1. What is a Lumens to Watts Calculator?

Definition: This calculator converts luminous flux (lumens) to power consumption (watts) based on the efficacy of the light source.

Purpose: It helps compare energy efficiency of different lighting technologies and estimate power requirements for lighting installations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( W \) — Power in watts (W)
• \( L \) — Luminous flux in lumens (lm)
• \( E \) — Efficacy in lumens per watt (lm/W)

Explanation: The luminous flux is divided by the efficacy to determine the electrical power needed to produce that amount of light.

3. Importance of Lumens to Watts Conversion

Details: This conversion helps in energy-efficient lighting design, comparing different light sources, and estimating electricity costs for lighting.

4. Using the Calculator

Tips: Enter the luminous flux in lumens and the efficacy (default 80 lm/W for typical LED bulbs). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is efficacy in lighting?
A: Efficacy measures how efficiently a light source produces visible light, expressed in lumens per watt (lm/W).

Q2: What's a typical efficacy for different bulbs?
A: Incandescent: 10-17 lm/W, CFL: 50-70 lm/W, LED: 80-120 lm/W, High-efficiency LED: up to 200 lm/W.

Q3: Why convert lumens to watts?
A: To compare energy efficiency of different lights and estimate power consumption when you know the desired brightness.

Q4: How do I find the lumens of a bulb?
A: Check the packaging or product specifications - lumens are now the standard measure of light output.

Q5: Does higher efficacy always mean better lighting?
A: Not necessarily - color quality, CRI, and light distribution are also important factors in lighting quality.