Electricity Calculator
Find the kWh and the cost to run any appliance, or a whole list of them, per day, month and year at your electricity rate.
No watt label? Use amps × volts
Standby power and duty cycle
Standby counts while not running. Duty cycle is the share of time a cycling appliance, such as a refrigerator, draws full power.
Default 18.31¢: U.S. average residential price, July 2026, EIA.
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Space heater at 1,500 W, running 4 hours a day, 30 days a month, uses 180 kWh a month.
That is 20% of the 899 kWh an average U.S. home bought each month in 2022 (EIA).
Energy use
Running it 1 hour less each day saves $8.24 a month and $98.87 a year.
Your calculation
The same steps the calculator runs, with your numbers. Displayed figures are rounded.
- Rate: 18.31 cents ÷ 100 = $0.1831 per kWh.
- Energy while running: 1,500 W × 4 h ÷ 1,000 = 6 kWh per day.
- Energy per month: 6 kWh × 30 days = 180 kWh.
- Cost per month: 180 kWh × $0.1831 = $32.96.
- Cost per year: 180 kWh × 12 × $0.1831 = $395.50.
Typical appliance costs at your rate
Nameplate wattage ranges from a DOE and Virginia Cooperative Extension factsheet, 30 days at $0.1831 per kWh. Hours are examples.
| Appliance | Watts | Hours a day | kWh a month | Cost a month |
|---|---|---|---|---|
| Space heater (portable) | 750 to 1,500 | 4 | 90 to 180 | $16.48 to $32.96 |
| Hair dryer | 1,200 to 1,875 | 0.25 | 9 to 14.06 | $1.65 to $2.57 |
| Microwave oven | 750 to 1,100 | 0.5 | 11.25 to 16.5 | $2.06 to $3.02 |
| Clothes dryer | 1,800 to 5,000 | 1 | 54 to 150 | $9.89 to $27.46 |
| Dishwasher | 1,200 to 2,400 | 1 | 36 to 72 | $6.59 to $13.18 |
| Clothes washer | 350 to 500 | 1 | 10.5 to 15 | $1.92 to $2.75 |
| Water heater (40 gallon) | 4,500 to 5,500 | 3 | 405 to 495 | $74.16 to $90.63 |
| Dehumidifier | 785 | 8 | 188.4 | $34.50 |
| Ceiling fan | 65 to 175 | 8 | 15.6 to 42 | $2.86 to $7.69 |
| Flat screen TV | 120 | 5 | 18 | $3.30 |
| Desktop computer | 120 | 4 | 14.4 | $2.64 |
| Laptop | 50 | 4 | 6 | $1.10 |
Estimates of the energy charge only. Actual bills add fixed customer charges, taxes and fees, and many utilities use tiered or time of use rates.
How the Electricity Calculator Works
This electricity calculator estimates how many kilowatt hours (kWh) an appliance uses and what that energy costs per day, month and year. Enter the power in watts or kilowatts, the hours it runs each day, the days of use and your rate per kWh. The method matches the one the U.S. Department of Energy (DOE) publishes for estimating appliance energy use: find the daily kWh, scale it to the period, then multiply by the utility rate.
Switch to Appliance list to add up to 12 items and see the total monthly cost with each item's share. Optional fields handle appliances without a watt label (amps × volts), standby power and appliances that cycle on and off.
A rate entered in cents is divided by 100 first, so 18.31 cents becomes $0.1831. The calculator keeps full precision through every step and rounds only the displayed figures, so a hand calculation from rounded numbers can differ by a cent.
Watts, Watt Hours and Kilowatt Hours
A watt (W) measures power, the rate at which an appliance draws electricity at a given moment. A watt hour (Wh) measures energy, the amount used over time: a 100 W bulb left on for one hour uses 100 Wh. A kilowatt (kW) is 1,000 watts, and a kilowatt hour is 1,000 watt hours, the unit your utility bills.
To convert watts to kWh, multiply the watts by the hours and divide by 1,000. A 100 W TV running 10 hours uses 1 kWh, a 60 W bulb left on for 24 hours uses 1.44 kWh, and a 2,000 W appliance running 30 minutes uses 1 kWh. Power alone never gives a cost; you always need the running time as well.
Amps to watts
When a label lists amps instead of watts, multiply amps by volts. DOE notes that most appliances in the United States use 120 volts, while larger ones such as clothes dryers and electric cooktops use 240 volts. A space heater drawing 12.5 A at 120 V uses 1,500 W, and an EV charger drawing 30 A at 240 V uses 7,200 W.
