The comparison was done using two bulbs of similar brightness: A 60W incandescent and a 12W LED: The 60W incandescent bulb uses 60 kilowatt-hours (kWh) of electricity every 1,000 hours.

We multiply the kilowatts (remembering to divide the number of watts by 1,000) by the hours. Total incandescent energy use: 0.1836x126=23.1 kWh Total LED energy use: 0.031x126=3.9 kWh ...

The incandescent bulb also only converts about 1% to 3% of total energy used to power the bulb into visible light, whereas LED and fluorescent light bulbs convert closer to between 75% and 90% of ...