Design Seletti Concept LED light bulb for Chameleon Useful information about light bulbs When buying a new LED light bulb, there are some important things you should be aware of. The brightness of an LED bulb is measured in what is called lumen instead of watt. 15W = 140 lumens 25W = 250 lumens 40W = 470 lumens 60W = 800 lumens 75W = 1050 lumens 100W = 1520 lumens In addition, a RA- or CRI-value is also stated on the light bulb. It describes the light"s ability to reproduce colours and is assessed on a scale of 0-100 CRI, where 100 CRI corresponds to daylight. For a typical home, it is recommended to use a light bulb with a CRI value of min. 80CRI. the Kelvin rating, on the other hand, describes how warm the light of the bulb is. 8.500 - 10,000 K = Cool blue 7.000 - 8,500 K = Cool white/blue 4.500 - 7,000 K = Cool white 3.000 - 4,500 K = Neutral white 1.000 - 3,000 K = Warm white In comparison, the light from a candle has a Kelvin degree of approximately 1,500 K, direct sunlight is 5,500 K, while the blue sky reaches 10,000 K. If you want to know more about light bulbs, you can find more information here.