Estimate appliance electricity use and cost from watts, hours of use, kWh per cycle, or annual EnergyGuide consumption. See daily, monthly, and yearly kWh and cost.
Electricity Calculator
Choose how you know your appliance's energy use, enter your own electricity rate, and press Calculate.
$/ kWh
Enter the rate from your own utility bill. This calculator never assumes a national average price for you.
Advanced: Include Standby Power
Only use this if you know the device's actual standby draw, such as from a plug-in electricity monitor or manufacturer specification. Leave both fields blank to skip standby entirely.
Standby hours are applied every day of the week, separate from the active days/hours above. Active hours plus standby hours cannot exceed 24 in a day.
Use this mode for dishwasher or washing-machine cycles, dryer loads, EV charging sessions, or any device rated in energy per use rather than watts.
kWh
$/ kWh
Use the estimated annual kWh from an appliance's FTC EnergyGuide label along with your own electricity rate for a more personally relevant simple cost estimate than the label's national-average figure.
kWh/yr
$/ kWh
Add each device's watts, quantity, hours per day, and days per week. Up to 20 appliances. Results rank your devices by annual kWh, since wattage alone does not determine the largest energy user.
$/ kWh
This is a simple energy-cost estimate: energy used × your entered rate. A real utility bill can also include fixed charges, tiered or time-of-use pricing, taxes, fees, and other items this estimate does not include.
Electricity use is usually measured in kilowatt-hours, or kWh. The U.S. Energy Information Administration's guide, Measuring Electricity, explains the distinction between power and energy: watts and kilowatts measure power, while watt-hours and kilowatt-hours measure energy used over time.
One kilowatt equals 1,000 watts. One kilowatt-hour is the energy produced or consumed when one kilowatt of power is used for one hour. The basic appliance formula is:
kWh = (watts ÷ 1,000) × hours used
Visual: Watts → Kilowatts → kWh
A 1,500-watt heater divided by 1,000 is 1.5 kW. Running for 4 hours, that is 1.5 kW × 4 h = 6 kWh.
Converting watts to kilowatt-hours, step by step
Step
Calculation
Result
Convert watts to kilowatts
1,500 W ÷ 1,000
1.5 kW
Convert kilowatts to kWh over 4 hours
1.5 kW × 4 h
6 kWh
What Is the Difference Between Watts and kWh?
This distinction causes a lot of confusion. A watt measures the rate at which a device uses power, the same way speed measures a rate of travel. A kilowatt-hour measures energy accumulated over time, the way miles measure distance traveled. Think of watts as how fast electricity is being used, and kWh as how much electricity has accumulated over a period.
A 1,000-watt device running for one hour uses 1 kWh. The same device running for two hours uses 2 kWh. The power level did not change, but the accumulated energy doubled because the time doubled.
Visual: Power vs. Energy
Watts and kilowatts describe a rate. Kilowatt-hours describe energy accumulated over time. You need both power and time to find energy.
Power compared with energy
Measurement
What It Represents
Watts / kilowatts
Rate of using electricity at a given moment
Kilowatt-hours
Energy used, accumulated over a period of time
How Do I Calculate the Cost to Run an Appliance?
First calculate kWh, then multiply by your electricity rate:
Cost = kWh × electricity rate
Example
Suppose a 1,500-watt heater runs for 4 hours. Convert: 1,500 ÷ 1,000 = 1.5 kW. Energy: 1.5 × 4 = 6 kWh. If electricity costs $0.16 per kWh, then 6 × $0.16 = $0.96.
So the simple electricity charge for those four hours is approximately 96 cents.
How Much Does a 1,500-Watt Heater Cost to Run?
The answer depends on how many hours it runs and your electricity rate. At $0.16 per kWh, one hour is 1.5 kWh × $0.16 = $0.24. Four hours is $0.96. Eight hours is $1.92.
That does not mean every heater continuously consumes its nameplate wattage during every minute it is turned on. Some thermostatically controlled appliances cycle on and off. The calculator above provides a planning estimate based on the power and use you enter.
How Much Does an Appliance Cost Per Month?
