) that can pick up colored LED lights.

Many people also use their phone apps for measuring lux. Again, this is not very accurate because it may not be ‘cosine corrected’ to show the different colors in the light.

If you are measuring high CRI white LED light, a lux meter may be a cheaper option.

What Is The Difference Between PAR And Lux Meter?

In the world of growing indoor plants, grow lights are extensively used. Here again, optimal light levels need to be maintained to allow the plants to thrive.

A device that allows this is called the PAR meter, short for Photosynthetically Active Radiation. It measures the light intensity within the spectrum that plants use most to photosynthesize, between a spectral window of 400 nm to 700 nm.

PAR meters detect all light in the entire visible spectrum, from after the ultraviolet rays till the infrared radiation begins, including all the colors.

It is highly accurate to measure light intensity of grow lights.

It also does not need to be calibrated to each new light source, so it can be easily taken around and used to measure different bulbs’ illuminance relative to each other.

With a lux meter, you are limited to one kind of light, which is the light you have calibrated your device to. It would need to be recalibrated for each new type of light. Even then, it will not tell you the relative difference in illuminance between the two different light sources.

PAR meters are more expensive than lux meters, but if you are a true hobbyist or grow plants for a living, investing in a PAR meter will greatly benefit you in the long run. Here is a full-spectrum quantum meter (Amazon), or PAR meter, fan-favorite that growers have used with success.

Final Words

Light and photo spectrometry are commonly used worldwide to make our lives easier and our sight better. It is also essential for growing indoor plants with the most efficiency.

Now you have a fair understanding of how you can also use tools that measure these spectrometer readings.

Are you planning on getting grow LED lights for your plants?

Have you used a lux meter or a PAR meter before?

Share your experience with me in the comments below.