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Everyday Calculators

Appliance Wattage Calculator

Use this appliance wattage calculator to estimate what a device costs to run from its wattage and daily use.

Reviewed May 25, 2026EstimateFormula shown

Quick answer

Appliance Wattage Calculator: what it calculates

Appliance Wattage Calculator calculates appliance energy cost from watts, quantity and hours per day. The core method is kWh = watts x quantity x hours / 1000; cost = kWh x electricity rate.

ResultAppliance energy cost
InputsWatts, Quantity, Hours per day, Days per month, Electricity rate
FormulaAppliance wattage formula

Live calculator

Appliance wattage

Monthly energy use72 kWh

2.4 kWh per day.

Monthly cost$12.96

At 18 cents per kWh.

Annual cost$155.52

Monthly cost multiplied by 12.

Wattage is power, kWh is energy

Watts show how much power an appliance draws while running. Electric bills charge for energy, so this calculator converts watts and hours into kilowatt-hours.

Appliance energy breakdown

Power multiplied by time and converted to kWh.

MeasureEstimate
Daily kWh2.4 kWh
Monthly kWh72 kWh
Daily cost$0.43
Monthly cost$12.96

Formula

Appliance wattage formula

kWh = watts x quantity x hours / 1000; cost = kWh x electricity rate

Actual use can be lower than nameplate wattage when appliances cycle on and off.

How to use

Steps

  1. Enter the wattage listed on the appliance label or product manual.
  2. Enter quantity if you run more than one of the same device.
  3. Enter hours per day and days per month.
  4. Enter your electricity rate in cents per kWh.

Example

Sample calculation

Watts1,200
Use2 hours/day for 30 days
Energy72 kWh/month
At 18 cents/kWh$12.96/month

Calculator use

Best for

  • Quick appliance energy cost from watts, quantity and hours per day.
  • Quick everyday math with the result and formula in one place.
  • Shopping, date, time, unit, school, or household comparisons.
  • A fast check before moving the numbers into a spreadsheet.

Before relying on it

Check first

  • Entering watts, quantity and hours per day from different time periods or scenarios.
  • Mixing units, dates, or original values across the same calculation.
  • Rounding early and then using the rounded number in another step.
  • Copying a result without checking whether the inputs match the real-world question.

Details

What to know before using the result

These notes make the assumptions explicit, especially where the same search query can mean slightly different things.

WattsInstant power draw

Watts describe how much power the device uses while running at that setting.

Kilowatt-hoursPower over time

Electric bills use energy over time, so watts are multiplied by hours and divided by 1,000.

Cycling appliancesAverage draw may vary

Refrigerators, HVAC, dehumidifiers, chargers, and heaters may cycle or change power levels during use.

Source notes

References used for this calculator

U.S. Department of EnergyShows the appliance energy cost formula and notes that actual wattage can vary by product and usage.U.S. Energy Information AdministrationExplains watts, watthours, and kilowatt-hours with examples of power used over time.

Benchmarks

How to read the result

The calculator is a decision aid, not a fixed rule. Use the output to compare scenarios and document your assumptions.

Under 100WLow draw

Common for LED lights, chargers, fans, and efficient electronics.

500W - 1,500WHigh draw

Common for heaters, microwaves, hair dryers, kettles, and some kitchen appliances.

Runs dailyCost compounds

Even a modest wattage can matter if it runs for many hours every day.

Calculator accuracy

Methodology and assumptions

The formula, inputs, example, and limitations are shown so the result is checkable, not just a number in a box.

Formula

kWh = watts x quantity x hours / 1000; cost = kWh x electricity rate

Inputs used

Watts, Quantity, Hours per day, Days per month, Electricity rate

Limitations

Results are estimates for quick planning and should be checked before important financial, legal, tax, health, or business decisions.

Last reviewed

May 25, 2026

Cite this page

Toolkit Shelf. Appliance Wattage Calculator. Retrieved May 25, 2026, from https://toolkitshelf.com/tools/appliance-wattage-calculator

FAQ

Common questions

How do I convert watts to kWh?

Multiply watts by hours used, then divide by 1,000. For cost, multiply kWh by your electricity rate.

Where do I find appliance wattage?

Check the appliance label, manual, product page, or a plug-in energy meter. Some labels show amps and volts instead of watts.

Why is actual cost different?

Many devices cycle, change modes, or use less than rated wattage during normal operation. Utility rates and fees also vary.