Lumens to Candelas Calculator: Convert Lumens to Candelas
Calculate the luminous intensity (in candelas) of a light source by entering its total luminous flux (lumens) and the beam angle.
Understanding Lumens and Candelas
Lumens and candelas are two important units in lighting, but they measure different aspects of light. While lumens measure the total light output of a source, candelas measure the intensity of light in a specific direction. Candelas give a better understanding of how bright a light source is in a given direction, while lumens give a sense of the overall light output.
Why Convert Lumens to Candelas?
The conversion between lumens and candelas is important when you need to understand the intensity of light in a particular direction, especially for directional light sources such as spotlights, flashlights, or vehicle headlights. The formula for converting lumens to candelas depends on the beam angle of the light source. Candelas give a more practical measure of how bright a light will appear from a specific point.
How to Convert Lumens to Candelas
The formula for converting lumens to candelas is:
Candelas = Lumens / (4π × (1 - cos(Beam Angle / 2)))
Where:
- Lumens: Total luminous flux emitted by the light source.
- Beam Angle: The angle at which the light is distributed from the light source.
This formula calculates the luminous intensity in a specific direction based on the total light emitted and the angle over which the light is distributed.
Example Calculation
For a light source with 2000 lumens and a beam angle of 30 degrees, the conversion to candelas would look like:
Candelas = 2000 / (4π × (1 - cos(30° / 2)))
First, we calculate the cosine of the half beam angle:
cos(15°) ≈ 0.9659
Next, we plug it into the formula:
Candelas = 2000 / (4π × (1 - 0.9659)) ≈ 2000 / (4π × 0.0341) ≈ 2000 / 0.4278 ≈ 4673.7 candelas
This gives a luminous intensity of approximately 4673.7 candelas in the direction of the beam.
Understanding Beam Angles
The beam angle plays a crucial role in determining how concentrated or diffuse the light output is. A narrower beam angle results in a higher intensity of light (candelas) because the light is concentrated in a smaller area, while a wider beam angle distributes the light over a larger area, reducing the intensity in any given direction. Common beam angles include:
| Beam Angle (Degrees) | Lighting Application |
|---|---|
| 10° | Spotlights, focused lighting |
| 25° | General spotlighting |
| 40° | Floodlights |
| 60° | General area lighting |
Why is Beam Angle Important?
The beam angle directly affects the distribution of light and its perceived brightness in a given area. Smaller beam angles (e.g., 10° or 25°) result in a more intense, focused light, making them ideal for highlighting specific areas or objects. Wider beam angles (e.g., 60°) spread the light over a larger area, but the intensity is lower in any given direction.
Applications of Candelas
Candelas are used to measure the brightness of directional light sources, such as:
- Spotlights: Focused light used for theatrical, architectural, or landscape lighting.
- Flashlights: Portable light sources with directional beams.
- Headlights: Vehicle lights that illuminate the road ahead.
- Laser pointers: Devices that emit highly directional beams of light.
Frequently Asked Questions
What is the difference between lumens and candelas?
Lumens measure the total light output of a source, while candelas measure the light intensity in a particular direction. Candelas are more useful for directional light sources, as they give a sense of how bright the light will appear in a specific area.
How do I calculate the candelas from lumens?
To calculate the candelas from lumens, you need to know the beam angle. The formula is: Candelas = Lumens / (4π × (1 - cos(Beam Angle / 2))).
Why is the beam angle important when calculating candelas?
The beam angle affects how concentrated the light is. A narrower beam angle means the light is focused in a smaller area, increasing the intensity (candelas). A wider beam angle spreads the light over a larger area, reducing the intensity in any given direction.
What is the best beam angle for my spotlight?
A beam angle of 10° to 25° is ideal for spotlights where you need a focused, high-intensity light. If you want to illuminate a larger area, you can choose a beam angle between 40° and 60°.