Utility July 13, 2026 · 8 Min Read

Electricity Cost Calculator – Guide & Formulas

Calculate the electricity cost of any home appliance based on wattage, usage hours, and your local electricity rate.

Estimate the operating costs of your household appliances. Input the appliance power rating, daily runtime, and electricity rate to compute hourly, daily, monthly, and annual utility costs.

Key Takeaway

Use the free Electricity Cost Calculator to calculate the electricity cost of any home appliance based on wattage, usage hours, and your local electricity rate. Get instant results with step-by-step explanations.

How to Use the Electricity Cost Calculator

  1. Enter the appliance wattage (W) or kilowatts (kW) (e.g., a space heater is usually 1500W).
  2. Input the average hours the appliance is turned on per day.
  3. Enter your local electricity tariff in cents/kWh or dollars/kWh (the US national average is around $0.16/kWh).
  4. Instantly view the total electricity consumed in kWh and corresponding operating costs over daily, monthly, and annual periods.

The Formula

Daily Consumption (kWh) = (Wattage * Hours per Day) / 1000 | Cost = Consumption * Electricity Rate * Days

Variable Definitions

  • Wattage: The power rating of the appliance measured in Watts (W)
  • Daily Consumption: The total electrical energy used in one day in Kilowatt-hours (kWh)
  • Electricity Rate: The cost charged by your utility company per Kilowatt-hour ($/kWh)

Sizing the Cost of running a Space Heater

Calculate the monthly cost of running a 1,500-watt space heater for 6 hours a day at an electricity rate of $0.15 per kWh.

  1. Step 1: Compute daily energy usage: (1,500 Watts × 6 hours) / 1000 = 9 kWh per day.
  2. Step 2: Compute monthly energy usage: 9 kWh × 30 days = 270 kWh per month.
  3. Step 3: Compute daily operating cost: 9 kWh × $0.15 = $1.35.
  4. Step 4: Compute monthly operating cost: 270 kWh × $0.15 = $40.50.

Frequently Asked Questions

How do I find my appliance’s wattage?

Wattage is usually printed on a silver rating label on the back or bottom of the appliance, or in the user manual. If only Volts and Amps are listed, multiply them to get Watts (Watts = Volts × Amps).

What are "phantom loads" or "vampire power"?

This is the electricity consumed by appliances while they are switched off but still plugged in (in standby mode). It accounts for up to 10% of an average household’s electricity bill.

Which appliances consume the most electricity?

Heating and cooling (HVAC) systems are by far the largest consumers (approx 45-50%), followed by water heaters (18%), washers and dryers (5%), and refrigerators (4%).