Electricity Cost Calculator
Calculate electricity costs for any device. Enter wattage, usage hours, and electricity price to see daily, monthly, and yearly costs.
Key features
- Device wattage input
- Usage hours calculation
- Daily/monthly/yearly cost
- kWh consumption
Guide
Electricity costs money every time an appliance runs, but most people have only a vague sense of what each device costs to operate. Calculating electricity cost from wattage, usage time, and your local rate turns that vague sense into an exact dollar amount. This guide explains the underlying math, how to find the numbers you need, and how to use electricity cost data to reduce your bills. The fundamental unit of electricity consumption is the kilowatt-hour (kWh). One kWh is the energy used by a 1,000-watt appliance running for one hour. Your electricity bill charges you per kWh. The average residential electricity rate in the United States is roughly 16 cents per kWh as of 2026, but rates vary widely by state, utility, and pricing tier. California averages over 30 cents per kWh. Louisiana averages around 12 cents. Check your electricity bill for your exact rate, which is usually listed as a per-kWh charge in the billing details section. The formula for electricity cost is: cost = (wattage times hours of use) divided by 1,000, times the rate per kWh. A 100-watt light bulb running for 10 hours uses 1 kWh. At 16 cents per kWh, that costs 16 cents. A 1,500-watt space heater running for 8 hours uses 12 kWh, costing $1.92 per day or about $57.60 per month if used daily. Finding the wattage of an appliance is the first step. Most appliances list their wattage on a label, usually on the bottom or back of the device. The label might say something like 120V, 5A, 600W. If only voltage and amperage are listed, multiply them to get watts: 120 volts times 5 amps equals 600 watts. Some appliances list a range (e.g., 800-1200W) because their consumption varies with operating mode. Use the higher number for a conservative estimate or the average for a typical use estimate. The product manual and manufacturer's website also list wattage specifications. Common household appliance wattages provide a useful reference. A refrigerator uses 100 to 400 watts but cycles on and off, averaging about 150 watts of continuous equivalent consumption. A central air conditioner uses 2,000 to 5,000 watts. A window AC unit uses 500 to 1,500 watts. A clothes dryer uses 2,000 to 5,000 watts. A washing machine uses 350 to 500 watts. A dishwasher uses 1,200 to 2,400 watts. A microwave uses 600 to 1,200 watts. A laptop computer uses 30 to 70 watts. A desktop computer with monitor uses 150 to 500 watts. A gaming PC with a high-end graphics card can use 300 to 700 watts under load. A LED light bulb uses 7 to 15 watts. An incandescent light bulb uses 40 to 100 watts. An electric oven uses 2,000 to 5,000 watts. A hair dryer uses 1,000 to 1,875 watts. Daily, monthly, and yearly cost calculations follow the same formula scaled to different time periods. If a device uses 200 watts and runs 5 hours per day at 16 cents per kWh: daily cost is (200 times 5) divided by 1,000 times 0.16, which equals $0.16 per day. Monthly cost (assuming 30 days) is $0.16 times 30, which equals $4.80. Yearly cost is $0.16 times 365, which equals $58.40. These small daily amounts add up significantly over a year. An appliance that costs only 50 cents per day costs $182.50 per year. Standby power (phantom load or vampire power) is the electricity consumed by devices when they are plugged in but not actively in use. A television in standby mode, a game console that is off but plugged in, a phone charger with no phone attached, and a cable box in sleep mode all draw power continuously. Individual standby loads are small (1 to 15 watts per device), but a household with 20 or 30 devices on standby can waste 50 to 100 watts constantly. That is 438 to 876 kWh per year, costing $70 to $140 at average rates. Smart power strips that cut power to devices when they enter standby mode can eliminate most phantom loads. Appliances with heating elements are the most expensive to operate. Electric water heaters, space heaters, clothes dryers, electric ovens, and hair dryers all convert electricity directly to heat, which requires large amounts of energy. A typical electric water heater is the second-largest energy consumer in most homes after heating and cooling systems. Switching to a heat pump water heater can cut water heating energy use by 50 to 70 percent because heat pumps move existing heat rather than generating it from scratch. Cooling and heating systems dominate residential electricity bills. Central air conditioning running 8 hours a day at 3,500 watts costs about $4.48 per day or $134 per month at 16 cents per kWh. This single appliance can account for 30 to 50 percent of a summer electricity bill. Setting the thermostat 2 degrees higher reduces cooling costs by roughly 5 to 10 percent. Ceiling fans use only 10 to 75 watts and create a wind chill effect that lets you set the thermostat higher while maintaining comfort. A programmable or smart thermostat that raises the temperature while you are away and cools the house before you return saves 10 to 15 percent on cooling costs according to the US Department of Energy. Electric vehicle charging is a growing part of household electricity consumption. A typical EV battery holds 60 to 100 kWh. Charging at home with a Level 2 charger (7.2 kW) takes 8 to 14 hours for a full charge. The cost at 16 cents per kWh is $9.60 to $16.00 for a full charge. If you drive 12,000 miles per year and your EV gets 3.5 miles per kWh, you use approximately 3,429 kWh per year for driving, costing $549. Compare that