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What is the difference between Lumens, Kelvins and Watts?

What is the difference between Lumens, Kelvins and Watts?

You will come across three main specifications — Lumens, Kelvin, and Watts — when you shop for LED bulbs. While Watts is one term that most shoppers have heard before, thanks to good old incandescent bulbs, many aren’t sure what Lumens and Kelvin mean. If that holds true for you as well, don’t worry. We’ve got you covered. In this post we’ll give you the lowdown on these three terms.

Sounds good? Let’s dive right in then.


Lumens measure the total light output of a bulb. That is to say, it is a measurement of the brightness of a bulb. A higher lumen reading means the bulb will give a brighter light and vice-versa.

Since lumens tell you how bright a bulb is, you should check lumens — not watts — when buying a new bulb.

Because the brightness of bulbs installed in your home might vary greatly, here are a few general considerations to keep in mind when shopping for LED bulbs:

  • If you want to replace a 100 watt incandescent bulb, go for an LED bulb that gives 1600 lumens or thereabout
  • You should look for an LED bulb with roughly 1100 lumens if you want to replace a 75 watt incandescent bulb
  • You should look for an LED bulb with roughly 800 lumens if you want to replace a 60 watt incandescent bulb
  • You should look for an LED bulb with roughly 450 lumens if you want to replace a 40 watt incandescent bulb


Kelvin is used for denoting the colour temperature of a bulb or any other light source. Higher Kelvin temperatures (3600K to 5000K) are considered cool. On the other hand, lower colour temperatures (2700k to 3000k) are regarded as warm. Since cool light produces higher contrast compared to warm light, it is more suitable for visual tasks. Warm light, by contrast, is frequently used in living spaces as it is more relaxing. For most indoor lighting applications, a colour temperature in the range of 2700K to 3600K is recommended.  That said, for task lighting you may consider cool white LED bulbs. They may also be a better option for home offices or garage.


Watts measure power consumption. In the case of incandescent bulbs, there’s a direct correlation between wattage and brightness. When the former increases, the latter goes up too. However, since LED bulbs are far more energy efficient than its predecessors, you need to consider lumens — not watts—when measuring the total output of a specific bulb.

Frequently Asked Questions

  • Does a higher colour temperature bulb produce more light?

In the case of LED bulbs, Kelvin is one of the most common cited specifications. Many shoppers wrongly think that the higher the Kelvin reading, the brighter the LED bulb.

Kelvin, however, has got nothing to do with the light output. Instead, it denotes the colour of light. It is Lumens, rather than Kelvin, that measures the total light output. So you need to look at an LED bulb’s lumens rating to find out how bright it would be.

For most purposes in a home, 2700K – 3000K is likely to prove sufficient as such bulbs help create a relaxing and warm ambience. However, in some places, especially where you need task lighting, you may want to use LED bulbs with a higher Kelvin reading.

Also, generally speaking, a 5000K LED bulb will appear brighter than a 2700K bulb, but that’s because of the former produces a light that has a higher contrast.

  • How can I calculate how many Lumens to Kelvin?

These two readings are not directly related. So it would be wrong to think on the lines that so many lumens will equal to a certain Kelvin.

  • How bright is 2700 Kelvin or 5000 Kelvin?

Kelvin measures colour temperature, not brightness. For brightness, the correct measurement is lumens. Generally speaking, a 5000K LED bulb will appear brighter compared to a 2700K bulb, but that’s due to higher contrast.