How do you calculate kilowatt-hours from watts and hours?

• A. kWh = Watts x Hours
• B. kWh = (Watts x Hours)/1000
• C. kWh = (Watts/1000) x Hours
• D. kWh = Watts x (Hours/1000)

Answer: (B)

Energy over time is found by multiplying power by how long it runs. Power in watts times time in hours gives energy in watt-hours. To express that energy in kilowatt-hours, you divide by 1000 because 1 kilowatt equals 1000 watts. So the clear way to write the conversion is kWh = (Watts × Hours) ÷ 1000. This shows exactly how to scale watt-hours into kilowatt-hours. For example, a 100 W device running for 2 hours uses 100 × 2 = 200 Wh, which is 0.2 kWh since 200 ÷ 1000 = 0.2.