to gasoline: 12,000 miles at 30 mpg and $3.50 per gallon costs $1,400 per year. The fuel savings from an EV are substantial but show up as a higher electricity bill. LED lighting versus incandescent lighting demonstrates how wattage directly correlates to cost. Replacing a 60-watt incandescent bulb with a 9-watt LED bulb that produces the same light output reduces that bulb's electricity consumption by 85 percent. If the bulb runs 5 hours per day, the incandescent costs $17.52 per year while the LED costs $2.63 per year. A house with 30 light bulbs saves over $400 per year by switching entirely to LEDs, and LED bulbs last 15,000 to 50,000 hours compared to 1,000 hours for incandescent. The initial cost difference is recovered in energy savings within months. Time-of-use (TOU) electricity pricing charges different rates depending on the time of day. Peak hours (typically afternoon and early evening, such as 2:00 PM to 8:00 PM) cost more than off-peak hours (late night and early morning). If your utility offers TOU pricing, shifting energy-intensive tasks like laundry, dishwashing, and electric vehicle charging to off-peak hours saves money. Peak rates can be two to three times the off-peak rate. The electricity cost calculator helps you compare the cost of running an appliance during peak versus off-peak times by letting you enter different rates. Tiered pricing structures charge more per kWh as your total monthly consumption increases. The first 500 kWh might cost 12 cents each, the next 500 kWh 18 cents each, and anything above 1,000 kWh 25 cents each. Under tiered pricing, reducing your consumption brings a double benefit: you use fewer kWh and you pay less per kWh. Understanding which tier you are in helps you prioritize which energy-saving measures will have the biggest financial impact. Solar panel owners benefit from understanding electricity costs in two directions. Appliances running during peak solar production (midday) effectively use free electricity from the panels. Appliances running at night draw from the grid at full price (unless you have battery storage). Knowing the cost of each appliance helps you decide what to run during solar hours and what to schedule for later. Net metering credits for excess solar production are often valued at a lower rate than the retail rate you pay for grid power, making self-consumption of solar power more valuable than exporting it. Energy-efficient appliance comparisons become straightforward with cost calculations. When shopping for a new refrigerator, two models might cost $800 and $1,000. The cheaper model uses 500 kWh per year, costing $80 annually. The efficient model uses 350 kWh per year, costing $56 annually. The $24 annual savings means the efficient model pays back its $200 premium in about 8 years. For appliances you keep 10 to 20 years, the efficient model wins financially. EnergyGuide labels on appliances sold in the United States show the estimated annual energy consumption in kWh and the estimated annual operating cost. These labels standardize the comparison across brands and models. However, the cost on the label uses a national average electricity rate that may differ from yours. Take the kWh number from the label and multiply by your actual rate for an accurate cost estimate. ENERGY STAR certified appliances meet strict efficiency requirements set by the EPA and typically use 10 to 50 percent less energy than non-certified models. Kill-a-Watt meters and similar plug-in power monitors measure the actual electricity consumption of any device you plug into them. These devices cost $20 to $40 and show real-time wattage, accumulated kWh, and sometimes estimated cost. They are the most accurate way to determine what a specific appliance costs to operate, especially for devices with variable consumption like refrigerators, computers, and entertainment systems. Plug in the monitor, connect your appliance, and let it run for 24 hours to get a representative daily consumption figure. Whole-house energy monitoring systems connect to your electrical panel and track consumption by circuit. These systems show you in real time what your entire home is using, broken down by major circuits. They identify energy waste patterns like a sump pump running more than expected, a furnace fan that never shuts off, or baseline consumption that is higher than it should be. Products like Sense and Emporia Vue cost $100 to $300 and provide smartphone apps with detailed usage graphs. Reducing electricity costs focuses on three strategies: eliminate waste, improve efficiency, and shift timing. Eliminating waste means unplugging unused devices, turning off lights in empty rooms, and fixing issues like a running toilet that causes a well pump to cycle repeatedly. Improving efficiency means replacing old appliances with efficient models, upgrading insulation, sealing air leaks, and switching to LED lighting. Shifting timing means moving high-consumption activities to off-peak hours if your utility offers time-of-use pricing. Commercial and industrial electricity costs follow the same basic formula but add demand charges. Demand charges are based on your peak power draw during a billing period, measured in kilowatts. A factory that uses 500 kW for one hour pays a demand charge based on that 500 kW peak, even if it uses far less the rest of the month. Managing demand by staggering equipment startup times and avoiding simultaneous operation of high-draw equipment reduces these charges. Demand charges can represent 30 to 70 percent of a commercial electricity bill. Cryptocurrency mining uses significant electricity. A single ASIC Bitcoin miner draws 1,200 to 3,400 watts continuously. Running a 3,000-watt miner 24 