Enter your bulb's Power (in watts) and select a Lamp Type — or plug in a Custom Luminous Efficacy — and the Watts to Lumens Calculator converts your wattage into Luminous Flux, showing you exactly how bright your light source actually is, plus its Brightness Category and the Luminous Efficacy used in the calculation.
Luminous Flux
--
Luminous Efficacy Used
--
Brightness Category
--
Lumens are calculated by multiplying watts by the luminous efficacy (lm/W) of the lamp type. The formula is: Lumens = Watts × Luminous Efficacy. Different lamp types have different efficacy ratings.
Luminous efficacy measures how efficiently a light source converts electrical power into visible light, expressed in lumens per watt (lm/W). Higher efficacy means more light output per watt consumed, making the lamp more energy efficient.
LED lamps are the most energy efficient, typically producing 80-100 lumens per watt. They're followed by fluorescent tubes (60-100 lm/W), CFL bulbs (50-70 lm/W), halogen (15-25 lm/W), and incandescent bulbs (10-17 lm/W).
Lighting needs vary by room: living rooms typically need 1,500-3,000 lumens, bedrooms 2,000-4,000 lumens, kitchens 5,000-10,000 lumens, and bathrooms 4,000-8,000 lumens. Consider room size and activities performed.
Yes, this calculator works for all common lamp types including LED, CFL, halogen, incandescent, and fluorescent tubes. You can also enter a custom luminous efficacy value for specialty lighting.
Watts measure electrical power consumption, while lumens measure light output or brightness. Two bulbs with the same wattage can produce different amounts of light depending on their efficiency (luminous efficacy).