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What is Kelvin Color Temperature?


Use this visual to understand how Kelvin (K) values are related to common names (e.g. Soft White) in reference to CFL light bulbs.


Kelvin Colors by Temperature for Compact Fluorescent Lamps


The following photo was taken by Planet Bulb of three identical desk lamps with the same wattage spiral CFL bulb only in three different colors (2700K, 4100K and 6500K).  Notice that the true life colors match the diagram above. 

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Kelvin Temperature and Color Examples for CFL Light Bulbs


8000k Light Bulb Kelvin Color Example

Northern Sky: 8000K

A clear sky producing a blue color light outside of the range of currently available light bulbs.

6500k Light Bulb Kelvin Color Example

Overcast Sky: 6500K - 7500K

Slightly blue light shines during an overcast sky. You may have see "Daylight" bulbs, which are included at the low end of this Kelvin temperature range.

4100k Light Bulb Kelvin Color Example

Sunlight at Noon: 4000K - 6500K

The whitest natural light occurs when the sun is directly overhead. The closest light bulbs will be in the "Daylight" range on some packaging. You now know that this is the 4000-6500K range for fluorescent bulbs.

2700k Light Bulb Kelvin Color Example

Incandescent and Halogen Bulbs: 2500K - 3500K

Commonly found in lamps and fixtures in your home and office. These bulbs produce light with a yellow tint. CFL bulbs can produce light in this light range (lower K rating).


Candle Light: 2000K

Candles burn a soft yellow light. One lumen is the amount of light produced by a single candle.


Lord Kelvin
1824 - 1907 

The Kelvin scale and the kelvin are named after the British physicist and engineer William Thomson, 1st Baron Kelvin , who wrote of the need for an “absolute thermometric scale”.

The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero (0 K).