Producer PhilipsKoncept This emits 6300lm, which is equivalent to ca. 200-300W. If you find all the different sorts of bulbs confusing, here’s a short review of the most important things that you should be aware of: Today, light intensity is measured in lumen instead of watt. Here’s a rough guide to how they compare: 15W = 140 lumen 25W = 250 lumen 40W = 470 lumen 60W = 800 lumen 75W = 1,050 lumen 100W = 1,520 lumen Bulbs are also classified with an RA or CRI rating. This rating represents how well a bulb’s light reproduces colours on a scale of 0-100 RA. 100 RA is perfect colour reproduction, the same as you would see in natural daylight. For use in the home, look for an RA rating of more than 80. You will also see a kelvin value, measured in degrees. This is the colour of light the bulb emits. A bulb with a kelvin value of 2,700 – 3,000 has a warm light. 4,000-4,500 gives a neutral to cool light that is optimal for a work light. If you need some extra energy in the dark months, look for a kelvin value of 6,000 or higher. If you’d like to know more about bulbs, you can find more information here.