Monthly cost should be based on your actual usage pattern. Suppose a device uses 2 kWh per day, seven days per week. Weekly: 14 kWh. Annual: 14 × 52 = 728 kWh. Average month: 728 ÷ 12 ≈ 60.67 kWh. At $0.16 per kWh, that is about $9.71 in average monthly energy cost.
CalculateThisWay labels this Average Monthly Cost rather than implying every calendar month has exactly the same number of days.
Visual: Daily → Weekly → Average Monthly → Annual
Daily use is multiplied by days per week for a weekly total, then by 52 for an annual total. Average monthly use is the annual total divided by 12, since calendar months are not identical.
How daily use becomes weekly, average monthly, and annual totals
Period
How It Is Calculated
Daily
Power (kW) × hours used that day
Weekly
Daily kWh × days used per week
Annual
Weekly kWh × 52
Average Monthly
Annual kWh ÷ 12
How Much Does an Appliance Cost Per Year?
Annual energy is weekly kWh × 52. Multiply that by your electricity rate for annual cost. This can make small daily energy amounts easier to understand: a difference of 0.5 kWh per day becomes approximately 182.5 kWh over a 365-day year when the device is used every day, which is about $29.20 at 16 cents per kWh.
What Is a Kilowatt-Hour?
EIA defines a kilowatt-hour as a measure of energy equal to one kilowatt used for one hour. The power levels can differ while the total energy stays the same. For example: 100 W for 10 hours = 1 kWh. 500 W for 2 hours = 1 kWh. 2,000 W for 30 minutes = 1 kWh.
How Do I Convert Watts to kWh?
You need time. Watts alone cannot tell you kWh. Formula: watts ÷ 1,000 × hours. Example: 800 W for 3 hours. 800 ÷ 1,000 = 0.8 kW. 0.8 × 3 = 2.4 kWh. A "watts to kWh" calculation without a time period is incomplete.
How Do I Calculate kWh Per Day?
Use kW × hours used per day. If the appliance does not operate every day, calculate the days of use separately rather than pretending every day is identical. The calculator above turns hours per day and days per week into weekly, annual, and average monthly energy totals.
Why Nameplate Watts May Not Equal Actual Consumption
An appliance's rated wattage may represent a particular operating condition or maximum draw. Actual electricity use can vary. Examples include refrigerators cycling, air conditioners cycling, variable-speed equipment, computers changing power use, and heaters controlled by thermostats. For the most precise personal measurement, a plug-in electricity monitor or utility data may provide actual consumption. CalculateThisWay describes its wattage-based result as an estimate.
What Is an EnergyGuide Label?
The Federal Trade Commission requires EnergyGuide labels for many categories of household appliances. According to the FTC's guide, How To Use the EnergyGuide Label To Shop for Home Appliances, the yellow label can show an estimated annual energy use, an estimated annual operating cost, and comparisons with similar models.
The FTC explains that the displayed annual operating cost is only an estimate, based on typical use and a national average energy price, and that actual cost depends on how the appliance is used and the local energy price. If you know the label's annual kWh, you can enter that into CalculateThisWay and multiply it by your own electricity rate.
Visual: EnergyGuide Flow
The label's own cost estimate uses an assumed national average price. Using your own rate instead gives a more personally relevant simple estimate.
Turning an EnergyGuide annual kWh figure into your own cost estimate
Step
Value
Annual kWh (from the label)
Example: 500 kWh/year
Your electricity rate
Example: $0.16/kWh
Your simple annual energy estimate
Annual kWh × your rate
How Do I Use Annual EnergyGuide kWh?
Suppose the label says 500 kWh/year and your electricity price is $0.16/kWh. Simple annual energy charge: 500 × 0.16 = $80. Average monthly energy: 500 ÷ 12 ≈ 41.67 kWh. Average monthly energy charge: $80 ÷ 12 ≈ $6.67. This does not recreate the full utility bill. It estimates the energy charge for that amount of electricity.
Why My Utility Bill May Not Equal kWh × Rate
Some electricity bills are more complicated than one flat rate. Possible bill components include fixed customer charges, energy charges, tiered rates, time-of-use rates, fuel adjustments, taxes, local fees, credits, and solar or net-metering adjustments.
