Electricity Cost Calculator

To calculate electricity cost, convert watts to kilowatts, multiply by hours used, then multiply by your price per kilowatt-hour. A 1,000-watt appliance running 5 hours a day uses 5 kWh. At a rate of $0.17/kWh that is $0.85 per day, about $25.50 per month and $310 per year. Change any input above and the answer updates instantly.

The reason this calculator gives a trustworthy number is simple: you enter your own electricity rate. Utility prices in the United States range from under $0.11/kWh in Idaho and Washington to over $0.30/kWh in California and Hawaii. A calculator that hard-codes a single national average can be wrong by 2–3× for your household. By pulling the exact $/kWh figure off your bill, you replace a guess with a personalized, defensible cost you can act on.

Every electricity cost calculation rests on one equation, because utilities bill for energy (kilowatt-hours), not for power (watts):

Breaking it into three moves makes it easy to do in your head:

• Watts to kilowatts. Divide the device's wattage by 1,000. A 1,500 W heater is 1.5 kW. A 60 W bulb is 0.06 kW.
• Kilowatts to kilowatt-hours. Multiply kilowatts by the hours the device runs. 1.5 kW for 8 hours is 12 kWh of energy. This is the same quantity your meter records and the number that appears on your bill.
• Kilowatt-hours to dollars. Multiply kWh by your rate. 12 kWh × $0.17 = $2.04.

The nameplate wattage is usually printed on a label, in the manual, or stamped on the power supply. If your device only lists amps, convert first with the AC amps to watts calculator (Watts = Amps × Volts × power factor), then bring the wattage back here. For a broader breakdown of where your energy goes, the power consumption calculator tallies multiple devices at once.

These fully worked examples show the arithmetic behind common questions people ask this tool.

Example 1 — A 65-inch LED TV (120 W) watched 5 hours a day. Energy = (120 ÷ 1000) × 5 = 0.6 kWh/day. At your rate of $0.17: 0.6 × 0.17 = $0.102/day, roughly $3.06/month and $37 a year. Even at California's $0.32/kWh, that TV costs only about $70 a year — reassuring for anyone worried the television is a budget-buster.

Example 2 — A 1,000 W desktop gaming PC used 4 hours a day. Energy = 1.0 × 4 = 4 kWh/day. Cost = 4 × 0.17 = $0.68/day, about $20.40/month and $248 a year. Doubling the daily hours to 8 doubles the cost — a direct, linear relationship you can exploit to cut bills.

Example 3 — A 15 W Wi-Fi router that never turns off (24 h). Energy = 0.015 × 24 = 0.36 kWh/day. Cost = 0.36 × 0.17 = $0.061/day, about $1.84/month or $22 a year. Small always-on loads are cheap individually but add up: ten such 15 W devices cost $220 a year combined.

Example 4 — A 1,500 W space heater run 6 hours on a cold evening. Energy = 1.5 × 6 = 9 kWh/day. Cost = 9 × 0.17 = $1.53/day. Over a 90-day winter that is about $138 for one heater — see the dedicated space heater cost calculator for seasonal planning.

The value of this calculator lives in the rate box. A tool that assumes "average US electricity is about 17 cents" is only correct for a narrow band of households. Your true marginal cost of electricity depends on several factors that no national figure can capture:

• Your state and utility. Residential rates span roughly $0.10 to $0.44/kWh across US states and territories. Two identical refrigerators in Louisiana and Hawaii can differ by $200 a year in running cost.
• Tiered and time-of-use pricing. Many utilities charge more per kWh above a monthly threshold, or more during peak afternoon hours. Your marginal rate — what the next kWh actually costs — is the number to enter, and it may be higher than your average.
• Delivery and rider charges. Your all-in cost includes generation plus delivery, transmission, and taxes. To get your real blended rate, divide your total monthly bill by the kWh used that month.

How to find your exact rate: take your latest bill, divide the total amount due by the total kilowatt-hours consumed. If your bill was $180 for 1,000 kWh, your all-in rate is $0.18/kWh. Enter that here and every result becomes a figure you could defend to the penny. This is why AI chat answers about "how much does it cost to run X" are unreliable — they cannot know your utility, your tier, or your delivery charges. A calculator you feed your own rate can.

