Electricity calculator

Estimate how much an appliance uses and costs to run. Add more appliances to see your whole home.

Your electricity rate

Find this on your bill (total charge ÷ kWh used). It applies to every appliance below.

Choose an appliance

Modern fridges run the compressor about a third of the time.
Check the label or manual, usually on the back or bottom.
%
Share of "on" time it actually draws the power above.
Refrigerator$5.75/month · 38.4 kWh/month

Estimated cost

$5.75
per month
$0.19
per day
$69.03
per year

Energy use

1.26
kWh/day
38.4
kWh/month
460
kWh/year

How we calculate

watts × quantity × duty cycle × hours per day ÷ 1,000 = kWh per day

Then × your price per kWh for cost. Months use 30.44 days and years 365.25 days on average.

About this estimate

It's an estimate. Real use varies with appliance age, settings, room temperature, how often doors are opened, and how you use it. Preset values are typical figures for common household models, so adjust them to match yours.

Standby power isn't included unless you add it as its own appliance. Many devices draw a few watts even when "off".

This isn't your whole bill. Your bill may also include fixed monthly charges, taxes and fees, tiered rates, demand charges, or time-of-use pricing. We use one flat price per kWh.

Power figures are the draw while running. Heating and cooling loads depend heavily on climate and insulation, so treat them as a starting point.

What is an electricity calculator?

An electricity calculator is a free online tool that turns an appliance's power rating and run time into kWh and cost. The calculator helps you identify what a fridge, microwave, TV, heater, or EV charger adds to your bill before it arrives.

How do you calculate energy consumption?

Multiply the appliance's power (in watts) by how many are running, by the share of time it actually draws that power (duty cycle), and by the hours it's on, then divide by 1,000 to get kWh.

Energy consumption formula:

Energy (kWh) = Power (W) × Quantity × Duty cycle × Usage time (hours) ÷ 1,000.

Enter the duty cycle as a decimal—for example, use 0.35 for an appliance that runs 35% of the time. If power is entered in kilowatts, omit the division by 1,000.

Electricity cost formula:

Cost = Energy consumption (kWh) × Electricity rate per kWh.

Example: a 150 W fridge running 35% of the time for 24 hours uses 150 × 0.35 × 24 ÷ 1,000 ≈ 1.26 kWh a day. At $0.15/kWh, that's about $0.19 a day, or roughly $5.75 a month.

What are the functionalities of this calculator?

The electricity calculator was built to be granular and help you get the answers you need in a simple, easy-to-understand interface. It has a set of features and functionalities that we believe you will appreciate:

  • Presets: about 50 household appliances with realistic typical values, plus a custom option.
  • Flexible inputs: power in W or kW, quantity, duty cycle, and usage in hours or minutes per day or hours per week.
  • Duty cycle help: a tap-to-open explanation with quick values for common appliance types.
  • Live results: cost per day, month, and year, and kWh per day, month, and year.
  • Whole-home mode: add as many appliances as you like and get a total plus a ranked breakdown of where the money goes.
  • Safeguards: warnings for impossible hours, a shared rate and currency, and a "Reset to typical values" link.
  • Transparency: the formula is shown on screen, and an "About this estimate" section explains what isn't included, such as taxes, fixed charges, and standby power.