How much does it cost to leave your lights on all night?
A “normal” incandescent bulb costs about 0.75cents per hour, and LEDs or CFLs cost only one-sixth of that – so leaving the lights on (either overnight or while you're at work for the day, say both are about 8 hours) costs you roughly 6 cents for a normal light and a bit over 1 cent for modern bulbs.
Does leaving a light on use a lot of electricity?
Despite myths you may have heard, turning your lights on and off doesn't use more electricity than leaving your lights on. Turning off the lights when you aren't in a room is one of the easiest ways to save energy.
How much electricity is wasted by leaving lights on?
Every bulb has a watt rating printed on it. For example, if the rating is 40 watts, and the bulb is on for one hour, it will consume 0.04 kWh, or if it is off for one hour, you will be saving 0.04 kWh.
Is it cheaper to leave a light on or turn it on and off?
In general, the more energy-efficient a lightbulb is, the longer you can leave it on before it is cost effective to turn it off. In addition to turning off your lights manually, you may want to consider using sensors, timers, and other automatic lighting controls.