1. What is a Watts to Lumens Calculator?

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

Purpose: It helps compare different lighting technologies and estimate brightness when switching between bulb types.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Lumens (lm) — Total visible light output
• Watts (W) — Electrical power consumed
• Efficacy (lm/W) — Light output per watt of power

Explanation: The formula shows how efficiently a light source converts electricity into visible light.

3. Importance of Lumens Calculation

Details: With LED lighting, watts no longer indicate brightness as they did with incandescent bulbs. Lumens provide an accurate measure of light output.

4. Using the Calculator

Tips: Enter the wattage of your bulb and its luminous efficacy (default 100 lm/W for typical LEDs). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is typical efficacy for different bulbs?
A: Incandescent: 10-17 lm/W, CFL: 50-70 lm/W, LED: 80-150 lm/W, High-end LED: up to 200 lm/W.

Q2: Why is efficacy important?
A: Higher efficacy means more light per watt, resulting in lower energy bills for the same brightness.

Q3: How many lumens do I need for a room?
A: Living rooms typically need 1,500-3,000 lm, kitchens 3,000-6,000 lm, bedrooms 1,000-2,000 lm.

Q4: Where can I find a bulb's efficacy?
A: Check the product packaging or specifications, usually listed as "lumens per watt."

Q5: Does this work for all light types?
A: Yes, but efficacy values vary significantly between technologies (incandescent, halogen, CFL, LED).