Our electricity cost calculator helps you understand how much it costs to run any electrical appliance or device. Enter the wattage, daily usage hours, and your electricity rate to see costs broken down by hour, day, month, and year. Supports both single appliance and multiple appliance calculations to help you identify the biggest energy consumers in your home and find ways to reduce your electric bill.
Input the appliance wattage or select from common presets
Enter how many hours per day you use the appliance
Input your electricity rate (check your utility bill)
See hourly, daily, monthly, and yearly electricity costs
Energy consumption in kilowatt-hours is calculated by multiplying the power in watts by the usage hours and dividing by 1000. The cost is then determined by multiplying kWh by your electricity rate.
kWh = Watts x Hours / 1000; Cost = kWh x Rate
Check your electricity bill for your actual rate per kWh - US average is about $0.16/kWh
Appliances with heating elements (space heaters, ovens, dryers) consume the most electricity
Energy Star rated appliances use 10-50% less energy than standard models
Standby power (phantom load) from electronics can add 5-10% to your electric bill
Running appliances during off-peak hours can save money with time-of-use rate plans
LED bulbs use about 75% less energy than incandescent bulbs for the same brightness
Air conditioning is typically the largest single electricity expense in warm climates
Using a programmable thermostat can reduce heating and cooling costs by 10-15%
Electricity is one of the largest recurring household expenses, with the average US home spending roughly $1,500 per year according to the Energy Information Administration. Yet most people have no idea which appliances drive their electric bill. A central air conditioner running 8 hours a day can cost $150-$250 per month alone, while a modern LED light bulb running 12 hours daily costs only about $1.50 per month. Understanding these per-appliance costs is the key to reducing your electricity bill through targeted efficiency upgrades and usage changes. The calculation is straightforward: multiply the appliance wattage by hours of use to get watt-hours, divide by 1,000 to convert to kilowatt-hours (kWh), then multiply by your electricity rate. The US average electricity rate is approximately $0.16 per kWh, but rates vary widely from $0.10 in states like Louisiana to over $0.30 in Hawaii and California. This electricity cost calculator takes any appliance's wattage, your daily usage hours, and your local electricity rate, then computes the daily, weekly, monthly, and annual operating cost. Use it to compare the running costs of old versus new appliances, estimate the payback period for energy-efficient upgrades, or simply understand where your electricity dollars are going.
Electricity costs depend on three factors:
By calculating the cost of individual appliances, you can identify the biggest energy consumers and find opportunities to save on your electric bill.
Switch to LED lighting, use Energy Star appliances, unplug devices when not in use, and consider time-of-use rate plans.
Smart power strips can eliminate phantom loads, and programmable thermostats can optimize heating and cooling schedules.
To calculate electricity cost, use the formula: Cost = (Watts × Hours ÷ 1000) × Rate. First convert power to energy by multiplying wattage by hours of use, then divide by 1,000 to get kilowatt-hours (kWh), since 1 kWh equals 1,000 watt-hours. Finally multiply the kWh by your electricity rate in dollars per kWh.
For example, a 1,500 W space heater run for 8 hours uses 1,500 × 8 ÷ 1000 = 12 kWh; at $0.15/kWh that costs 12 × 0.15 = $1.80 per day. The kilowatt-hour is the standard billing unit for electrical energy defined by NIST and used by utilities worldwide.
A kilowatt-hour (kWh) is a unit of energy equal to 1,000 watts sustained for one hour, or 3.6 megajoules (MJ) in strict SI terms. The joule (J) is the SI unit of energy, and one watt equals one joule per second, so 1 kWh = 1,000 J/s × 3,600 s = 3,600,000 J. Utilities bill in kWh because the joule is impractically small for household consumption.
Power is measured in watts (W), the SI unit named after James Watt, where W = J/s. According to the BIPM and NIST, the watt and joule are coherent SI derived units. A running 100 W bulb for 10 hours consumes exactly 1 kWh (3.6 MJ) of energy.
If an appliance label lists amperes (A) and volts (V) instead of watts, calculate power with P = V × I, where P is power in watts, V is voltage, and I is current in amps. For a device drawing 5 A on a 120 V circuit, P = 120 × 5 = 600 W.
This relationship, known as the power law and rooted in Ohm's law (V = IR), is documented by HyperPhysics at Georgia State University. For purely resistive loads on AC, this direct multiplication holds; for reactive loads like motors, the true power is P = V × I × power factor. Most US homes use 120 V outlets, while large appliances such as dryers use 240 V circuits.
Running cost depends on wattage and hours of use.
According to ENERGY STAR and the U.S. Energy Information Administration, heating, cooling, and water heating together account for the majority of residential electricity use, making them the highest-impact targets for savings.
This calculator has practical uses beyond simple curiosity.
The Encyclopaedia Britannica notes that electricity demand management is central to both household economics and grid planning, and per-device costing is the foundation of that decision-making.
Your electricity rate is the price you pay per kilowatt-hour, printed on your utility statement, often labeled 'energy charge' or 'price per kWh.' To find your effective rate, divide the total bill by the kWh consumed; this captures supply charges, delivery fees, and taxes that a headline rate may omit.
The U.S. Energy Information Administration reports the national residential average near $0.16/kWh as of 2025, but rates range from about $0.10/kWh in low-cost states to over $0.30/kWh in Hawaii. Many utilities use tiered or time-of-use pricing, so your marginal rate for extra usage may differ. Always use your actual effective rate for the most accurate cost estimates in this calculator.
Standby power, also called phantom load or vampire draw, is the electricity devices consume while switched off or in idle mode. Chargers, TVs, game consoles, and smart speakers draw a few watts continuously to stay ready.
A device pulling 5 W constantly uses 5 × 24 × 365 ÷ 1000 = 43.8 kWh per year, about $7 at $0.16/kWh; multiply across a dozen devices and phantom load can reach 5-10% of a home's bill. According to ENERGY STAR and the U.S. Department of Energy, smart power strips that cut power to idle electronics are an effective countermeasure. Use this calculator with a device's standby wattage to quantify the yearly waste before deciding whether to unplug.
Double-check units and use your effective rate for accuracy.
To scale a daily cost to monthly and annual figures, multiply the daily cost by the number of days: monthly cost = daily cost × 30.4 (the average days per month), and yearly cost = daily cost × 365. For example, a device costing $1.80/day runs to about $54.75/month and $657/year.
This calculator applies these multipliers automatically for hourly, daily, monthly, and yearly totals. Because seasonal appliances like air conditioners and heaters run only part of the year, multiply by the number of actual operating days rather than a full 365 for a realistic annual estimate. The IEC and IEEE define consistent measurement conventions that make these energy calculations comparable across regions and devices.
Data sourced from trusted institutions
All formulas verified against official standards.