Warning Lights


how is the brightness of safety lights measured

There are several different terms that describe how bright a safety light is.

At SWS Warning Lights, we measure the amount of light emitted by a source using Lumens and Candela. Understanding the difference between these units will help you understand how much light you’re actually getting!

That way, you can feel more confident when purchasing your next warning light.

So without further ado, let’s talk about how the brightness of safety lights are measured.


Luminous intensity, which is expressed in candela (cd), measures the quantity of visible light emitted in one specific direction from a light source. In simple terms, candela tells you how far we can be from a light source while still being able to see it.

Candela replaced the standard candle or lamp as a unit of luminous intensity in 1948 after it was concluded a candle wasn’t the most precise light source to measure light intensity.

Candela is an important measurement to keep in mind when choosing warning lights. It communicates how far away you can be while still being able to see the light.

This is incredibly important for vehicles that rely on the attention of pedestrians and other drivers.


Luminous flux or luminous power measures the total amount of light emitted by a source that is visible to the human eye. This measurement is expressed in units known as lumens (l).

Lumens are indicated on light packages in store or in the product descriptions online. You can find our products associated measurements in our online catalogue.

The higher the lumen rating, the “brighter” the light source will appear and vice versa.

It’s important to remember lumens doesn’t consider the spread or divergence of light being emitted by the device.

If you’re trying to figure out how bright a light will be in a specific area, you should consider focusing more on other measurements like candela.

Now that you understand how the brightness of safety lights are measured, let SWS Warning Lights help you find the warning light that works best for you.

Our team of talented engineers and customer service professionals are available to offer on-the-spot solutions that meet your requirements. To learn more about our selection of warning lights give us a call at 1-877-357-0222 or contact us here.

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