What is Candela?

This is Part 2 of a 4 part series discussing Lumens, Candela, Lux and how those three measurements of light performance impact LED lighting in a marine application for boats: Part 1 – What are Lumens? | Part 2 – What is Candela? | Part 3 – What’s Lux got to do with it? | Part 4 – How Lumens, Candela and Lux work together…

The electromagnetic spectrum is detectable by the human eye. This makes it possible for us to perceive lighting output in different colors and different levels of brightness. Traditionally, general consumers turned to wattage to determine the effectiveness of lighting solutions for their homes, offices, and sporting and other equipment. But a lot has changed in recent decades.

The effectiveness of the LED lights that are powering our cell phones’ backlights and enhancing the quality of our cars’ headlights can be measured based on lux, lumens, and candela. These are three different standards for measuring the lighting power of various products and devices.

Here, we look to answer the question: what is candela?


LED Lights and Candela

LED lights are known for their energy-efficient, cost-saving benefits. They have almost boundless potential in changing how we introduce light in any number of applications. These light-emitting diodes emit visible light when activated by a suitable level of voltage in a semiconductor material. This enables the release of photons, or particles, that represent a quantum of light.

When choosing the right LED lights to power your ceiling lights, outdoor light fixtures, or boat lighting accessories, it’s important to consider candela (symbol: cd). Candela was also once known as candlepower. It is known as the singular International System of Units (SI) unit that is based on human perception.

This is what we care about when we’re looking for advanced lighting power to keep us safe, happy, and productive! LED lights and candela work together to produce a high-powered light output that is concentrated and focused.

Distinguished from lumens — which simply measures the total, visible light output — candela ratings are the SI unit for measuring the brightness of the light source. In measuring the value of light intensity from any singular point in one direction, candela provides the measurement of wavelength-weighted power that is emitted by a light source.


Candela Ratings

The luminous intensity (symbol: lv) of LED lights from any angle is expressed as a “candle” or candela rating. Spotlights and laser pointers have some of the highest candela ratings because the light output exhibits a concentrated and focused effect.

Manufacturers tend to zero in on the luminous intensity of candelas instead of the total light output indicated by lumens. These measurements are important for both societal needs like leisure and security, as well as for environmental efficiency.

However, a discussion on the merits of considering candela when looking for high-powered lights is baseless without speaking to the importance of lumens and lux. And it’s important to look at how these different units function to measure the illuminating power of light.


Candela vs. Lux

Illuminance is considered to be the amount of light on a surface per unit area. This light measurement is calculated by using lux (symbol: lx) in square feet (or meters) with consideration for the area in which the light is emitted.

The distance from the light source — not the light source itself — is also considered. For conversion purposes, one foot-candle is equal to 10.764 lux. So, what does that mean?

Think about how a car’s headlight can turn 1500 lumen into several thousands of candela. This is because the light is focused and only comes out of one part of the light source, and will fall on only one section of the road or surrounding area. Cars, boats, and other vehicles that require navigational aids rely on LED lights. This is especially true about the ones that are equipped with lighting technology to strategically aim the light. This allows more of it to arrive at the intended point of use, thus driving a higher candela rating.

According to Rapid Tables, to calculate candela to lux with distance measured in feet, it’s important to note that the illuminance Ev  in lux (lx) equals 10.76391 times the luminous intensity Iv in candela (cd), divided by the square distance from the light source d2 in square feet.


Candela vs. Lumens

Candela ratings effectively measure the luminous power of visible light, or lumens (symbol: lm). Lumens provide a decisive indication of a light source’s brightness in all directions as perceived by the human eye.

If an 800 lumen light provided light to your guest room at home, you’d note that those 800 lumens would be evenly distributed among the multiple points in that room. If any number of directions were obscured, thus depriving light distribution, the amount of light emitted would drop. And so would the new lumen measurement.

However, when measuring luminous intensity, candela considers any single direction from the light source. So, even if the 800 lumen light bulb was obscured, the rating would be unaffected. That said, we can still rely on lumens to deliver accurate measurements of more brightness as the volume of lumens increases.

But, it’s important to consider the light application before determining if lumens alone can provide important information about the potential light performance of your LED lights.

According to Rapid Tables, to calculate candela to lumens, it’s important to note that the luminous fluxΦv  in lumens (lm) equals the luminous intensity Iv in candela (cd) multiplied by the solid angle Ω in steradians (sr).


Liquid Lumens' Top-Side Underwater Lights deliver high-powered brightness with more lumens

Candela in Your Life

At Liquid Lumens, we know a little something about candela. We have developed the most innovative and technologically-advanced LED lighting in the world.

Our  “Lumen-Boost”™ Technology increases your boat’s standard 12V power supply to deliver next-level performance in both lumen and candela output. Why? Because we care about creating next-level experiences wherever you enjoy life.

Contact us today to learn more about candela ratings and how they affect your elusive search for brighter adventures.

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