Heaters, kettles and incandescent bulbs have a power factor of 1, so volts times amps equals real watts. Motors and compressors run below 1, so volts times amps overstates what the meter records; enter the power factor if you know it, or treat the result as an upper estimate. The Ohm's Law Calculator solves for volts, amps, ohms or watts from any two known values.
How to Calculate Electricity Cost Manually
- Find the wattage. Check the label or nameplate. DOE notes the listed wattage is the maximum power drawn, so an appliance with several settings often uses less.
- Estimate the hours per day. Use your normal routine or keep a short log. For a refrigerator, DOE suggests dividing the time it is plugged in by three to estimate the hours it runs at full wattage.
- Convert to kWh per day. Multiply watts by hours and divide by 1,000.
- Scale to the period. Multiply by the days of use in a month or a year.
- Multiply by your rate. Use the price per kWh from your bill. Divide a rate in cents by 100 to get dollars.
Worked example: a 100 W television
DOE's own example prices a 1,500 W electric kettle used 1 hour a day: 1.5 kWh a day and 547.5 kWh a year, which DOE values at $60.23 using a rate of 11 cents per kWh. At the July 2026 average of 18.31 cents, the same kettle costs 547.5 × $0.1831 = $100.25 a year.
Average Electricity Price per kWh (July 2026)
The U.S. Energy Information Administration (EIA) publishes average retail prices every month in its Electric Power Monthly. The average residential price for July 2026 was 18.31 cents per kWh, 4.9% higher than the 17.45 cents of July 2025. From January through July 2026 the residential average was 18.19 cents. The calculator uses 18.31 cents as its default; replace it with the rate on your bill.
| State | July 2026 (¢/kWh) | July 2025 (¢/kWh) | Cost of 899 kWh |
|---|---|---|---|
| Hawaii | 48.00 | 39.36 | $431.52 |
| California | 33.61 | 32.66 | $302.15 |
| New York | 29.90 | 26.22 | $268.80 |
| Ohio | 19.45 | 17.38 | $174.86 |
| U.S. average | 18.31 | 17.45 | $164.61 |
| Georgia | 16.27 | 15.56 | $146.27 |
| Texas | 15.88 | 15.36 | $142.76 |
| Florida | 15.03 | 15.11 | $135.12 |
| Washington | 14.71 | 13.45 | $132.24 |
| North Dakota | 13.41 | 13.31 | $120.56 |
| Louisiana | 12.72 | 13.12 | $114.35 |
Hawaii had the highest residential price of any state in July 2026 and Louisiana the lowest. Monthly figures are preliminary and seasonal, so your own bill gives a better long run estimate. The last column applies each price to 899 kWh, the average monthly purchase of a U.S. home.
How Much Does It Cost to Run Common Appliances?
The table prices the quick examples at 18.31 cents per kWh. Each row matches the calculator output when you press the example button.
| Appliance | Power and use | kWh a month | Cost a month | Cost a year |
|---|---|---|---|---|
| Space heater | 1,500 W, 4 h a day | 180 | $32.96 | $395.50 |
| Refrigerator | 150 W, 24 h at 33% duty | 35.64 | $6.53 | $78.31 |
| Incandescent bulb | 60 W, 5 h a day | 9 | $1.65 | $19.77 |
| LED bulb | 9 W, 5 h a day | 1.35 | $0.25 | $2.97 |
| Gaming PC | 400 W, 3 h, plus 2 W standby | 37.26 | $6.82 | $81.87 |
| Television | 100 W, 5 h a day | 15 | $2.75 | $32.96 |
| Central AC | 3,500 W, 8 h a day | 840 | $153.80 | $1,845.65 |
| EV charger | 30 A × 240 V, 2 h a day | 432 | $79.10 | $949.19 |
A space heater on its 750 W low setting for the same 4 hours a day costs half as much, $16.48 a month. The FAQ below covers space heaters and EV charging in more detail.
Duty Cycle for Refrigerators, Air Conditioners and Heaters
Appliances controlled by a thermostat do not draw full power the whole time they are switched on. A refrigerator, an air conditioner, a heater with a thermostat and a water heater turn on and off to hold a temperature. The duty cycle is the percentage of time the appliance actually runs at its rated wattage.
