Design Philips Hue Concept Philips Hue White Ambiance 8W Bluetooth Starter Kit 2 E27 Useful information When buying a new LED lightbulb, there are some things you should be aware of. The strength of an LED lightbulb is measured in lumen rather than watt. 15W = 140 lumen 25W = 250 lumen 40W = 470 lumen 60W = 800 lumen 75W = 1050 lumen 100W = 1520 lumen Furthermore, each lightbulb has an RA or CRI value. This describes the ability of the lightbulb to render colours, and it is measured on a scale from 0-100 CRI, where 100 CRI is the equivalent of natural lighting. For normal homes, we recommend using a lightbulb with an CRI value of at least 80CRI. Degrees Kelvin, on the other hand, describe the warmth of the light. 8,500 – 10,000 K = Cold blue 7,000 – 8,500 K = Cold white/blue 4,500 – 7,000 K = Cold white 3,000 – 4,500 K = Neutral white 1,000 – 3,000 K = Warm white For comparison, candlelight has a degree Kelvin of around 1,500 K, direct sunlight is around 5,500 K, and a blue sky can reach 10,000 K. If you want to know more about lightbulbs, you can read all about them here.