Lumens and LED Brightness

Posted by Claire Juozitis on Jun 22nd 2018

In traditional lighting, wattage was the standard measure of brightness. Higher wattage meant a brighter bulb. LED lights are brighter replacements for fluorescent, incandescent, and halogen bulbs, but require far fewer watts to produce the same light. Instead, we measure LED brightness in lumens.

Lumens (lm) are a measure of light output. The higher the lumens, or luminous flux, the brighter the light will appear. For LED lights, standard bulbs start around 800lm but large commercial fixtures such as shoebox street lights or stadium lights can reach 160,000lm per fixture!

Why are LEDs brighter with less wattage?

Without a familiarity of lumens, it can be easy to assume that an LED with fewer watts will be less bright than traditional bulbs with higher wattages; however, that’s not the case. As mentioned above, LED lights require less energy to operate and produce the same or more light than a traditional bulb. By design, LED lights have minimal heat output, making them less hazardous and allowing construction with shatterproof materials. When you power an LED light, more energy is converted to light rather than heat. This is why you will often see wattage equivalency listed in the specifications for LED lights. For example, a standard 16W LED bulb is equivalent to a 100W incandescent bulb in both power and brightness!

What is lighting efficacy?

Another common measurement you will find on spec sheets for LED lights is efficacy. This is not the same as efficiency which refers to the amount of energy used. Efficacy is essentially how you measure the “bang for your buck” when it comes to brightness. It can easily be calculated by dividing lumens/watt. For example, an outdoor LED flood light with 10,000lm and 100W has an efficacy of 100lm/w. Generally, high output LEDs have an efficacy of 100lm/w or more! Some commercial LED lights, such as LED tube lights, can feature efficacies of over 130lm/w.

How does color temperature affect brightness?

Lighting color, or temperature, is measured in Kelvin (K). LED light temperatures usually range from 2700K (warmest) to 6000K (coolest). While a 2700K bulb will cast a cozy, orange glow and a 6000K bulb will emit a crisp, blue light, the brightness will be nearly the same. Changing from 4000K to 5000K will typically only increase brightness by 20-60lm (for the same fixture, of course). This is good to know for living and working spaces: you can customize the lighting color for your desired atmosphere while achieving consistent brightness. If you’d prefer a more intimate atmosphere, you can always choose dimmable LED lights and adjust light levels to your liking.