Lumens to Watts Converter

How to use

1. 1Pick a direction at the top. Watts to lumens starts from a bulb wattage and returns brightness; Lumens to watts starts from a target brightness and returns the wattage you need.
2. 2Pick the bulb technology you have or want to buy (incandescent, halogen, CFL, or LED). The default luminous efficacy in lumens per watt updates with the selection.
3. 3Type the value into the input box. Decimal points and commas both work.
4. 4Read the headline result with the conversion formula. The Same brightness across bulb types panel shows the matching wattages for every other bulb technology so you can choose a replacement.
5. 5Open the Common bulb equivalence chart to map any traditional incandescent wattage (25, 40, 60, 75, 100, 150 W) to the equivalent LED, CFL, and halogen wattages, or tap a row to load that example into the calculator.
6. 6If your bulb's datasheet lists a different lm/W rating, type it into the Luminous efficacy field. Every result panel and the equivalence chart update instantly.

About this tool

Lumens to Watts Converter turns the brightness number printed on a bulb (lumens, lm) into the electrical power it draws (watts, W), and vice versa, for the four bulb technologies a shopper actually picks between: incandescent, halogen, CFL, and LED. The relationship is linear: lumens equals watts multiplied by luminous efficacy in lumens per watt (lm/W). The tool ships with conservative midpoints from public lighting catalogs and US Department of Energy Lighting Facts data (incandescent 12.6, halogen 16.5, CFL 57, LED 83 lm/W), and every efficacy value is editable so a user with a specific manufacturer datasheet can match the figure on the box. Pick a direction (Watts to lumens or Lumens to watts), pick a bulb technology, and the headline panel returns the converted value with the formula shown underneath for transparency. A second panel shows the wattage each of the other three bulb types would need to produce the same light output as the current input, so you can answer the most common search behind this category, what LED replaces a 60 watt incandescent bulb. A bulb equivalence chart maps the wattages printed on real-world incandescent packaging (25, 40, 60, 75, 100, 150 W) to the ENERGY STAR lumen ranges they were sold for, then derives the halogen, CFL, and LED wattages using the current efficacies so the chart stays in sync with anything you tune. Tap any chart row to load that wattage into the calculator. Useful for shoppers replacing burned-out incandescent bulbs with LED equivalents, ecommerce sellers writing accurate lighting product listings, interior designers sizing room lighting, lighting engineers planning fixtures, electricians explaining brightness to clients, and anyone trying to match the warm output of an old 60 watt bulb without overshooting on glare. All math runs in your browser; nothing is uploaded.

Free to use. Works in your browser. No signup, no login.