LED vs Incandescent Savings Calculator

Savings from switching to LED lighting

For the same amount of light (measured in lumens), an LED bulb draws roughly 10× less power than an incandescent. To find the energy you save per bulb each year, use (W_old − W_LED) × hours/day × 365 / 1000 to get kWh, then multiply by your tariff. Say you swap a 60 W incandescent for a 9 W LED, both putting out around 800 lm. That is 51 W saved. Run them 4 h/day and you get 51 × 4 × 365 / 1000 = 74.5 kWh/year, which works out to about R$ 60/year per bulb at R$ 0.80/kWh. An LED also lasts 25,000-50,000 hours, against roughly 1,000 hours for an incandescent and about 8,000 hours for a compact fluorescent (CFL). In Brazil, Inmetro's PBE programme labels luminous efficacy (lm/W) and sets minimum-performance requirements.

Applications

Cutting a residential power bill, hitting ANEEL Procel/RTQ energy efficiency targets, municipal public lighting concessions, commercial and industrial retrofits, NR-17 ergonomic-visual compliance, relamping projects in hotels and retail, and payback estimates for sustainability committees.

FAQ

Why compare lumens, not watts? Watts tell you how much power something draws; lumens tell you how much light it gives off. A 9 W LED and a 60 W incandescent both put out around 800 lm, so they look equally bright while pulling wildly different amounts of power.

Is LED really worth it given the upfront price? In most cases, yes. A bulb used a few hours a day usually pays for itself in 6-12 months, and the LED outlasts the incandescent it replaces by 25-50×.

What about colour temperature? 2700 K reads as warm white, close to an old incandescent; 4000 K is neutral; 6500 K looks like daylight. Bedrooms and living rooms usually sit at 2700-3000 K, while offices and kitchens tend toward 4000 K.