Electricity Calculator
$0.00 estimated per month
| Period | Energy (kWh) | Cost |
|---|---|---|
| Per Day | ||
| Per Month | ||
| Per Year |
How Energy Cost Is Calculated
Utilities bill electricity by the kilowatt-hour (kWh) — the energy used by a 1,000-watt load running for one hour. The standard formula is: kWh = (watts × hours used) ÷ 1,000, then cost = kWh × price per kWh. This calculator multiplies your appliance's wattage by how many hours a day (and days a month) it runs, converts that to kilowatt-hours, and applies your utility's per-kWh rate to get daily, monthly, and annual figures. If you're running several identical devices (e.g., a bank of shop lights), the quantity field simply multiplies the wattage before the rest of the math runs.
A Note on the Price Per kWh
Residential electricity rates vary widely by region, provider, and season, and many utilities layer on tiered pricing, time-of-use rates, or delivery/supply charges that don't show up as a flat per-kWh number. The $0.16/kWh default here is only a rough placeholder in that ballpark for illustration — check a recent bill for your actual all-in rate (total charge divided by total kWh used) for an accurate estimate, and re-run the numbers if your utility charges different rates at different times of day.
Nameplate Wattage vs. Real-World Draw
The wattage printed on an appliance's nameplate is usually its maximum draw, not what it consumes on average — a refrigerator's compressor cycles on and off, and a "1500W" space heater on a thermostat rarely runs at full power continuously. For the most accurate estimate, use a plug-in watt meter to measure actual average draw, or check the appliance's EnergyGuide label for its estimated annual kWh. If you're weighing a higher-efficiency replacement against fuel-based alternatives (like a gas heater), the fuel cost calculator can help you compare running costs side by side. For sizing heating or cooling loads in the first place, see the BTU calculator.
Frequently Asked Questions
How do I calculate how much an appliance costs to run?
Multiply the appliance's wattage by the hours it runs per day, divide by 1,000 to convert to kilowatt-hours (kWh), then multiply by your electricity price per kWh. For example, a 1,500W heater run 3 hours a day uses 4.5 kWh/day, which at $0.16/kWh costs about $0.72 per day.
Why does my actual bill not match this estimate?
This calculator assumes constant full-power draw for the hours you enter, but many appliances (refrigerators, heaters, AC units) cycle on and off and rarely run at their nameplate wattage continuously. Utility bills can also include tiered rates, time-of-use pricing, and delivery or service charges beyond a flat per-kWh energy rate, so treat the result as a close estimate rather than an exact figure.