Lumen to Watt Calculator

What are Lumens and Watts?

Lumen (lm) is the SI unit of luminous flux, which measures the total amount of visible light emitted by a source. Watt (W) is the SI unit of power, which measures the rate of energy transfer. In lighting, watts are used to indicate the power consumption of a light source.

The Lumen to Watt Formula

The formula for converting lumens to watts is:

\[P = \frac{\Phi}{\eta}\]

Where:

• \(P\) = Power (watts)
• \(\Phi\) = Luminous flux (lumens)
• \(\eta\) = Luminous efficacy (lumens per watt)

Step-by-Step Lumen to Watt Calculation

1. Identify the luminous flux in lumens (\(\Phi\)) and the luminous efficacy in lumens per watt (\(\eta\)) for the light source.
2. Apply the formula: \(P = \frac{\Phi}{\eta}\).
3. The result is the power consumption in watts (\(P\)).

Example Calculation

Let's calculate the power consumption for a light source with 1000 lumens and a luminous efficacy of 100 lm/W:

1. \(\Phi = 1000 \text{ lm}\), \(\eta = 100 \text{ lm/W}\)
2. \[P = \frac{1000 \text{ lm}}{100 \text{ lm/W}} = 10 \text{ watts}\]

Visual Representation

This diagram illustrates how a light source with 1000 lumens of luminous flux consumes 10 watts of power, given a luminous efficacy of 100 lm/W. The yellow circle represents the relative brightness of the light source.