Estimate monthly and yearly electricity cost for one appliance using the energy number you actually have.
Advanced options
Table of contents
How to use our Appliance Energy Cost Calculator
- Choose What number do you have? to match the label, manual, EnergyGuide label, or meter reading you found.
- Fill in only the visible use details, such as Power (watts), Hours used on a use day (hours), Use days each month (days), or Uses each month.
- Enter Electricity price ($ per kWh) from your electric bill when you can; the default is only a starting estimate.
- Open Advanced options only if you need Number of same appliances, Active time (percent), or Monthly electric bill ($) for bill-share context.
- Check whether Electricity used each month and Watts used in the math look reasonable; a huge value often means amps, watts, hours, or days were mixed up.
Definitions
Watt: A unit for how fast electricity is used while an appliance is running.
Kilowatt-hour (kWh): A unit for the amount of electricity used over time; 1 kWh is 1,000 watts used for 1 hour [2].
Electricity price ($ per kWh): The amount your utility charges for each kWh of electricity.
Active time (percent): The percent of the entered run time when the appliance is actually drawing the entered power.
EnergyGuide energy use (kWh per year): The yearly kWh estimate printed on an appliance EnergyGuide label, which is different from the label's estimated cost [3].
Watts used in the math: The effective watt value after applying Number of same appliances and Active time (percent) in watts-based modes.
Common mistakes and quick fixes
Mistake: Typing the Current (amps) number into Power (watts).
Fix: Choose Volts and amps, then enter Voltage (volts) and Current (amps) separately.
Mistake: Using the EnergyGuide estimated yearly cost in EnergyGuide energy use (kWh per year).
Fix: Enter the kWh per year number from the label, then put your own Electricity price ($ per kWh) in the price field.
Mistake: Entering minutes in Hours used on a use day (hours).
Fix: Convert minutes to hours first; for 30 minutes, enter 0.5.
Mistake: Leaving Active time (percent) at 100 for an appliance that cycles on and off.
Fix: Use a lower Active time (percent) when the appliance only draws the listed power part of the time.
Mistake: Comparing Estimated monthly cost between appliances while using different Electricity price ($ per kWh) values.
Fix: Use the same Electricity price ($ per kWh) for every comparison unless you are testing different rates.
Limitations & Key Assumptions / Boundary Conditions
- Results are estimates. Real cost can change with appliance settings, room temperature, age, maintenance, and how often the appliance cycles on and off.
- The default Electricity price ($ per kWh) is a rough US starting value. Your electric bill is the better source because rates vary by location, plan, season, and fees.
- Watts mode and Volts and amps mode assume the entered power level is typical for the run time you enter. Startup surges and variable-speed operation are not modeled.
- EnergyGuide energy use (kWh per year) mode spreads the yearly kWh evenly across 12 months, so it may not match seasonal use.
- Energy for one use (kWh) mode assumes each use or cycle uses the same amount of energy.
- Share of your monthly electric bill uses only the entered Monthly electric bill ($). It does not separate taxes, fixed service charges, or non-electric charges.
Methodology
How the calculator chooses the math
The calculator uses only the inputs that match the selected What number do you have? mode. Hidden inputs are ignored, so EnergyGuide energy use (kWh per year) mode does not use hours or Active time (percent).
Watts from label
Watts are converted to kilowatts by dividing by 1,000, then multiplied by hours and days [4].
monthly_kwh = (watts * quantity * active_percent / 100 / 1000) * hours_per_day * days_per_month
daily_use_kwh = (watts * quantity * active_percent / 100 / 1000) * hours_per_day
Volts and amps
For single-phase AC, volts times amps gives apparent power (VA). Multiplying by "Power factor (0 to 1)" gives estimated real watts. Use measured or specified power factor; the default 1 assumes unity and may overestimate running watts. For DC, use 1.
monthly_kwh = (volts * amps * power_factor * quantity * active_percent / 100 / 1000) * hours_per_day * days_per_month
daily_use_kwh = (volts * amps * power_factor * quantity * active_percent / 100 / 1000) * hours_per_day
EnergyGuide yearly kWh
When you enter an EnergyGuide yearly kWh value, the calculator treats that number as the yearly energy estimate and divides by 12 for a typical month [2].
yearly_kwh = energy_per_year * quantity
monthly_kwh = yearly_kwh / 12
kWh per use
For a cycle, load, or charging session, the calculator multiplies the energy for one use by the number of uses each month.
monthly_kwh = energy_per_use * uses_per_month * quantity
yearly_kwh = monthly_kwh * 12
Cost and bill share
Cost is energy use multiplied by Electricity price ($ per kWh). The optional bill share is shown only when Monthly electric bill ($) is entered and greater than 0.
monthly_cost = monthly_kwh * electricity_rate
yearly_cost = yearly_kwh * electricity_rate
bill_share_percent = monthly_cost / monthly_bill * 100
Mini-example
A 1,500 watt appliance used 1 hour per day for 30 days at $0.15 per kWh uses 45 kWh in a month.
monthly_kwh = (1500 / 1000) * 1 * 30 = 45
monthly_cost = 45 * 0.15 = 6.75
That gives an Estimated monthly cost of $6.75 and an Estimated yearly cost of $81.00.
Sources
- Estimating Appliance and Home Electronic Energy Use | Department of Energy - Energy
- Measuring electricity - U.S. Energy Information Administration (EIA) - EIA
- How To Use the EnergyGuide Label To Shop for Home Appliances | Consumer Advice - FTC
- Electricity explained - data and statistics - U.S. Energy Information Administration (EIA) - EIA