Electricity Cost Calculator — appliance running cost

How it works

Electricity is billed by the kilowatt-hour (kWh) — the energy of one kilowatt used for one hour (US EIA). To find an appliance's running cost you need two steps:

Energy (kWh) = watts ÷ 1000 × hours per day × days

Cost = energy (kWh) × price per kWh

An appliance's power draw in watts is on its label or nameplate. Divide by 1,000 to get kilowatts, multiply by how many hours a day it runs and over how many days, and you have the energy in kWh. Multiply that by the rate on your electricity bill — the US average is around $0.17 per kWh, though it varies widely by region and time of day — to get the cost.

The biggest costs come from high-power heating and cooling (space heaters, air conditioners, dryers, ovens) and from devices that run around the clock (refrigerators, always-on electronics). A 40-watt bulb left on all evening costs pennies; a 1,500-watt heater running all day costs dollars. Knowing the kWh lets you compare any two appliances on the same footing.

Worked example

A 1,500-watt space heater, used 8 hours a day for 30 days, at $0.17 per kWh:

• Energy: 1,500 ÷ 1,000 × 8 × 30 = 360 kWh
• Cost: 360 × $0.17 = $61.20

By contrast, EIA's own example — a 40-watt bulb (0.04 kW) for 5 hours — uses just 0.2 kWh, about 3 cents at the same rate.

Frequently asked questions

How do I calculate the cost of running an appliance?

Convert watts to kilowatts (÷ 1,000), multiply by the hours and days of use to get kilowatt-hours, then multiply by your price per kWh. For example, 1,500 W × 8 h × 30 days = 360 kWh, and at $0.17 a kWh that is $61.20.

Where do I find an appliance's wattage?

On the label, nameplate or manual — usually near the power rating. If only volts and amps are listed, multiply them (watts = volts × amps). Many smart plugs and energy monitors also measure it directly.

What is a kilowatt-hour?

It is the amount of energy used by a 1,000-watt device running for one hour. Your electricity meter counts kilowatt-hours, and your bill charges a price for each one.

What is the average price per kWh?

In the United States it averages roughly $0.17 per kWh for residential customers, but it ranges from under $0.11 to over $0.40 depending on the state, provider and season. Use the rate from your own bill for an accurate figure.

Why is my refrigerator's cost high despite low wattage?

Because it runs continuously. A 150-watt fridge cycling 24 hours a day for a month uses about 108 kWh — more than a 1,500-watt appliance used only a few minutes a day. Total energy depends on power and time together.

How can I lower my electricity costs?

Target the big, long-running loads: heat and cool efficiently, run high-wattage appliances less, switch off always-on electronics, and shift use to cheaper off-peak hours if your rate varies by time of day.