The calculator above therefore says estimated energy cost based on entered rate, not your exact utility bill.
How Do I Find My Electricity Rate?
Look at your electricity bill or online utility account. The bill may list a price per kWh, or enough information to estimate an effective rate. If the bill contains both fixed and usage-based charges, dividing the full bill by kWh creates an all-in average rate rather than the pure energy charge. Either can be useful depending on what you are trying to estimate. This calculator lets you choose the rate rather than hardcoding an average.
How Much Electricity Does a Refrigerator Use?
Refrigerators do not normally draw their rated compressor wattage every minute of the day. They cycle. For appliances like refrigerators, the annual kWh on the EnergyGuide label can be more useful than multiplying a nameplate wattage by 24 hours. Use the Annual kWh mode above when that information is available.
How Much Electricity Does a Washing Machine Use?
Some appliances are naturally measured per cycle. If the manufacturer or energy label gives kWh per cycle, use kWh per use × number of cycles. For example, 1.2 kWh per cycle at 5 cycles per week equals 6 kWh/week, or 312 kWh annually.
How Much Does It Cost to Charge an EV?
If you know the electricity delivered during a charging session, multiply kWh by rate. Example: 40 kWh at $0.16 = $6.40. Real EV charging can include charging losses and variable rates, so use the actual metered or estimated kWh if available. This calculator does not estimate driving range.
Which Appliances Use the Most Electricity?
Wattage alone does not answer this. A high-wattage appliance used for a few minutes may use less annual energy than a lower-power device running every day. Energy depends on power × time. That is why the Multiple Appliances mode above ranks appliances by annual kWh rather than wattage alone.
Visual: Multiple Appliances, Ranked by Annual kWh
Hypothetical illustrative example only, not real-world averages. Notice the lower-wattage device used for many hours can outrank a higher-wattage device used briefly.
What Is Standby Power?
Some devices continue drawing electricity while not actively performing their main function. If you know the standby power, the advanced section of the Watts + Hours calculator above can include it. Do not invent standby wattages; use measured or manufacturer-provided values when possible.
How Accurate Is an Electricity Calculator?
Accuracy depends on the inputs. The estimate can differ from reality if wattage varies, the appliance cycles, usage hours differ, the electricity rate changes, or the utility uses tiered or time-of-use rates. For a basic planning estimate, the arithmetic is straightforward. For billing-grade accuracy, use utility or measured consumption data.
Electricity Calculator vs Unit Converter
The Unit Converter can convert many measurement units, but this Electricity Calculator focuses on usage, kWh, time, and cost. It is an energy-use planning calculator, not merely a measurement converter.
The Bottom Line
Electricity cost begins with energy consumption. For a watt-rated appliance: watts ÷ 1,000 × hours = kWh. Then kWh × rate = simple energy cost. CalculateThisWay shows daily, weekly, average monthly, and annual energy and cost while making clear when the result is an estimate rather than an exact utility bill.
Worked Examples
The examples below use the exact same calculation engine as the calculator above. Values are computed live in JavaScript rather than typed in as fixed text, so they will always match what the calculator itself would return for these inputs.
1,500 W Heater
1,500 W, 4 hours/day, 7 days/week, $0.16/kWh.
Watts-to-kWh Conversions
Washing Machine Cycles
1.2 kWh/cycle, 5 cycles/week.
Annual EnergyGuide kWh
500 kWh/year, $0.16/kWh.
Try It Yourself
800 watts, used 3 hours a day, 7 days a week, at $0.16 per kWh.
What is the daily kWh before you even look at cost?
Convert the device's power to kilowatts by dividing watts by 1,000, then multiply by the hours it runs to get kilowatt-hours. Multiply kWh by your electricity rate for an estimated cost. The calculator above performs this automatically.
What is a watt?
A watt is a unit of power. It measures the rate at which a device uses electricity at a given moment, not the total energy used over time.
What is a kilowatt?
A kilowatt equals 1,000 watts. Like watts, kilowatts measure the rate of power use, not accumulated energy.
What is a kWh?