DOE's rule of thumb for refrigerators, dividing the plugged in time by three, works out to a duty cycle of about 33%, or 7.92 running hours out of 24. With a duty cycle the calculator multiplies watts × hours × duty: 150 W × 24 h × 33% ÷ 1,000 = 1.188 kWh a day. For a specific model, the EnergyGuide label lists estimated yearly kWh; divide it by 12 for a monthly figure.
A plug in electricity usage monitor measures real cycling use over days or weeks. DOE notes these monitors work with 120 volt devices but not with 240 volt appliances such as dryers, central air conditioners or water heaters.
How to Read an Electric Bill
Your bill shows the kWh used during the billing period, read from the meter, and the charges built on that number. This calculator estimates only the energy portion, so expect your bill to differ. The common parts are:
- Fixed customer charge. A monthly fee that stays the same whether you use 10 kWh or 1,000 kWh.
- Supply or generation charge. The price per kWh for the electricity itself.
- Delivery charge. Transmission and distribution costs, often also billed per kWh.
- Tiered rates. The price per kWh steps up once your use passes a set amount in the billing period.
- Time of use rates. The price depends on the hour, with lower off peak prices. DOE notes that utilities pass savings to customers who shift use to off peak times, such as running a dishwasher late in the evening.
- Taxes and fees. State and local charges added on top.
To find your effective rate, divide the total bill by the kWh used. A $150 bill for 800 kWh works out to 150 ÷ 800 = $0.1875, or 18.75 cents per kWh including fixed charges. That figure gives a closer match to your bill for normal use, but remember that fixed charges do not fall when you use less.
Standby Power and Phantom Loads
Many devices draw power while switched off or idle: TVs, microwaves, game consoles, chargers and computers. Lawrence Berkeley National Laboratory reports that most products draw less than 0.5 W in standby, but a typical American home has so many of them that standby adds up to 5 to 10% of residential electricity use. DOE calls these phantom loads and notes they can be avoided by unplugging the device or switching off a power strip.
Enter standby watts in the optional panel to include them, and the Standby share tile shows the portion of the appliance's energy spent idle. DOE also suggests a quick check: if your smart meter shows hourly use, the reading at 3 AM should be far lower than at 7 PM. If it is not, look for always on loads such as an unused second refrigerator.
How to Lower Your Electricity Bill
- Switch to LED bulbs. DOE reports that residential LEDs, especially ENERGY STAR rated products, use at least 75% less energy and last up to 25 times longer than incandescent lighting. A 9 W LED in place of a 60 W bulb used 5 hours a day saves 7.65 kWh and $1.40 a month, or $16.81 a year per bulb.
- Cut standby loads. DOE recommends an advanced power strip to stop electronics drawing power when not in use.
- Shift use to off peak hours if your utility offers time based rates.
- Set the thermostat back. The DOE Energy Saver Guide says you can save as much as 10% a year on heating and cooling by turning the thermostat back 7 to 10 °F for 8 hours a day.
- Find the biggest loads first. The Appliance list mode ranks every item by monthly cost, and the result card shows what running one appliance an hour less each day saves.
How to Use the Calculator
- Mode. One appliance, or a list for a room or home.
- Power. Watts or kW from the label, or amps × volts.
- Hours per day. Running time; 24 with a duty cycle for always on items.
- Days used. Per month, or per year for seasonal items.
- Rate. Cents or whole currency per kWh from your bill.
Common Mistakes
- Cents typed as dollars. 18.31 in the per kWh unit means $18.31; the calculator warns you.
- Mixing W and kW. 1.5 in watts is 1.5 W, not 1,500 W.
- Nameplate watts for cycling appliances. Add a duty cycle.
- Exact amps × volts for motors. Power factor lowers real watts.
- Hours plugged in instead of hours running.
- Expecting an exact bill match. Fixed charges, taxes and tiers differ.
Frequently Asked Questions
How do you calculate electricity cost?
Multiply the appliance power in watts by the hours it runs each day and divide by 1,000 to get kilowatt hours (kWh) per day. Multiply that by the days of use to get kWh per month, then multiply by your rate per kWh. A 1,500 W space heater used 4 hours a day uses 1,500 × 4 ÷ 1,000 = 6 kWh a day and 180 kWh over 30 days. At 18.31 cents per kWh, the U.S. average residential price for July 2026, that costs 180 × $0.1831 = $32.96 a month. Your bill also adds fixed charges and taxes.
How do I convert watts to kWh?
