Electricity Cost Calculator

What Does It Actually Cost to Run That Appliance? Find Out in Seconds

Most people have a rough sense that leaving lights on wastes electricity, or that running a space heater all day is expensive. But "expensive" is a vague word until you put a dollar figure on it. Our free electricity cost calculator converts wattage, usage hours, and your local electricity rate into the exact daily, monthly, and annual cost of running any electrical device in your home or business. Whether you're comparing energy-efficient appliances before buying, investigating why your utility bill spiked, or building a case for energy-saving improvements in a commercial facility, this tool gives you the precise numbers that make informed decisions possible.

The calculation takes three inputs you can gather in about sixty seconds: the wattage of the device (usually printed on a label on the appliance or listed in its specifications), the average number of hours per day you run it, and your electricity rate in cents or dollars per kilowatt-hour (found on your utility bill or your provider's website). Enter these three values and the tool immediately returns your cost per day, cost per month, and cost per year.

How Electricity Cost Calculation Works: The Formula Explained

Electric utilities charge you for energy consumption measured in kilowatt-hours (kWh), not watts. A watt is a unit of power—the rate at which a device consumes electricity at any given instant. A kilowatt-hour is a unit of energy—the total amount consumed over time. To calculate cost, you need to convert from watts to kilowatt-hours and then multiply by your rate.

The formula is: Daily Cost = (Watts ÷ 1000) × Hours per Day × Cost per kWh

For example, a 1,500-watt space heater running 6 hours per day at $0.13 per kWh costs: (1,500 ÷ 1,000) × 6 × $0.13 = 1.5 × 6 × $0.13 = $1.17 per day. Multiply that by 30 days and you get $35.10 per month—a meaningful chunk of a household energy budget from a single appliance. Running this calculation for every significant device in your home creates a clear picture of where your electricity bill is actually coming from.

Finding Your Electricity Rate

Your electricity rate—the cost per kilowatt-hour—is the most important input in this calculation, and it varies significantly by location, utility provider, and sometimes by time of day. In the United States, the national average for residential electricity is roughly 12 to 16 cents per kWh, but rates range from below 9 cents in some states to over 30 cents per kWh in Hawaii and parts of New England. International rates vary even more dramatically.

To find your exact rate, look at a recent utility bill—most providers list a rate per kWh either on the bill itself or in an attached usage details section. Alternatively, your provider's website typically publishes their current rate schedules. If you're on a time-of-use (TOU) pricing plan, your rate varies by hour, with higher rates during peak demand periods (typically weekday afternoons and evenings) and lower rates overnight and on weekends. For TOU calculations, use your peak rate as a conservative estimate for devices you run during peak hours, and your off-peak rate for devices you primarily run at night.

Appliance-by-Appliance Energy Cost Breakdown

Running this calculation across the major devices in your home reveals the hierarchy of energy consumption in your household and identifies where efficiency improvements will have the biggest financial impact. Here are typical wattage figures for common household appliances to help you get started.

Heating and Cooling

Central air conditioning systems typically draw 3,000 to 5,000 watts when the compressor is running. Running a 3,500-watt central AC for 8 hours per day at $0.14/kWh costs $3.92 per day or roughly $118 per month. Window air conditioners are smaller but still significant, typically drawing 500 to 1,500 watts. Electric space heaters range from 750 watts for personal units to 1,500 watts for standard room heaters. Heat pumps are far more efficient per unit of heating output than resistive electric heaters, which is why switching from space heaters to a heat pump system often dramatically reduces winter energy bills.

Water Heating

Electric water heaters are often the second or third largest contributor to a home's electricity bill. A typical 4,500-watt water heater operating for an average of 3 to 5 hours per day costs between $0.57 and $0.95 per day at $0.13/kWh, or $17 to $28 per month. Tankless electric water heaters draw much higher wattage (10,000 to 18,000 watts) but only for the brief periods when hot water is actively flowing, which can make them more economical than tank heaters despite their higher instantaneous draw.

Kitchen Appliances

Electric ovens draw approximately 2,000 to 5,000 watts when the heating element is active. A microwave typically draws 600 to 1,200 watts but is used for much shorter durations. A refrigerator is unusual because it runs continuously but cycles on and off—most modern refrigerators consume the equivalent of 100 to 200 watts on average. Dishwashers draw 1,200 to 1,500 watts and the heat-dry cycle often accounts for the majority of the per-load cost.

Entertainment and Electronics

Modern flat-screen TVs are considerably more efficient than older CRT or plasma screens. A 55-inch LED television draws roughly 100 to 150 watts. A gaming console draws 100 to 200 watts while actively running. A desktop computer with monitor might draw 200 to 400 watts depending on the hardware. These devices individually seem inexpensive to run, but a typical household that runs multiple screens, a gaming setup, and an audio system simultaneously for several hours each day accumulates meaningful costs that calculation makes visible.

Building a Home Energy Audit With This Tool

A systematic room-by-room energy audit using this calculator can identify surprising cost centers and prioritize where efficiency investments pay off fastest. The process is straightforward: for each significant device in a room, look up or estimate its wattage, estimate typical daily use hours, and run the calculation. Record the results and add them up. Most people find that two or three high-draw appliances account for a disproportionate share of the total—and that targeted changes to usage patterns for those specific devices produce the most significant bill reductions.

This audit approach is also valuable before purchasing new appliances. Comparing the wattage specifications of a current appliance against a more energy-efficient replacement model—and calculating the annual cost difference—gives you a concrete payback period for the upgrade cost. An appliance that costs $200 more but saves $80 per year in electricity has a straightforward 2.5-year payback period.

No Account Needed, Completely Free

The electricity cost calculator runs entirely within your browser. Nothing you enter—device wattages, usage hours, or your local utility rate—is transmitted to any server. The tool is completely free with no registration required and no usage limits. Run calculations for every appliance in your home if you want, adjust parameters, and compare scenarios until you have a complete picture of where your electricity spending is going.