Enter your device's Power (in your choice of Power Unit) and how long it runs (Time and Time Unit) to calculate its Energy Consumption in kWh — plus bonus outputs including Energy in Watt-hours, Daily Energy over 24 hours, and a full Monthly Energy estimate across 30 days.
Energy Consumption
--
Energy in Watt-hours
--
Daily Energy (24 hours)
--
Monthly Energy (30 days)
--
To convert watts to kWh, multiply the power in watts by the time in hours, then divide by 1,000. The formula is: Energy (kWh) = Power (W) × Time (hours) ÷ 1,000.
Watts (W) measure power - the rate of energy consumption at any moment. Kilowatt-hours (kWh) measure energy - the total amount of power used over time. Think of watts as speed and kWh as distance traveled.
A 1500W appliance running for 8 hours consumes 12 kWh (1500 × 8 ÷ 1000). At an average electricity rate of $0.12 per kWh, this would cost approximately $1.44.
Electric utility companies charge customers based on kilowatt-hours consumed, not watts. Your monthly bill shows total kWh usage multiplied by your rate per kWh, making this conversion essential for estimating costs.
Yes, you can convert kilowatts (kW) to kWh by multiplying by time in hours. For milliwatts, first convert to watts by dividing by 1,000, then use the standard formula.
Calculate daily kWh consumption first, then multiply by 365 days. For seasonal appliances, multiply daily usage by the number of days used per year instead of 365.