Bulb LED 4W (470lm) 3-step Dim E14 Useful information about bulbs When buying a new LED bulb, there are some important things to 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 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 an ordinary home, it is recommended that you use a bulb with a CRI value of min. 80CRI. The Kelvin rating, on the other hand, describes how warm the light from 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 chelvin level of approximately 1,500 K, direct sunlight is 5,500 K, while the blue sky reaches 10,000 K.