1. What is a Candela to Lumens Calculator?

Definition: This calculator converts luminous intensity (candela) to luminous flux (lumens) for a light source with a given beam angle.

Purpose: It helps lighting designers, engineers, and enthusiasts understand the total light output based on intensity and beam spread.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Lumens — Total luminous flux
• cd — Luminous intensity in candela
• θ — Beam angle in degrees

Explanation: The formula accounts for the angular distribution of light from the source. Narrower beams concentrate the same intensity over smaller areas.

3. Importance of Candela to Lumens Conversion

Details: Understanding this relationship helps in selecting appropriate lighting fixtures and comparing different light sources accurately.

4. Using the Calculator

Tips: Enter the luminous intensity in candela and the beam angle in degrees (default 30°). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between candela and lumens?
A: Candela measures luminous intensity (brightness in a direction), while lumens measure total light output in all directions.

Q2: What's a typical beam angle for spotlights?
A: Spotlights typically have beam angles between 15-45 degrees, while floodlights range from 45-120 degrees.

Q3: How does beam angle affect lumens?
A: For the same candela rating, a wider beam angle produces more total lumens as light is distributed over a larger area.

Q4: What's the conversion for a full 360° light source?
A: For a full sphere (360°), the formula simplifies to Lumens = cd × 4π (about 12.57).

Q5: Why is cosine used in the formula?
A: Cosine accounts for the angular distribution of light intensity following Lambert's cosine law.