hours a day at 16 cents per kWh costs $11.52 per day or $4,205 per year. Mining profitability depends entirely on whether the cryptocurrency earned exceeds the electricity cost. Many home miners discover that their electricity bill exceeds their mining revenue, especially in high-rate areas. Home office electricity costs became relevant for many workers after 2020. A typical home office setup includes a laptop or desktop computer (50 to 300 watts), monitor (15 to 80 watts), router (10 to 20 watts), desk lamp (10 to 60 watts), and possibly a space heater or fan (500 to 1,500 watts). Total office consumption ranges from 85 to 1,960 watts depending on equipment and climate control. At the low end, a laptop-based setup running 8 hours a day costs about $4 per month. At the high end with a desktop and space heater, costs can exceed $30 per month. Some employers reimburse home office utility costs, making accurate calculations valuable. Pool and hot tub pumps are major electricity consumers that homeowners often overlook. A pool pump running 8 hours per day at 1,500 watts costs about $57.60 per month. A hot tub heater at 4,000 watts running 4 hours per day costs $76.80 per month. Variable-speed pool pumps reduce consumption by 60 to 80% compared to single-speed models. The pump runs at low speed most of the time and high speed only when needed for cleaning or circulation. The savings pay for the variable-speed pump within 1 to 3 years. Seasonal variation in electricity bills is primarily driven by heating and cooling. Summer bills spike in hot climates due to air conditioning. Winter bills spike in cold climates for homes with electric heat. Spring and fall baseline consumption reveals your non-HVAC electricity use. Comparing your baseline months to your peak months quantifies exactly how much heating and cooling costs. This information guides decisions about insulation upgrades, window replacement, heat pump installation, and thermostat settings. Reading your electricity bill provides data beyond just the total charge. Look for the kWh consumption number, the per-kWh rate (which may be tiered or time-of-use), any demand charges, the billing period (days covered), and comparison data showing your usage versus the previous year or versus similar homes. Many utilities provide online portals with hourly or 15-minute consumption data from smart meters, giving you detailed insight into when and how much electricity you use throughout the day. Watts, kilowatts, megawatts, and gigawatts measure power (the rate of energy use). Watt-hours, kilowatt-hours, and megawatt-hours measure energy (total consumption over time). A 100-watt bulb has 100 watts of power. Running it for 10 hours consumes 1,000 watt-hours (1 kWh) of energy. This distinction matters because your bill charges for energy (kWh), not power (kW). An appliance with high power that runs briefly may cost less than a low-power appliance that runs continuously. Smart home devices create both costs and savings. A smart thermostat uses about 3 watts continuously but saves 10 to 15% on heating and cooling, which could mean $150 or more per year. Smart plugs use 1 to 2 watts each but enable scheduling and remote shutoff that can eliminate standby power from connected devices. Smart LED bulbs use slightly more than standard LEDs due to their wireless radio (about 0.5 watts in standby) but offer scheduling and remote control that can reduce overall lighting costs through better usage habits. The net effect of smart home automation is typically a 5 to 15% reduction in total electricity consumption. Electricity generation sources affect your environmental impact but not your per-kWh cost directly. However, many utilities offer green energy programs where you pay a small premium (1 to 3 cents per kWh) to source your electricity from renewable sources. Some states have deregulated electricity markets where you can choose your electricity supplier, potentially finding lower rates or renewable options. Understanding your per-kWh cost across different suppliers helps you make an informed choice. Calculating the cost of running a home server, network-attached storage (NAS), or always-on computer matters for tech enthusiasts. A NAS drawing 30 watts continuously costs $42 per year at 16 cents per kWh. A home server drawing 150 watts costs $210 per year. A gaming PC left on 24/7 at 200 watts idle costs $280 per year. These always-on devices add up to a meaningful portion of the electricity bill. Configuring sleep modes and wake-on-LAN settings reduces costs while maintaining availability when needed. International electricity rates vary enormously. Germany averages over 35 cents per kWh. Denmark exceeds 40 cents. India averages 8 to 12 cents. Many developing countries subsidize residential electricity. When comparing appliance costs across countries, the electricity rate is a major variable. An appliance that costs $50 per year to run in Louisiana at 12 cents per kWh would cost $150 per year in Germany at 36 cents per kWh. The WebRecast electricity cost calculator takes your appliance wattage, hours of daily use, and electricity rate, then outputs the daily, monthly, and yearly cost. It handles the unit conversion from watts to kilowatts and multiplies by your rate to give you a clear dollar amount. This makes it easy to compare appliances, estimate the impact of usage changes, and identify the biggest contributors to your electricity bill. Enter different scenarios to see how behavior changes, like running the dryer three times per week instead of five, translate into actual dollar savings.
Frequently asked questions
How is cost calculated?
kWh = (watts x hours x days) / 1000, then multiplied by price per kWh.
