How to Calculate What an Appliance Costs to Run

Your electricity bill charges for energy in kilowatt-hours (kWh). Once you know an appliance's power and how long it runs, the cost is one multiplication away.

Step 1: Find the power

Look for a label or plate showing watts (W). If it only shows volts and amps, multiply them: watts = volts × amps.

A 2,000 W heater is 2 kW.

Step 2: Energy used

A 2 kW heater running for 3 hours uses 6 kWh.

Step 3: Cost

At $0.17 per kWh, those 3 hours cost 6 × 0.17 = $1.02. Three hours a day for a 30-day month comes to about $30.60.

Everyday examples

At $0.17 per kWh:

• 10 W LED bulb, 5 hours a day: 0.05 kWh a day, about $3.10 a year
• 1,500 W kettle, 15 minutes a day: 0.375 kWh a day, about $23 a year
• 100 W TV, 4 hours a day: 0.4 kWh a day, about $25 a year

Appliances that cycle

Fridges, freezers, air conditioners and heaters with thermostats don't run at full power all the time, so the label wattage overstates their use. Look for a yearly energy figure (kWh per year) on the energy label, or measure with a plug-in energy meter.

Standby power

Devices on standby can each draw a few watts all day, every day. 5 W of standby adds up to about 44 kWh a year.

Check your real rate

Your price per kWh is on your bill. It may change by time of day, and fixed daily charges are separate: they don't change with how much you use.