lamps linked up with all different kelvin temperature colors and the words Kelvin Temperature in the foreground

Shopping for lightbulbs isn’t as simple as just getting the wattage right, and nowhere is that more evident than with LED bulbs. If you’ve bought LED bulbs in the past, you might have seen that the packaging was labeled with a number followed by the letter “K.”

The letter K represents the bulb’s Kelvin temperature. In this article, we explain how understanding this figure can significantly affect the overall appearance of the rooms in your home. 

So, read on to find out how!

Why Is Knowing About Kelvin Temperature Vital When Buying LEDs?

Bulbs with a Kelvin temperature under 3000K produce a warm, yellow light, while bulbs with a Kelvin temperature of more than 5000K create a cold, white light. In a nutshell, it’s crucial to understand Kelvin temperature because it can have an enormous impact on the ambiance and aesthetic of any space.

a modern looking graphic diagram of orange colors to white and bluish on the range, indicating different Kelvin color temperatures in lighting

Have you ever bought some bulbs, only to find out the color output of them don’t match what you currently have in there? This happens to me, even though I’ve been in the lighting industry myself for 10+ years, and built a commercial energy-efficient lighting distribution company. So it gets the best of us!

This can happen for a few reasons:

  • Different lighting technology: The old bulbs might be incandescent or CFL, while the new ones are LED. You got the same Kelvin, but it looks different (this can be normal)
  • Different manufacturers: If you buy different manufacturers’ bulbs, that means the bulbs are made in different factories, which will mean different components and different build processes, often resulting in a different light output.
  • Confusing Packaging: Sometimes, the light bulb packaging doesn’t even make it clear what Kelvin Temperature the bulb is. It’ll say “warm white” or “cool white”, and what does that even mean?
a box of led bulbs that says soft white with lights on in the background

Read on to learn a bit more about how to avoid these pitfalls.

What is Kelvin Temperature?

Kelvin temperature is used as a measure of the color of light. It’s named after the Scottish engineer and esteemed inventor William Thomson Kelvin. Kelvin discovered the concept of absolute zero, the point at which molecular movement ceases. 

From this, he created a scale that measured temperature in terms of hot and cold relative to absolute zero, but this was later converted to a scale that measured color temperature relative to true black. 

The scale starts at absolute zero, the lowest possible color temperature, and goes up to infinity. The lower the Kelvin temperature, the warmer and more yellow the light appears. The higher the Kelvin temperature, the cooler and whiter the light becomes. 

Hanging light bulbs at various distances with a soft amber glow

Generally speaking, LED bulbs with a Kelvin temperature of 3000K or lower produce warm, yellow-hued light, and bulbs with a temperature of 5000K or higher tend to produce a cool, white light. In between these values, LED bulbs will produce a more neutral light color.

Why Is Kelvin Temperature Important When Buying LED Bulbs?

As discussed, Kelvin temperature is a measure of the color of light, and it can hugely affect how a space in your home looks. 

The choice of warm or cool tones will impact the mood and atmosphere of a room, and from an interior design perspective, it’s an often overlooked factor.

Another overlooked factor is ensuring your bulbs match. For example, if you’re replacing one bulb in a chandelier, you’ll need to be sure that it matches the Kelvin temperature of the rest of the bulbs. 

It will not only affect the overall ambiance of the space, but visually it will be something of an eyesore, as the odd bulb out will be highly noticeable. 

Closeup on a homeowner's arms who's swapping an incandescent bulb for a LED light bulb in a hanging ceiling fixture

It’s also well-documented that the color temperature of the light you’re exposed to can impact your health and well-being. Kelvin temperature can affect your body’s circadian rhythm, and if you’re using the wrong bulbs in certain spaces, it can even negatively impact you.

Warmer, lower Kelvin temperature bulbs are great in bedrooms, as you can leave a soft, yellow light on to read without any adverse effect. However, using bright, white light in the same setting can cause issues  getting to sleep.

Of course, in spaces where you need high focus and alertness, a brighter, cooler light can help keep you awake and even improve your motivation.

Are Kelvin Temperature and CRI the Same?

Kelvin temperature has one of the biggest influences on the overall feel of a room, but it’s often confused with another measurement used in lighting—Color Rendering Index (CRI).

CRI measures how accurately colors are rendered under a particular light source and is expressed as a number from 0-100, with higher numbers indicating the most accurate color rendering. For example, a CRI of 100 means the light source accurately reproduces the color of an object as it would appear in natural sunlight.

So, while Kelvin and CRI are both critical factors in how the LED light bulbs you choose affect the visuals in any given room, the two are technically unrelated.

Choosing the Right Kelvin Temperature for Your Space

When selecting LED bulbs, it’s imperative to consider the purpose of the space and the desired mood or room feel you’re going for. As we know, the Kelvin temperature of the lights in a room dramatically impacts this. 

A row of sconces on a row display a range of kelvin temperatures from the bulbs within.

Here are some tips for choosing the right Kelvin temperature for your space:

Considerations for Different Room and Activity Types

  • For spaces where you want a warm and cozy atmosphere, like a bedroom or living room, choose LED bulbs with a Kelvin temperature of 3000K or less – these bulbs produce warm tones that can help create a relaxing and inviting atmosphere, making them ideal for reading, relaxing, or watching TV.
  • LED bulbs with a Kelvin temperature between 3000K and 5000K are great for spaces like hallways, bathrooms, and kitchens as they provide enough brightness without giving the area a sterile feel.
Man installing light bulb in white room smiling against a red ladder
  • For spaces where you’re likely to perform tasks requiring concentration and detailed work levels, look for LED bulbs with a Kelvin temperature of 5000K or higher – these cool tones provide a brighter, more energetic feel, making them better for tasks that require focus and attention.

Additional Tips for Selecting the Right LED Bulb

  • Consider the CRI of an LED bulb in addition to its Kelvin temperature – bulbs with a high CRI rating will ensure that colors are accurately rendered, something crucial for tasks that require a high degree of color accuracy, such as cooking or makeup application.
  • Consider the beam angle of the bulb – a bulb with a wide beam angle provides a more diffused light and is better for ambient lighting. A narrow beam angle gives off a more focused light and is better for task lighting.
  • Consider the size and shape of the LED bulb, as well as its base size to ensure it will fit in your light fixture.
Various types of LED light bulbs transposed above a white background
  • Look for bulbs with a long lifespan and Energy Star certification to save on energy costs and reduce the frequency at which you need to replace them.
  • Factor in the lumens rating – you can still opt for a low Kelvin temperature and a high lumens rating if you need extra brightness but still want a warmer light.

Final Thoughts

By learning just a bit about Kelvin temperature, you can completely transform how any space in your home looks and feels. You can take it from warm and atmospheric with a sub-3000K temperature bulb to a bright, almost natural daylight feel with 5000K+ bulbs. 

This versatility isn’t only good for ambiance—having the proper lighting feel can drastically improve the way you work and live, too.

The suitable light temperature can make falling and staying asleep easier and even improve motivation and overall performance in any tasks you might need to partake in.

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