A kilowatt-hour, or kWh, is a unit of energy. The U.S. Energy Information Administration explains that one kWh is the energy of one kilowatt used for one hour. It measures energy accumulated over time, not an instantaneous rate.
How many watts are in a kilowatt?
One kilowatt equals 1,000 watts. To convert watts to kilowatts, divide by 1,000.
How do I convert watts to kWh?
Divide watts by 1,000 to get kilowatts, then multiply by the number of hours the device runs. For example, 800 watts for 3 hours is 0.8 kW times 3 hours, which equals 2.4 kWh.
Can watts be converted to kWh without time?
No. Watts measure power at an instant, while kWh measures energy over a period of time. A watt figure alone cannot produce a kWh result without also knowing how many hours the device was used.
How do I calculate appliance electricity cost?
First calculate kWh (watts divided by 1,000, multiplied by hours used), then multiply that kWh figure by your electricity rate per kWh. The Watts + Hours mode above does this and shows every step.
How much does 1 kWh cost?
It depends entirely on your electricity rate, which varies by utility, location, time of use, and rate plan. Enter your own rate per kWh from a recent bill into the calculator above for a cost that matches your situation.
How do I find my electricity rate?
Check your utility bill or online account for the price per kWh. If the bill mixes a fixed charge with usage charges, dividing the full bill by total kWh gives an all-in average rate rather than the pure energy charge. Either can be useful depending on what you are estimating.
How much does a 1500 watt heater cost per hour?
A 1,500-watt heater uses 1.5 kWh per hour. At $0.16 per kWh that is 1.5 times $0.16, or $0.24 per hour. Enter your own rate above for a figure that matches your electricity price.
How much does a space heater cost per day?
It depends on the heater's wattage, how many hours per day it runs, and your electricity rate. Enter those three values into the Watts + Hours calculator above for a daily, monthly, and annual cost estimate.
How much electricity does a refrigerator use?
Refrigerators cycle on and off rather than drawing their compressor wattage continuously, so multiplying nameplate watts by 24 hours tends to overstate use. If you know the refrigerator's annual kWh from its EnergyGuide label, the Annual kWh mode above gives a more realistic estimate.
How do I use an EnergyGuide label?
The FTC-required EnergyGuide label shows an estimated annual energy use in kWh and an estimated yearly operating cost based on a national average energy price. Entering the label's annual kWh figure into the Annual kWh mode above, along with your own electricity rate, gives a more personally relevant cost estimate.
What does annual kWh mean?
Annual kWh is the total energy a device is estimated to use over one year. It appears on EnergyGuide labels and can be entered directly into the Annual kWh mode above along with your electricity rate.
How do I convert annual kWh to monthly?
Divide annual kWh by 12. Because calendar months do not all have the same number of days, this calculator labels the result Average Monthly Use rather than implying every month is identical.
How much electricity does a TV use?
It depends on the model, screen size, and settings. Check the television's rating label or manual for its wattage, then enter that wattage and your typical daily viewing hours into the Watts + Hours calculator above.
How much electricity does a computer use?
Power draw varies widely between laptops, desktops, and gaming systems. Use the wattage listed on the computer's power supply or manufacturer specifications, along with your typical daily hours of use, in the Watts + Hours calculator above.
How much does a dryer cost to run?
If you know the dryer's wattage and typical run time, use the Watts + Hours mode. If you have a per-cycle kWh figure from the manufacturer or an energy label, the kWh Per Use mode above may be more accurate since dryers are often rated per cycle.
How much does a washing machine cost per cycle?
Enter the machine's kWh per cycle and how many cycles per week you run into the kWh Per Use mode above. For example, 1.2 kWh per cycle at 5 cycles per week works out to 6 kWh per week.
How much does a dishwasher cost per cycle?
If the dishwasher's manual or energy label lists kWh per cycle, enter that figure and your weekly cycle count into the kWh Per Use mode above along with your electricity rate.
How much does EV charging cost?
Multiply the kWh delivered during a charging session by your electricity rate. For example, 40 kWh at $0.16 per kWh is $6.40. Use the kWh Per Use mode above with your metered or estimated session kWh. This calculator does not estimate driving range.
