Electricity Cost Calculator

The example, appliance by appliance

What a steady load costs to run all the time

Typical wattages and hours in the list

The example at different electricity rates

How to calculate what an appliance costs to run

1. Find the watts. Read the label on the appliance or its power adapter. If it lists amps and volts instead, choose "Amps × volts" and the calculator multiplies them: watts = amps × volts. Or choose a typical appliance from the list and edit the number.
2. Enter hours per day and days of use. Hours per day is how long it actually draws that power. Days can be days per month or days per year: the example runs the air conditioner 90 days per year. A refrigerator cycles on and off, so count the hours its compressor runs (about 8 in the example), not 24.
3. Set the quantity. Watts are multiplied by the quantity. The example has 10 LED bulbs at 10 W each.
4. Enter your rate. The rate starts at $0.1831 per kWh, the U.S. average residential price as of mid-2026. Find yours on your bill: divide the electricity charges by the kWh used, or use the listed price per kWh. Enter it in dollars, so 0.18, not 18.
5. Read the cost per day, month and year. Each row shows cost and kWh for a day it runs, an average month and a year, and the last row adds them up: $33.24 a month and $398.80 a year for the example.

Frequently asked questions

How do I calculate the cost of running an appliance?

Multiply its watts by the hours it runs and divide by 1,000 to get kilowatt-hours (kWh), then multiply by your price per kWh. A space heater (high setting) at 1,500 W for one hour is 1.50 kWh and costs $0.27 at $0.1831 per kWh; run 4 hours a day for 30 days and it is $32.96.

What electricity rate should I use?

Use the price per kWh on your bill. If you do not know it, the calculator starts at $0.1831 per kWh (18.31 cents), the U.S. average residential price as of mid-2026 from the U.S. Energy Information Administration's Electric Power Monthly (a preliminary monthly figure). State averages run from under 15 cents in the cheapest states to over 40 cents in the most expensive, and some plans charge more at peak hours. If your plan has tiers, the price of the last kWh you use is the one that matters for a new appliance.

How do I convert amps to watts?

Watts = amps × volts. A 5 A appliance on a 120 V outlet draws 600 W, and a 20 A load on 240 V draws 4,800 W. This is exact for resistive loads such as heaters; motors and electronics have a power factor below 1, so their real draw can be lower than amps × volts. Nameplate amps are often the maximum, not the typical draw.

Why is my refrigerator not counted for 24 hours?

A refrigerator’s label shows its power while the compressor runs, but the compressor cycles on and off. The example uses 200 W for 8 hours a day, about a third of the day. A plug-in power meter measures the real figure: its kWh reading over a few days is the most accurate input.

What is standby or vampire power?

Many devices draw a little power even when they look off: TVs, game consoles, chargers, set-top boxes, microwaves with clocks. Each is usually small, a watt or a few, but a modern home can have 40 or more such devices running all day. Lawrence Berkeley National Laboratory researchers have informally put standby at roughly 5 to 10 percent of a typical home’s electricity use, though there is no agreed figure. This calculator counts only the hours you enter, so to include standby, add a row with its watts and 24 hours a day ($160.40 a year per 100 W). A power strip you switch off, or a plug-in meter, shows what is really being used.

How many kWh does a home use?

It depends on size, climate and heating. Add up your own appliances in the calculator and compare the monthly kWh with the figure on your bill. The difference is usually heating, cooling and water heating, which are large loads, plus standby power.

Are LED bulbs really cheaper to run?

Yes. At $0.1831 per kWh, a 10 W LED on 5 hours a day costs $3.34 a year, while a 60 W incandescent bulb on the same hours costs $20.05. Heat is the reason: most of an incandescent bulb’s power becomes heat rather than light.

Why do the per-day and per-month costs not multiply exactly?

Each figure is calculated from the exact energy and rounded to the cent once, never from an already rounded figure, so a month can differ from 30 times the daily cost by a cent or two. The total row adds the rounded cost of each row so that every column adds up on paper.

Does this include taxes, fixed charges or time-of-use prices?

No. It multiplies energy by one price per kWh. Your bill may add a fixed monthly charge, taxes, demand charges or different prices by time of day or by tier. For a more exact answer, use your all-in cost per kWh (the whole bill divided by the kWh used) or the rate that applies when the appliance runs.

Is anything I type stored or sent?

No. The calculation runs in your browser and nothing you enter leaves your device.