Understanding the LED Color Spectrum & Lighting Temperatures

A light’s color can have a major impact on how we perceive an environment and how it makes us feel in response. To ensure there is a light for every space, lighting manufacturers produce LEDs that can emit in a large range of color values, or “temperatures.”

In the lighting industry, color temperature is measured using Kelvin (K). Values range from 1000K to 10000K and beyond, though the vast majority of fixtures are clustered around the middle of the spectrum. Color temperatures below 4000K tend to be perceived as warm, or in the yellow, orange and red range. Color temperatures above 5000K are usually perceived as cool, or blueish in hue.

Every type of light, whether it’s incandescent, fluorescent, halogen, sunlight or LED, emits at different parts of the color spectrum. Incandescent lights are known for their dim, warm glow, while fluorescent is cool and intense. One of LED’s advantages is that it can be designed to emit either warm, cool or neutral color temperatures, which makes it a viable choice in most environments.

What color temperature is the best fit for indoors, and what about outdoors?

One of the first things people notice when they enter a room is how the lighting looks. Dark, bright, calming, energizing – a light’s impact typically comes down to its color temperature. Where are you likely to find warm or cool lights, then?

  • Warm LED lights – LED appears warm at around 3000K and below, and at this color temperature, LED lights can stand in for incandescent in most instances. So, it’s common to see warm LEDs in homes, especially in bedrooms, dens and any space where intimacy, coziness and relaxation are important. Warm lights, though, aren’t just limited to residential applications. Warm LEDs are also a good fit in some commercial settings, particularly in smaller boutique stores where lighting volume and intensity isn’t as critical. A warm environment can help people feel welcomed, which can encourage people to remain longer and feel comfortable enough to browse products.
  • Neutral and cool LED lights – At 4000K and above, LED lights appear white or blue-white, so they can be a viable alternative to fluorescent fixtures in commercial settings. In fact, neutral and cool LEDs are quickly becoming a frontline choice for office buildings, manufacturing facilities, large department stores, warehouses, and a whole lot more. On the color temperature spectrum, cooler hues have the opposite effect that warm lights do – they energize and help people focus rather than inspire calm. This is helpful in spaces where people are expected to be productive, so cool LEDs are also appropriate in some residential applications. For example, it’s fairly common to see home offices fitted with cool LEDs, for the same reasons that commercial offices are. It’s also common for homeowners to select cool LEDs for their kitchens and, occasionally, their bathrooms. That’s because cooler hues make a room appear cleaner and more modern. It’s also helpful to have more intense illumination in the kitchen, to cook and clean by.

In the end, the choice between warm and cool fixtures will depend on what materials and colors are already in the space. Warm lighting can bring out the naturally warm tones in wood and fabric, while cool lighting is typically paired with metal.

What is the difference between color temperature and CRI?

Color temperature describes what a particular light looks like, in terms of warm versus cool. The Color Rendering Index (CRI) describes how accurately a particular light presents colors in the environment, ranging on a score from zero to 100. If a fixture has a low CRI score, then objects around the light will not appear to be the color they actually are. A fixture with a high CRI score is the opposite – it renders nearby colors faithfully, as they would be seen under a neutral source of illumination.

Different types of lights vary greatly in their CRI values, and CRI isn’t a critical consideration in every environment. Early LED lights lagged behind other fixtures in CRI, but modern LED lights have closed the gap and there are LEDs available that score 90 or higher.

In the home, LEDs with high CRI values are more important in rooms where accurate color representation is important, such as a closet or perhaps the kitchen. They are also important in commercial settings, museums and galleries, where color rendering is a top priority.

How do lighting manufacturers alter an LED’s color?

Although most lights appear yellow-white, white or blue-white, the exact color composition in each light is much more complex. Daylight appears white, for instance, but it contains every wavelength of light that our eyes are capable of seeing, from red to violet.

Manufactured lights also emit more light at certain spots of the spectrum than others. For instance, a 4000K LED will produce a lot of blue light and moderate amounts of red and green light. The result is a slightly cool, but mostly white appearance. 3000K LEDs, though, emit more red, yellow and green tones, while producing less blue. The result is warmer.

To achieve different looks with the same LED technology, manufacturers add a phosphor to each LED diode. Phosphors are materials that emit light when they are exposed to a form of radiant energy (visible or not). This phenomenon is leveraged in many forms of lighting, including fluorescent lighting, where all of the illumination comes from phosphor luminescence. Neon lights also produce a range of colors using phosphors.

In LED fixtures, phosphors can be used to balance out the naturally cooler tones that the diodes produce, making for a neutral or warmer light. Further, phosphors are also used to produce LEDs that cover the entire visible spectrum, like red, pink, green and yellow.

LED lighting was once limited in the colors it could produce, but that’s no longer the case. Modern LED fixtures can emit all over the color temperature spectrum, from warm to neutral to cool, and render environmental colors with excellent accuracy and unmatched longevity.