Kilowatt-Hour (kWh) Cost Calculator
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Kilowatt-Hour (kWh) Cost Calculator
Estimated Monthly Cost
—
USD
— kWh used per month
Understanding Your Electricity Costs
Electricity bills can sometimes be complex, but understanding how your appliances contribute to the total cost is key to managing your energy consumption and expenses. The Kilowatt-Hour (kWh) is the standard unit for measuring electricity usage. One kilowatt-hour represents the energy consumed by using one kilowatt (1000 watts) of power for one hour.
This calculator helps you estimate the monthly cost of running a specific appliance based on its power consumption (in watts), how many hours it's used per day, how many days it's used per month, and your electricity provider's rate per kWh.
How the Calculation Works:
The calculation involves a few straightforward steps:
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1. Convert Watts to Kilowatts: Since electricity is measured in kilowatt-hours, we first convert the appliance's wattage into kilowatts (kW) by dividing by 1000.
Formula: Kilowatts (kW) = Appliance Wattage (W) / 1000
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2. Calculate Daily Energy Consumption (kWh): We then determine the total energy consumed by the appliance each day.
Formula: Daily kWh = Kilowatts (kW) * Hours Used Per Day
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3. Calculate Monthly Energy Consumption (kWh): To find the total monthly usage, we multiply the daily consumption by the number of days the appliance is used in a month.
Formula: Monthly kWh = Daily kWh * Days Used Per Month
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4. Calculate Monthly Cost: Finally, we multiply the total monthly kWh consumption by the cost per kWh charged by your utility provider.
Formula: Monthly Cost = Monthly kWh * Cost Per kWh ($)
Example:
Let's say you have a laptop that consumes 75 watts and you use it for 5 hours per day, for 25 days in a month. Your electricity provider charges $0.12 per kWh.
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Kilowatts: 75 W / 1000 = 0.075 kW
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Daily kWh: 0.075 kW * 5 hours = 0.375 kWh
-
Monthly kWh: 0.375 kWh * 25 days = 9.375 kWh
-
Monthly Cost: 9.375 kWh * $0.12/kWh = $1.13 (rounded)
This means your laptop would cost approximately $1.13 per month to run under these conditions.
Use this calculator to understand the financial impact of your various appliances and identify opportunities to save energy and money by optimizing usage or considering more energy-efficient alternatives.
function calculateKwhCost() {
var wattage = parseFloat(document.getElementById("deviceWattage").value);
var hoursPerDay = parseFloat(document.getElementById("hoursPerDay").value);
var daysPerMonth = parseFloat(document.getElementById("daysPerMonth").value);
var costPerKwh = parseFloat(document.getElementById("costPerKwh").value);
var resultContainer = document.getElementById("resultContainer");
var monthlyCostElement = document.getElementById("monthlyCost");
var kwhUsedElement = document.getElementById("kwhUsed");
// Input validation
if (isNaN(wattage) || wattage <= 0 ||
isNaN(hoursPerDay) || hoursPerDay < 0 ||
isNaN(daysPerMonth) || daysPerMonth <= 0 ||
isNaN(costPerKwh) || costPerKwh < 0) {
alert("Please enter valid positive numbers for all fields.");
resultContainer.style.display = 'none';
return;
}
// Calculations
var kilowatts = wattage / 1000;
var dailyKwh = kilowatts * hoursPerDay;
var monthlyKwh = dailyKwh * daysPerMonth;
var monthlyCost = monthlyKwh * costPerKwh;
// Display results
monthlyCostElement.textContent = monthlyCost.toFixed(2);
kwhUsedElement.textContent = monthlyKwh.toFixed(2) + " kWh used per month";
resultContainer.style.display = 'block';
}