Illuminance Calculator: All-to-know about Calculating Illuminance

When it comes to installing light bulbs or adjusting the brightness of your computer screen, knowing how bright the light is will help you determine how effective they are.

The illuminance of a surface, which is different from luminance, is the amount of light that falls on it, whereas luminance is the amount of light reflected or emitted from it. When it comes to brightness and electricity, staying clear on terms might help you make more innovative selections. 

Let’s find out the illuminance calculator and all related information in this article!

Illuminance Calculation

Illuminance Calculation

Illuminance is a measurement of how much light reaches a specific region. In this scenario, the total number of installed light sources in the entire room is essential. The illuminance of a luminaire is a receiving size, while the luminous flux is a sending size.

The illuminance is measured in Lux.

1 lux (lx) equals 1 lumen per square meter or 1 lumen per 10.76 square feet of luminous flux.

Illuminance Calculator

The illuminance on a surface is 6 lux and the surface is 4 meters from the light source. What is the intensity of the source?

You might visualize the light source as the center of a sphere with a radius equal to the distance between the light source and the item since light travels in a radiating manner. This means that the sphere’s surface area that matches to this arrangement should be used as the equivalent surface area.

Multiplying the sphere’s surface area with radius 4 as ​4π42​ m2 by illuminance 6 lumen/m2 gives you 1206.37 lumens of flux ​Φ​ . The light travels directly to the surface, so angular span ​Ω​ is ​4π​ candelas, and, using ​Φ = I x Ω,​ the intensity ​I​ is 15159.69 lumens/m2.

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Calculating Illuminance 

Calculating Illuminance 

Illuminance is the quantity of light that falls on a surface in foot candles or lux units. The SI unit of lux is approximately 0.0929030-foot candles. 1 lux is also equal to 1 lumen/m2, where a lumen is a unit of luminous flux, or the quantity of visible light emitted by a source per unit of time, and 1 lux is also equal to.0001 phot (ph). These units allow you to use a variety of scales to determine illuminance for various reasons.

You can calculate the illuminance ​E​ related to luminous flux “phi” by​ using E= Φ/A (over a given area ​A​). This equation denotes luminous flux with ​Φ​, the same symbol for magnetic flux; it shows similarity to the equation for magnetic flux).

Φ=BA (for a surface area parallel to a magnet ​A​ and magnetic field strength ​B​. This means illuminance parallels the magnetic field in the way scientists and engineers calculate it. You can convert the units of illuminance (flux/m2) directly to watts using the intensity (in units of candelas).

Φ=I×Ω (for flux ​Φ​, the intensity ​I​ and angular span “ohm” ​Ω​ for the angular span in ​steradian (sr)​, or square radian, and an entire sphere has an angular span of ​4π​. The light calculated in illuminance falls onto the surface and spreads out, causing the object to become bright, so illuminance may be used to measure brightness).

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Calculating Other Values

Calculating Illuminance

The candela, which is employed in the angular span, measures the amount of light emitted by a light source over a three-dimensional range. As illustrated in the example, the angular span is measured in steradians over the surface area to which the light is applied. The steradian of a complete sphere is 4 candelas. Make sure you do not get the terms “lux” and “candela” mixed up.

The lux is a measurement of the illumination of the surface, whereas the candela is a measurement of the angular span. The lux decreases when one moves further away from a light source since less light can reach that location.

This is significant in real-world applications and precise computations that must account for the particular light source, such as the tungsten wire of a light bulb rather than the light bulb itself. Depending on the size of your calculations, the distance between smaller light bulbs, such as specific LED light sources, may be minimal.

One steradian of a sphere with a radius of one meter would encompass a surface area of 1 m2. This can be calculated by remembering that an entire sphere covers 4 candelas; therefore, for a surface area of 4 (from 4r2 with a radius of 1) steradians, the sphere would cover 1 m2.

Calculate real-world examples of light bulbs and candles emitting light using the surface area to account for the light’s geometry to employ these conversions. Then they can be linked to brightness.

While illuminance refers to the amount of light that strikes a surface, luminance refers to the amount of light emitted or reflected by that surface in candela/m2 or “nits.” The luminance ​L​ and lux ​E​ values are related through an ideal surface that emits all light with the equation ​E = L x π​.

Read More: Lux Lumens Conversion – What to pay attention to?

Using a Lux Measurement Chart

(Online Calculators)

If having so many ways of measuring the same thing seems onerous, online calculators and charts can help by doing calculations to convert between different units. Look Lamp has a lumen-to-watts calculator that may be used to figure out how much power is needed for various light standards.

These numbers are displayed in a table on the website so that you may examine how they compare. When conducting these conversions, keep in mind the units of lumens and watts, as well as the luminous efficacy by “etaη.”

The EngineeringToolBox also includes a lux measuring chart and methods for determining illuminance and illumination for the light bulb and lamp standards. Illumination is a method of calculating illuminance that relies on the lamp or light source’s electrical specifications rather than experimental measurements of light emitted.

Another way to determine illuminance is by illumination, which substitutes electrical standards for the lamp or other light source for experimental measurements of the light emitted. The equation for illumination I provides it as:

The equation for illumination

Lighting Efficiency

As computed by the Look Lamp website, the luminous efficacy of radiation is a typical way of describing how well a light bulb or other light source uses its energy resources. However, the official technique for assessing light source efficiency is luminous efficacy, not radiation.

Lighting efficiency is usually expressed as a percentage, with the maximum theoretical value of lighting efficiency being 683.002 lm/W, which emits light with a wavelength of 555 nm. For example, a typical current white-watt “limited” light source can achieve over 100 lm/W with a 15 percent efficiency, which is higher than many other light sources.

15W LED lightbuld
15W LED lightbuld

In research and engineering, measuring luminance and illuminance considers how the eyes perceive light brightness to produce more precise, objective measures. Experiments are used to examine the distribution of light brightness to determine whether the response to brightness is due to a cone or rod photoreceptor signals within the human eye.

Photometry research, for example, aims to detect specific types of light based on their response linearity. If two light fluxes (1 and 2 produce two separate signals, photometry detectors measure the signal produced when both fluxes are summed linearly. The response linearity measures this relationship’s linearity.

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This data will assist you in calculating the illuminance in lux. The illuminance calculator tool can assess or plan lighting projects in rough detail. On the other hand, a professional lighting design is required to account for all elements, such as the best possible positioning of light sources, the appropriate distance, and the room’s reflection behavior.

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