What is the Difference Between Kelvin and Lumens in Lighting?

When it comes to purchasing light bulbs, it can be overwhelming to understand the technical terms that are commonly used. Terms like Kelvins, Lumens, and Watts are all important in determining the right bulb for your needs. In this article, we will discuss the difference between Kelvins and Lumens to help you make an informed decision.

Kelvins: The Measurement of Color Temperature

Kelvins, abbreviated as K, are a unit of measurement that determines the color temperature of a light. This measurement has nothing to do with the actual temperature of the bulb, but rather the color of the light produced. A bulb with a lower Kelvin rating will produce a warm yellow or orange light. For example, a candle produces light under 2000K. Standard halogen headlight bulbs usually have a color temperature around 3200K to 4600K, producing a white light but not extremely bright.

As we move up the Kelvin scale, lights become whiter, making the light appear brighter. Drivers often prefer bulbs with a higher Kelvin rating because they seem brighter and make it easier to see at night. Maximum performance headlight bulbs start at around 3900K. Some bulbs have an even higher Kelvin rating, producing a whiter light. At the highest end of the Kelvin scale, bulbs have a blue tone. Xenon HID bulbs, which have become popular in recent years, typically have a high Kelvin rating, appearing extremely bright due to their cooler color temperature.

Styling bulbs with a very cool color temperature are also popular, although they are not always street legal. Halogen styling bulbs have color temperatures up to 5000K. Xenon HID styling bulbs are even further up the Kelvin scale, with some reaching up to 7000K. However, most of these very high Kelvin bulbs are too blue in color to be road legal, so they can only be used for styling purposes.

Lumens: The Measurement of Brightness

Lumens are a unit of measurement that determines the brightness of a bulb. Unlike Kelvins, which only tell you how yellow or blue a bulb appears to be, Lumens give the actual light output of a bulb. This is useful when searching for a brighter bulb. While a bulb with a high Kelvin rating may appear brighter, a bulb with more Lumens is actually brighter.

Halogen headlight bulbs usually have around 3000 Lumens, which is sufficient for most drivers to see at night. Even maximum performance halogen headlight bulbs fall around 3000 Lumens, though a higher Kelvin rating may make them appear brighter. To get a brighter bulb, you would need to switch to Xenon HID headlight bulbs, which typically measure around 5000 Lumens.

Watts: The Measurement of Energy Usage

Before new innovations such as HID bulbs and LED bulbs, most light bulbs were measured in Watts. Watts measure how much energy a bulb uses. However, new bulbs are much more energy efficient. Therefore, a bulb may use fewer Watts but produce more Lumens. A cooler color temperature, measured in Kelvins, can also make a bulb appear brighter. Knowing the number of Lumens produced and the Kelvin rating of a bulb will give you a much better idea of how bright a bulb is compared to measuring the Watts.

Is There Any Correlation Between Lumens and Kelvin?

A common misconception is that cool, blue-toned lights have higher lumen outputs than yellow-toned lights. This is NOT true! The bottom line is that there is no correlation between lumen output and Kelvin temperature.

It is possible to have bulbs with high color temperature and low lumen output. Likewise, it is possible to have bulbs with a low color temperature and high lumen output. No two bulbs are the same, and it is even possible to have two bulbs with the same lumen outputs but vastly different color temperatures.

What Is More Important When Selecting A Bulb?

Both lumens and Kelvin temperature are equally important when selecting a bulb. The choice depends on your individual requirements. For example, if you’re installing the LED under an overhead kitchen cupboard as task lighting, high lumen output is crucial because you need to see what you’re doing.

Similarly, it’s important to have a bulb with a mid-level color temperature around 5,000K to 6,000K. This will allow you to accurately see the colors of your food so you can judge its readiness. The impact of Kelvin color temperature cannot be overlooked, as cool, blue-toned light suppresses the production of melatonin, which regulates sleep-wake cycles.

Choosing the Best Bulb

When searching for the best headlight bulb, take note of both Lumens and Kelvins. A bulb with 3000 Lumens or more will be bright enough for just about every driver. If you want an even brighter bulb, HID headlights are the way to go.

When it comes to Kelvins, anything between roughly 3000K and 5000K should do the job. Within this range, bulbs closer to 5000K will appear whiter and brighter. More than 6000K, and your bulbs will have a bright white-blue glow and may not be street legal.


Understanding the difference between Kelvins and Lumens is important when purchasing light bulbs. Kelvins determine the color temperature of a light, while Lumens determine the brightness. By knowing the number of Lumens produced and the Kelvin rating of a bulb, you can choose the best bulb for your needs.

Remember that there is no correlation between lumen output and Kelvin temperature, and both parameters are equally important when selecting a bulb. With the oversaturation of the LED market, it’s possible to find bulbs that fit your exact lumen output and Kelvin color temperature requirements without having to make sacrifices.