How do I calculate energy in kWh?

Energy (kWh) = Power (kW) × Time (hours). A 100W bulb running 10 hours = 0.1kW × 10h = 1 kWh.

What is the difference between kWh and Joules?

1 kWh = 3.6 million Joules = 3.6 MJ. kWh is used for billing; Joules for physics calculations.

1.5 kW × 8 hours = 12 kWh. At $0.12/kWh that costs $1.44.

Energy is power multiplied by time. E(kWh) = P(kW) × t(h) for practical billing, or E(J) = P(W) × t(s) for scientific use.

1 kWh = 3.6 MJ (million Joules). This is the unit your electricity bill uses.

kWh = kW × hours. A 100W bulb for 10 hours = 0.1 × 10 = 1 kWh.

1 kWh = 3.6 MJ. kWh for billing, Joules for physics.

1.5 kW × 8h = 12 kWh. At $0.12/kWh = $1.44/day.