kWh Calculator
Calculate kilowatt-hours (kWh) from watts and hours of use. Includes optional electricity cost estimation.
Energy Consumed— kWh
Estimated Cost—
How to Calculate kWh
kWh = (Watts × Hours) / 1000
Kilowatt-hours represent energy consumption over time. Multiply your device's wattage by the number of hours used, then divide by 1,000 to convert from watt-hours to kilowatt-hours.
Cost Calculation
Cost = kWh × Rate per kWh
To estimate the electricity cost, multiply the energy consumed (kWh) by your electricity rate. The average US rate is approximately $0.12–$0.16 per kWh.
Example:
A 1,500W space heater running for 8 hours:
kWh = (1500 × 8) / 1000 = 12 kWh
Cost at $0.12/kWh = 12 × 0.12 = $1.44
A 1,500W space heater running for 8 hours:
kWh = (1500 × 8) / 1000 = 12 kWh
Cost at $0.12/kWh = 12 × 0.12 = $1.44
FAQ
What is a kWh?
A kilowatt-hour (kWh) is a unit of energy equal to using 1,000 watts for one hour. It's the standard billing unit for electricity.
How do I find my electricity rate?
Check your electricity bill — the rate per kWh is usually listed. In the US, it typically ranges from $0.10 to $0.30 depending on your state and provider.
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Last updated: 2026-08-08