Watts measure power, the rate of use, and kilowatt hours measure energy, the amount used over time. To convert, multiply watts by hours of use and divide by 1,000: kWh = W × h ÷ 1,000. A 100 W television running 10 hours uses 100 × 10 ÷ 1,000 = 1 kWh. A 60 W bulb left on for 24 hours uses 1.44 kWh, and a 2,000 W appliance running for half an hour uses 1 kWh. If the label lists only amps, multiply amps by volts first to estimate watts, for example 12.5 A × 120 V = 1,500 W.
How much does it cost to run a space heater?
A typical portable electric heater draws 750 to 1,500 watts. At its full 1,500 W it uses 1.5 kWh every hour, which costs about 27 cents an hour at the July 2026 U.S. average residential price of 18.31 cents per kWh. Running it 4 hours a day for 30 days uses 180 kWh and costs $32.96 a month, and 8 hours a day doubles that to $65.92. A heater with a thermostat cycles off once the room is warm, so enter a duty cycle below 100 percent to reflect that.
What is the average electricity price per kWh?
The U.S. Energy Information Administration reported an average residential price of 18.31 cents per kWh for July 2026, up from 17.45 cents in July 2025. The average for January through July 2026 was 18.19 cents. Prices vary widely by state: in July 2026 Hawaii averaged 48.00 cents, California 33.61 cents and New York 29.90 cents, while Louisiana averaged 12.72 cents and North Dakota 13.41 cents. Your own rate is printed on your electric bill and is the best number to enter in the calculator.
How many kWh does an average house use per month?
According to the U.S. Energy Information Administration, the average U.S. residential electricity customer bought 10,791 kWh in 2022, about 899 kWh per month. Louisiana had the highest annual purchases per customer at 14,774 kWh and Hawaii the lowest at 6,178 kWh. At the July 2026 average price of 18.31 cents per kWh, 899 kWh costs about $164.61 before fixed charges and taxes. Use depends on climate, home size and which appliances run on electricity, so compare the figure with the kWh total printed on your own bill.
How much does it cost to charge an electric car at home?
Multiply the charger power by the charging hours to get kWh, then multiply by your rate. A 7.2 kW Level 2 charger, which draws 30 amps at 240 volts, uses 14.4 kWh in 2 hours. At 18.31 cents per kWh that session costs about $2.64, and charging 2 hours every day for 30 days uses 432 kWh, about $79.10 a month. The Department of Energy notes that time based rates suit electric vehicle owners because most vehicles recharge at night, when off peak prices are lower.
Sources & References
- U.S. Energy Information Administration. Electric Power Monthly, Table 5.6.A: Average Price of Electricity to Ultimate Customers by End Use Sector, by State, July 2026 and 2025. Data for July 2026, released September 24, 2026. eia.gov
- U.S. Energy Information Administration. Electric Power Monthly, Table 5.6.B: Average Price of Electricity, Year to Date through July 2026 and 2025. Released September 24, 2026. eia.gov
- U.S. Energy Information Administration. How much electricity does an American home use? FAQ, 2022 data, last updated January 8, 2024. eia.gov
- U.S. Department of Energy, Energy Saver. Estimating Appliance and Home Electronic Energy Use. Dated May 12, 2026; archived copy of July 1, 2026, since the live Energy Saver pages returned "page not found" in October 2026. web.archive.org
- U.S. Department of Energy, Energy Saver. Reducing Electricity Use and Costs. Archived copy of June 25, 2026. web.archive.org
- U.S. Department of Energy, Energy Saver. LED Lighting. Archived copy of June 30, 2026. web.archive.org
- U.S. Department of Energy. Energy Saver: Tips on Saving Money and Energy in Your Home, 2022 (thermostat setback savings). energy.gov
- Grisso, R., Walker, M. A. and Ignosh, J. ENERGY SERIES: Estimating Appliance and Home Electronic Energy Use, Virginia Cooperative Extension BSE-301, February 26, 2020, developed with DOE (typical appliance wattages). pubs.ext.vt.edu
- Lawrence Berkeley National Laboratory. Standby Power. standby.lbl.gov
- U.S. Environmental Protection Agency. Greenhouse Gas Equivalencies Calculator: Calculations and References, electricity used factor of 3.94 × 10⁻⁴ metric tons CO₂ per kWh from eGRID 2022 data, last updated August 4, 2026. epa.gov
Results are estimates of the energy charge based on the values you enter. Actual electric bills include fixed charges, taxes, fees and rate tiers or time of use pricing set by your utility. Every number on this page was recomputed with the same formulas the calculator uses. Reference data checked: October 2026.