Electricity Cost Calculator

Wattage is usually printed directly on an appliance's label, nameplate, or spec sheet — but sometimes it's only listed as amps and volts instead, in which case watts can be found by multiplying the two together (watts = amps × volts). Devices with heating elements or motors — space heaters, hair dryers, window air conditioners, clothes dryers — tend to draw far more power than purely electronic devices like phones or laptops, which is why they usually dominate a home's electricity cost even with relatively modest daily use.

It's also worth knowing that many appliances don't draw their maximum rated wattage continuously. A refrigerator, for example, cycles its compressor on and off throughout the day rather than running at full power constantly, so its actual average draw is often noticeably lower than the peak wattage printed on its label. For a precise reading of what an appliance actually uses, a plug-in watt meter gives a more accurate real-world figure than the label alone.

Many devices draw a small amount of power even when switched off but still plugged in — often called standby or phantom load. Game consoles, TVs, cable boxes, and phone chargers left plugged in year-round are common culprits. Individually, this draw is often just a few watts, but multiplied across a household's chargers, entertainment equipment, and small appliances left plugged in continuously, it can add up to a noticeable and often overlooked chunk of a monthly electricity bill.

Some studies of typical U.S. households have found phantom load can account for somewhere around 5-10% of total residential electricity use — enough that unplugging rarely-used devices, or using a power strip to cut power to a whole entertainment center at once, is a genuinely worthwhile habit for anyone trying to trim their electricity bill without changing how they actually use their home's appliances.

• Watt (W) — a unit of power measuring the rate of energy use; higher wattage means more energy consumed per hour of operation.
• kWh (kilowatt-hour) — the standard billing unit for electricity, equal to 1,000 watts used continuously for one hour.
• Rate (¢/kWh or $/kWh) — what your utility charges per unit of electricity consumed, which varies by provider, region, and sometimes time of day.
• Phantom (standby) load — power drawn by a device that's switched off but still plugged in.

A 1,500W space heater run 3 hours per day, at an electricity rate of $0.16/kWh:

Running that same heater for 6 hours a day instead of 3 exactly doubles the cost to roughly $43.20 a month — a direct, linear relationship that makes it easy to estimate the cost impact of changing usage habits for any single appliance.

• Using max rated wattage instead of typical average draw — many appliances cycle on and off, using meaningfully less power on average than their peak rating.
• Forgetting standby/phantom power — devices left plugged in draw small amounts even when switched "off," adding up across a household.
• Ignoring time-of-use electricity rates — some utilities charge different rates at different times of day, which can change the real cost of running an appliance at a particular hour.