kW and kWh: What is the Difference?

Reading time: ~5 minutes

Kilowatt (kW) and kilowatt-hour (kWh) are often confused, but they measure completely different things. This guide explains both clearly with practical examples.

What is a Watt (W) and Kilowatt (kW)?

Watt (W) is the unit of power — how fast energy is consumed or produced at any given moment. 1 kilowatt (kW) = 1000 watts.

Think of car speed: if a car is travelling at 100 km/h, that is its current speed. If a device draws 1000 W, that is its current power consumption.

• LED bulb: ~10 W
• 55" TV: ~100 W
• Washing machine (during wash): ~2000 W = 2 kW
• Electric heater (radiator): ~1500 W = 1.5 kW
• Solar array (4 kWp): up to 4000 W = 4 kW in full sun

What is a Kilowatt-hour (kWh)?

Kilowatt-hour (kWh) is the unit of energy — how much energy has been consumed or produced over a period of time.

Back to the car analogy: kWh is the distance travelled (km). Speed (kW) × time (hours) = distance (kWh).

kWh = kW × hours

• 2 kW washing machine running 1.5 h → 2 × 1.5 = 3 kWh
• 0.1 kW (100 W) TV running 4 h → 0.1 × 4 = 0.4 kWh
• 1.5 kW heater running 8 h → 1.5 × 8 = 12 kWh

What does your electricity bill measure?

Your electricity bill is denominated in kilowatt-hours (kWh). Your meter counts how many kWh you consume, and you are charged at a rate per kWh.

Example: if you consume 200 kWh per month at 0.18 €/kWh (example price), your monthly bill is 200 × 0.18 = €36 (at that example price).

Summary: kW vs kWh