Electricity Calculator

Use it when your task matches one of these common needs: Estimate appliance energy use. Compare a heater, AC, computer, or light over time. It works best when you already know the measurements, amounts, units, or options the page asks for.

In plain language: The calculator divides watts by 1,000 to get kilowatts, multiplies by hours and days for kWh, then multiplies by the rate per kWh. The examples on the page are there so you can compare your inputs with a worked example before copying the answer.

Watts: the device power draw. One kilowatt is 1,000 watts. Hours per day: how long the device runs on an average day. Days: how many days you want to estimate. Rate per kWh: your electricity price for one kilowatt-hour before any extra bill fees.

Read the headline answer, then check the smaller lines beside it. For everyday tools, those lines usually show the distance, time, cost, units, or setting that made the answer change.

Real bills include taxes, fees, tiered rates, demand charges, standby use, and variable device power draw. Also check the unit, scale, mode, and result limit because small input changes can change the answer.

A kilowatt-hour is energy use. Running a 1,000 watt device for 1 hour uses 1 kWh. Running a 100 watt device for 10 hours also uses 1 kWh.

No. The calculator runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.