Kilowatt Hour (kWh) Calculator
Calculate energy consumption and electricity costs
Look for 'W' on your device label.
Average daily runtime.
Calculation period (30 for monthly).
Check your utility bill for the rate.
Total Energy (kWh)
0.00
Estimated Cost
$0.00
What is a Kilowatt-Hour (kWh)?
A kilowatt-hour (kWh) is a unit of measurement used by utility companies to quantify the amount of energy consumed over a specific period. It does not represent 1,000 watts per hour; rather, it represents the energy equivalent of burning 1,000 watts of power continuously for one full hour.
The kWh Calculation Formula
To calculate the kilowatt-hours of any electrical appliance, you can use the following standard physics formula:
kWh = (Watts × Hours per Day × Number of Days) ÷ 1,000
How to Calculate Energy Cost
Once you have the total kWh, finding the cost is straightforward. Multiply the energy consumption by your local utility rate (expressed in dollars or cents per kWh):
Cost = Total kWh × Utility Rate
Realistic Examples
| Appliance | Wattage | Daily Use | Monthly Cost ($0.14 rate) |
|---|---|---|---|
| LED Light Bulb | 10W | 6 Hours | $0.25 |
| Laptop Computer | 60W | 8 Hours | $2.02 |
| Space Heater | 1,500W | 4 Hours | $25.20 |
Tips for Reducing Your Electricity Bill
- Switch to LEDs: LED bulbs use up to 80% less energy than traditional incandescent bulbs.
- Unplug "Phantom" Loads: Many electronics draw power even when turned off. Use smart power strips to cut power completely.
- Optimizing Large Appliances: Run dishwashers and laundry machines only with full loads to maximize the energy-to-use ratio.
- Adjust Your Thermostat: Heating and cooling are usually the largest part of a home's kWh consumption. Even a 1-2 degree shift can save significantly.