1. What is a Lumens to Wattage Calculator?

Definition: This calculator estimates the electrical power (wattage) needed to produce a given amount of light (lumens) based on the efficacy of the light source.

Purpose: It helps compare lighting efficiency and estimate energy requirements when switching between different lighting technologies.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( W \) — Electrical power (watts)
• \( L \) — Luminous flux (lumens)
• \( E \) — Luminous efficacy (lumens per watt)

Explanation: The luminous flux is divided by the efficacy to determine the required electrical power.

3. Importance of Wattage Calculation

Details: Proper wattage estimation helps in energy-efficient lighting design, cost savings, and comparing different lighting technologies.

4. Using the Calculator

Tips: Enter the total lumens needed and the efficacy of your light source (default 100 lm/W for typical LED). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is luminous efficacy?
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: 40-70 lm/W, LED: 80-120 lm/W, High-efficiency LED: up to 200 lm/W.

Q3: Why calculate wattage from lumens?
A: Modern lighting focuses on lumens (light output) rather than watts (energy input). This calculation helps determine energy needs for desired brightness.

Q4: How do I find the lumens of my current bulbs?
A: Check the packaging or manufacturer specifications. Older bulbs often list watts only - use approximate conversions (e.g., 60W incandescent ≈ 800 lumens).

Q5: Does this account for real-world conditions?
A: No, consider that actual performance may vary based on temperature, age of bulbs, and fixture design.