Lux to Watt Calculator

What is Lux and Watt?

Lux (lx) is the SI unit of illuminance, which measures the amount of light that falls on a surface. Watt (W) is the SI unit of power, which measures the rate at which energy is transferred.

The Lux to Watt Formula

The formula for converting lux to watts is:

\[P = \frac{E \times A}{\eta}\]

Where:

• \(P\) = Power (watts)
• \(E\) = Illuminance (lux)
• \(A\) = Area (m²)
• \(\eta\) = Luminous efficacy (lm/W)

Step-by-Step Lux to Watt Calculation

1. Identify the illuminance in lux (E), the surface area in square meters (A), and the luminous efficacy of the light source in lumens per watt (η).
2. Multiply the illuminance by the area: \(E \times A\)
3. Divide the result by the luminous efficacy: \(\frac{E \times A}{\eta}\)
4. The result is the power in watts (P).

Example Calculation

Let's calculate the power required for a light source to produce 500 lux over an area of 20 m² with an LED lamp (efficacy of 100 lm/W):

1. \(E = 500 \text{ lx}\), \(A = 20 \text{ m}^2\), \(\eta = 100 \text{ lm/W}\)
2. \[\begin{align} P &= \frac{500 \times 20}{100} \\ &= \frac{10000}{100} \\ &= 100 \text{ watts} \end{align}\]

Visual Representation

This diagram illustrates how a 100-watt LED light source produces an illuminance of 500 lux over an area of 20 m². The yellow circle represents the light source, and the triangle shows the spread of light over the given area.