Why is my utility bill higher than this estimate?
This calculator's simple formula is energy used multiplied by your entered rate per kWh. A real bill can also include fixed customer charges, tiered or time-of-use pricing, demand charges, taxes, fees, credits, fuel adjustments, and other utility-specific items that this simple estimate does not include.
What are fixed utility charges?
Fixed customer charges are flat fees a utility bills regardless of how much electricity you use, separate from the per-kWh energy charge. This calculator estimates only the energy charge, not fixed fees.
What are time-of-use rates?
Time-of-use pricing charges a different rate per kWh depending on when electricity is used, such as higher rates during peak afternoon or evening hours. If your utility uses time-of-use pricing, enter the rate that best matches when the appliance runs, or calculate separate estimates for peak and off-peak use.
Does an appliance always use its rated wattage?
Not necessarily. Nameplate wattage can represent a maximum or typical operating condition rather than constant draw. Refrigerators and air conditioners cycle, thermostatically controlled heaters turn on and off, and variable-speed or electronic devices can change their power use. Treat wattage-based results as planning estimates.
What is standby power?
Standby power is electricity some devices continue to draw while not actively performing their main function. If you know a device's standby wattage and how many hours it spends in standby, the optional advanced section of the Watts + Hours calculator can include it. This calculator does not assume or invent a standby value for you.
How do I calculate multiple appliances?
Use the Multiple Appliances mode above to enter watts, quantity, hours per day, and days per week for up to 20 devices at once. It calculates annual kWh and annual cost for each appliance individually, then totals them and ranks them from highest to lowest annual energy use.
Which appliance uses the most electricity?
Wattage alone does not answer this. A high-wattage appliance used briefly can use less annual energy than a lower-wattage device that runs for many hours every day, because energy depends on power multiplied by time. The Multiple Appliances mode ranks your own devices by annual kWh rather than by wattage alone.
Is average monthly electricity the same every month?
No. Calendar months have different numbers of days, so this calculator divides annual use by 12 and labels the result Average Monthly Use or Average Monthly Cost rather than implying every month is identical.
How accurate is an electricity calculator?
Accuracy depends on your inputs. Results can differ from reality if actual wattage varies, the appliance cycles on and off, usage hours change, or your utility uses tiered or time-of-use pricing. For a basic planning estimate the arithmetic is exact; for billing-grade accuracy, use utility data or a plug-in electricity monitor.
Watts + Hours mode converts power to kilowatts (watts ÷ 1,000, or used directly if entered in kilowatts), multiplies by hours used and quantity for daily kWh, then by days per week for weekly kWh, then by 52 for annual kWh, then divides by 12 for average monthly kWh.
Optional standby energy is calculated separately from active-use energy and applied across all 7 days of the week; active hours plus standby hours are validated so they cannot exceed 24 in a single day.
kWh Per Use mode multiplies kWh per use by uses per week and quantity for weekly kWh, then applies the same weekly-to-annual-to-average-monthly conversion.
Annual kWh mode divides the entered annual kWh by 12 for average monthly kWh and by 365 for average daily kWh, and multiplies by your entered rate for cost at each period.
Multiple Appliances mode calculates each row independently using the Watts + Hours formula (without standby), then sums every row for a total and ranks rows from highest to lowest annual kWh.
This calculator never prefills or assumes a national average electricity rate. You must enter the rate per kWh you want to use.
All results are a simple energy-cost estimate (kWh × your entered rate) and do not represent fixed customer charges, tiered or time-of-use pricing, demand charges, taxes, fees, credits, or solar/net-metering adjustments that may appear on an actual utility bill.
This calculator provides a simple planning estimate of appliance electricity use and cost based on the watts, hours, kWh, or annual kWh you enter, multiplied by the electricity rate you enter. It does not hardcode or assume any national average electricity price. Actual electricity bills can differ because of fixed customer charges, tiered or time-of-use pricing, demand charges, taxes, fees, credits, fuel adjustments, solar or net-metering arrangements, and real-world differences between nameplate wattage and actual appliance behavior. For exact billing figures, refer to your utility account.