Electricity Cost Calculator

How to use the Electricity Cost Calculator

1. Enter the power use and pick its unit.
2. Enter the hours used per day.
3. Enter the days used per week.
4. Enter the electricity rate.
5. Enter the number of devices.
6. Press Calculate. The result updates automatically as you type.

About the Electricity Cost Calculator

Your utility bills you for kilowatt-hours: one kilowatt of power used for one hour. Multiplying a device's wattage by how long it runs shows exactly where your money goes. The rate is printed on your bill; divide the energy charge by the kWh used if it is not listed directly. Many US households pay between $0.12 and $0.30 per kWh.

Wattage on a label is often the maximum. Devices that cycle on and off, such as refrigerators, air conditioners and electric water heaters, use less on average, so a plug-in energy meter gives the most accurate figure. For things like TVs and computers, also consider standby power, which runs 24 hours a day.

Formula

kWh per day = Watts × Hours ÷ 1,000
Cost = kWh × Rate

A year is taken as 52.18 weeks and a month as one twelfth of a year. Example: a 1,500 W heater used 5 hours a day uses 7.5 kWh, which costs 7.5 × $0.17 = $1.28 per day, or about $38.80 per month.

Example calculation

Using the default values:

• Power use = 1500 W
• Hours used per day = 5 h
• Days used per week = 7 days
• Electricity rate = $0.17 per kWh
• Number of devices = 1

the calculator returns:

• Cost per month: $38.81
• Cost per day of use: $1.28
• Cost per year: $465.69
• Energy per day of use: 7.5 kWh
• Energy per year: 2,739.4 kWh

Frequently asked questions

Last updated: 2026-10-12 · Category: Electrical calculators