1. Enter the device power in watts. Look on the label, the power brick, or the spec sheet. If only amps are listed, multiply amps × volts (120 V in North America, 230 V in much of the world) or use the amps to watts calculator.
2. Enter hours used per day. Be realistic. A fridge compressor runs about 8 hours of every 24 even though it is "always on"; a microwave might run only 0.25 hours a day.
3. Enter your electricity rate. Use your bill's blended rate (total ÷ kWh). Leave the default only if you truly do not know it.
4. Read the results. The primary number is daily cost; monthly and yearly follow, plus the daily energy in kWh so you can sanity-check against your bill.

To model a device used only part of the year — a heater, an air conditioner, a holiday-lights display — calculate the daily cost here, then multiply by the number of days you actually run it rather than the full 365.

Knowing the cost of each device turns a vague bill into a prioritized to-do list. The biggest savings almost always come from the largest watt × hours products, not from the devices that merely feel wasteful.

Target high-wattage resistive heat first. Space heaters, electric water heaters, clothes dryers, and stoves all convert electricity directly to heat at 1,000–5,000 W. Cutting an hour a day off a 1,500 W heater saves more than unplugging a dozen phone chargers for a year.

Attack always-on phantom loads. Devices in standby — game consoles, set-top boxes, older TVs, chargers left plugged in — can total 50–100 W around the clock, quietly costing $75–$150 a year. A smart power strip that kills standby power pays for itself in months.

Shift flexible loads to off-peak hours if you are on a time-of-use plan. Running the dishwasher, EV charger, or pool pump overnight can cut their effective rate by half. Model both rates in this calculator to see the difference in dollars.

For appliance-specific budgeting over a billing period, switch to the appliance running cost calculator, which adds a "days" input so you can price out a full month or season in one shot.

The table below lists representative wattages and realistic daily run-times for common appliances, with yearly cost computed at $0.17/kWh. Your numbers will differ — plug your own wattage, hours, and rate into the calculator above for a household-specific figure. Use this as a starting map of where the money goes.

Notice that the biggest annual costs come from appliances that combine high wattage with long run-times: refrigerators (moderate watts, always cycling), water heaters, and central air conditioning. A 5 W night-light and a 60 W bulb barely register by comparison, which is why chasing tiny loads rarely moves a bill much.

Accurate cost starts with accurate wattage, and there are four reliable ways to find it before you type a number into the calculator.

Read the nameplate or label. Most appliances carry a rating plate — on the back, bottom, or inside a door — listing watts (W) directly. Power supplies and chargers print their output there too. This is the fastest source when the device runs at a steady load.

Convert from amps. If the label lists only amps (A) and volts (V), multiply them: Watts = Amps × Volts. A device rated 8 A on a 120 V circuit draws about 960 W. For motor-driven AC loads, the true power is lower than amps × volts because of power factor; the AC amps to watts calculator applies it correctly.

Measure with a plug-in meter. An inexpensive watt-meter plugged between the outlet and the device shows real-time watts and accumulated kWh. This is the gold standard for cycling appliances, where the nameplate overstates average draw.

Look it up. Manufacturer spec sheets and energy guides list typical wattage for TVs, refrigerators, and HVAC equipment. Use these as a starting point, then refine with a measurement if the device is a big contributor to your bill. Whichever method you use, feed the running wattage — not the surge or peak — into the calculator for an honest cost.

• Using the surge or peak wattage instead of running wattage. Motors and compressors spike at startup but settle to a lower running draw. Use the running figure for cost; only the inverter or breaker needs the surge number.
• Confusing watts with watt-hours. A 100 W device does not use 100 "units" per hour — it uses 0.1 kWh per hour. Cost depends on energy over time, not instantaneous power.
• Assuming "always on" means 24 hours of full draw. Thermostatically controlled devices (fridges, heaters, AC) cycle. A fridge plugged in 24 hours may only run its compressor 8 hours' worth.
• Entering the wrong rate. Using the generation-only charge instead of your all-in blended rate understates cost by 30–50%. Always divide total bill by total kWh.
• Forgetting seasonal duty. A heater run 90 days a year should be costed on 90 days, not 365.

Avoid these and your estimate will land within a few dollars of what actually shows up on your statement.