About this tool
The Lumens to Watts Converter is a free, in-browser tool that translates between brightness (lumens) and power (watts) for any bulb technology, so you can find an equivalent-brightness replacement — for example which LED matches an old 60-watt incandescent. It uses typical luminous-efficacy values in lumens per watt: incandescent ≈ 15, halogen ≈ 20, CFL ≈ 60, and LED ≈ 90 lm/W. Enter a value, say whether it is lumens or watts, and pick the source and target bulb types. All calculations run locally in your browser.
The core relationship is lumens = watts × efficacy, and watts = lumens ÷ efficacy. If you enter watts of the source bulb, the tool first finds the brightness (watts × source efficacy), then the equivalent wattage on the target technology (lumens ÷ target efficacy). If you enter lumens directly, it simply divides by each efficacy. Optionally enter a room or surface area in square meters and it also reports illuminance in lux (lumens ÷ area). Because efficacy figures are typical mid-range values, real bulbs vary — always check the lumen rating printed on the package.
As a worked example, a 60-watt incandescent produces about 60 × 15 = 900 lumens, which on an LED at 90 lm/W needs only about 900 ÷ 90 = 10 watts — matching the familiar '60 W = about 9–10 W LED, roughly 800–900 lumens' rule from ENERGY STAR brightness charts. Common reference points are 40 W ≈ 450 lm, 60 W ≈ 800 lm, 75 W ≈ 1,100 lm, and 100 W ≈ 1,600 lm.