Kilowatt Calculator

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Kilowatt (kWh) Energy Consumption Calculator

Look for 'W' on your device label
Daily usage (0 – 24 hours)
National average is ~0.15

Calculation Results

Daily Consumption: 0 kWh

Monthly Consumption: 0 kWh

Annual Consumption: 0 kWh

Daily Cost: $0.00

Monthly Cost: $0.00

Annual Cost: $0.00

function calculateEnergyUsage() { var watts = parseFloat(document.getElementById('powerWatts').value); var hours = parseFloat(document.getElementById('hoursPerDay').value); var rate = parseFloat(document.getElementById('costPerKwh').value); if (isNaN(watts) || isNaN(hours) || watts <= 0 || hours 24) { alert("Hours per day cannot exceed 24."); return; } var dailyKwh = (watts * hours) / 1000; var monthlyKwh = dailyKwh * 30.44; // Average days in month var yearlyKwh = dailyKwh * 365; document.getElementById('dailyKwh').innerText = dailyKwh.toFixed(3); document.getElementById('monthlyKwh').innerText = monthlyKwh.toFixed(2); document.getElementById('yearlyKwh').innerText = yearlyKwh.toFixed(2); if (!isNaN(rate) && rate > 0) { document.getElementById('dailyCost').innerText = (dailyKwh * rate).toFixed(2); document.getElementById('monthlyCost').innerText = (monthlyKwh * rate).toFixed(2); document.getElementById('yearlyCost').innerText = (yearlyKwh * rate).toFixed(2); } else { document.getElementById('dailyCost').innerText = "0.00"; document.getElementById('monthlyCost').innerText = "0.00"; document.getElementById('yearlyCost').innerText = "0.00"; } document.getElementById('energyResults').style.display = 'block'; }

Understanding Kilowatt-Hours (kWh) and Energy Usage

A kilowatt-hour (kWh) is the standard unit used by electricity providers to measure the energy you consume over time. While "Watts" (W) represents the instantaneous power demand of an appliance, "kilowatt-hours" represents the total energy used during operation.

How the Calculation Works

Calculating your energy consumption is straightforward. The formula used by our calculator follows these steps:

  1. Convert Watts to Kilowatts: Divide the wattage of the device by 1,000 (since 1,000 Watts = 1 Kilowatt).
  2. Factor in Time: Multiply the Kilowatts by the number of hours the device is active.
  3. Calculate Cost: Multiply the resulting kWh by your local utility rate (expressed in dollars or cents per kWh).

Formula: (Watts × Hours) ÷ 1,000 = kWh

Example Energy Use Cases

To help you put these numbers into perspective, here are common household appliances and their typical consumption profiles:

  • Space Heater (1500W): Used for 4 hours a day = 6 kWh daily. At $0.15/kWh, this costs $0.90 per day.
  • LED Light Bulb (10W): Used for 10 hours a day = 0.1 kWh daily. This costs only $0.015 per day.
  • Central Air Conditioner (3500W): Used for 8 hours a day = 28 kWh daily. This costs $4.20 per day.
  • Laptop (60W): Used for 8 hours a day = 0.48 kWh daily. This costs roughly $0.07 per day.

Difference Between kW and kWh

It is a common misconception that kW and kWh are the same.

kW (Kilowatt) is a measure of power, indicating the capacity or demand. Think of it like the speed of a car (MPH). If a heater is rated at 2kW, that is how much power it draws the moment it is turned on.

kWh (Kilowatt-hour) is a measure of energy, indicating the volume or total work done. Think of it like the distance traveled (Miles). If you run that 2kW heater for 3 hours, you have consumed 6kWh of energy.

Tips to Lower Your Electricity Bill

By using this Kilowatt calculator, you can identify "energy vampires" in your home. To reduce costs, consider switching to LED lighting, using smart plugs to schedule appliance runtimes, and upgrading old appliances to ENERGY STAR® certified models which consume significantly fewer Watts for the same performance.

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