Color Temperature Revisited

Cool light vs warm light.

Have you ever purchased a new light bulb expecting the same warm, yellow light as the bulb you replaced, only to end up with a much brighter, whiter light instead? Chances are you neglected to consider the bulb’s color temperature before making your purchase. Nothing turns people off from making the switch to LED or fluorescent lamps like accidentally selecting a bulb in the wrong hue, so we figure it’s about time for us to revisit this topic in a new light.

Choosing the Right Color Temperature

As you may have already guessed, color temperature has nothing to do with physical heat. Rather, it describes the warm/cool characteristics of light according to its color, ranging from the orange glow of a candle to the bright blue light of the sun. Measured in degrees Kelvin, the color temperature scale is even backwards from an ambient temperature scale: the lower the color temperature, the warmer (or more orange) the light is; the higher the color temperature, the cooler (or more blue) the light is. Most lights have color temperatures between 2700K and 6500K, and the particular color temperature you need depends on your room and application.


Warm Light (2700K – 3500K)

  • Living Rooms
  • Bedrooms
  • Rooms decorated in earthy tones (reds, oranges, and yellows)

Lights with color temperatures between 2700K-3500K are considered “warm.” Warm light is standard in most homes because it strengthens the reds, oranges, and yellows commonly used in residential color schemes. Warm light is often used in bedrooms or living areas to create a cozy atmosphere since it’s softer and easier on the eyes than bright, cool-toned light. It is also often used for general lighting because people tend to look better in warmer-toned light. If you’ve noticed that more of your flaws show in your bathroom mirror than your bedroom mirror, it’s because many homes have cooler lighting installed in the bathroom.


Cool Light (4000K – 4500K)

  • Kitchens
  • Bathrooms
  • Rooms decorated in airy, fresh hues (blues, greens, whites)

Although warm light is the norm, some people prefer cooler light in their homes. Cool light (4000K-4500K) is more common in homes decorated in blues, greens, whites, or other calm hues that higher color temperatures tend to accentuate. In contrast to warm light, cool light creates an energizing and refreshing mood – the reason many people prefer it in studies or home offices. As mentioned before, cool white light makes imperfections and color variations between objects more apparent. While this may not always be ideal, it is useful for applications like makeup lighting or even general lighting in rooms where cleanliness is imperative. For these reasons, even when cool light isn’t used throughout a home, it typically appears in kitchens and bathrooms.


Full Spectrum (5000K – 6500K)

  • Garages
  • Offices
  • Rooms where productivity is key

Technically speaking, full spectrum light is still classified as cool light, although it is another grade cooler than most lighting used in the home. Meant to simulate the color temperature of a bright sunny day, full spectrum light is a bright, white light that appears almost blue in color. Full spectrum light is often described as being harsh on the eyes, so it is not often used residentially. But when it is, it usually appears in garages or home offices, possibly due to studies that have shown that bright white light may increase productivity. Outside of the home, full spectrum lighting is commonly used in museums, jewelry stores, showcase windows, and hospitals.

Color Temperature and Perception

eyeWhile color temperature is important for creating ambiance in a space, it can also dramatically affect the way your wall paint or furniture appears. Installing warm light in a room decorated in cool-toned colors can cause your room to look faded and lackluster, and the same goes for cool light in a warm-toned color scheme. This happens for the same reason why sometimes you buy something you thought was black in the store only to discover it’s actually navy in natural light: no color is definite because its appearance also depends on the color temperature and overall quality of your lighting, a phenomenon called metamerism. Colors may be even further distorted by secondary characteristics such as brightness or color rendering, the effects of which are detailed further in our post on choosing light for paint colors. Overall, you’ll want to stick to our rules of thumb, but keep in mind that color temperature can have a big impact on the look and feel of your home, so choose wisely!

Do you have warm, cool, or even full spectrum lighting in your home? Which do you prefer and why? Tell us in the comments or give us a shout on FacebookGoogle PlusTwitter, or Pinterest!

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Jessica Banke

Jessica is the Lead Copywriter at 1000Bulbs.com, meaning she spends 40 hours a week illuminating the world on lighting topics from A to Z. Otherwise, she can be found on an outdoor patio listening to live music or at home playing with her miniature Australian Shepherd, Sydney. Check back often for more of her fun and practical lighting articles!

  • Russ

    Hi, I have been left with the task of changing the lighting in our church. It is a very high A frame type of sanctuary with a lot of medium wood. Dark pews with gold fabric. Unfortunately whoever designed it used nothing but spots. 5 years ago someone upgraded the incandescent spots to 6500K CFLs. It is way too blue and is hard on the eyes even though the illumination is still not sufficient. At this point it looks like the only option is to change the kelvin of the bulbs. I tried some 2700k but that was way to yellow… What do you suggest?

    • Will Parsons

      The best recommendation I can make is to try a mid-range temperature of 3500K. If that’s still too yellow, a 4000K bulb should work instead.

  • Ashley Hunter

    It is all dependent on personal preference. You can mix warm and cool lights. If you decided to do that, I would suggest warm lights for overhead lighting, lighting that is meant to cover large portion of the room. Try cool lights, which are brighter, for your bedside table or reading lamps.