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What is a kilowatt-hour?

The standard electricity-bill unit — 1 kW × 1 hour

Definition

The kilowatt-hour equals 3.6 megajoules — energy delivered by 1 kW for 1 hour. It is the standard unit on electricity bills worldwide. A UK home uses about 2900 kWh/year; an EV charge adds 10–80 kWh depending on battery.

Common uses

  • Electricity billing globally
  • EV battery capacity specifications
  • Home solar and battery storage

🌍 Real-world scale

UK home: ~2900 kWh/year. Tesla Model 3 battery: 60–80 kWh. Typical EV efficiency: 15–20 kWh/100 km.

Convert from kilowatt-hours

9 conversions
Kilowatt-Hour to Joule1 kWh = 3,600,000 JKilowatt-Hour to Kilojoule1 kWh = 3,600 kJKilowatt-Hour to Megajoule1 kWh = 3.6 MJKilowatt-Hour to Watt-Hour1 kWh = 1,000 WhKilowatt-Hour to Calorie1 kWh = 860,420.65 calKilowatt-Hour to Kilocalorie1 kWh = 860.421 kcalKilowatt-Hour to British Thermal Unit1 kWh = 3,412.14 BTUKilowatt-Hour to Electronvolt1 kWh = 2.2469e25 eVKilowatt-Hour to Therm1 kWh = 0.03412 thm

Convert to kilowatt-hours

9 conversions
Joule to Kilowatt-Hour1 J = 2.7778e-7 kWhKilojoule to Kilowatt-Hour1 kJ = 0.0002778 kWhMegajoule to Kilowatt-Hour1 MJ = 0.2778 kWhWatt-Hour to Kilowatt-Hour1 Wh = 0.001 kWhCalorie to Kilowatt-Hour1 cal = 1.1622e-6 kWhKilocalorie to Kilowatt-Hour1 kcal = 0.001162 kWhBritish Thermal Unit to Kilowatt-Hour1 BTU = 0.0002931 kWhElectronvolt to Kilowatt-Hour1 eV = 4.4505e-26 kWhTherm to Kilowatt-Hour1 thm = 29.3071 kWh

Tips

  • 1 kWh = 3.6 MJ = 3,600,000 J.
  • Multiply device power (kW) × time (h) = energy (kWh).
  • EV "range anxiety" translates to knowing kWh available.

Common mistakes

  • Confusing kWh (energy) with kW (power).
  • Calculating electric costs by power ignoring duration.
  • Using "kWh/h" — redundant; it's just kW.

FAQ about the kilowatt-hour

What is a kilowatt-hour?
The kilowatt-hour equals 3.6 megajoules — energy delivered by 1 kW for 1 hour. It is the standard unit on electricity bills worldwide. A UK home uses about 2900 kWh/year; an EV charge adds 10–80 kWh depending on battery.
Where is the kilowatt-hour used?
The kilowatt-hour is commonly used for: Electricity billing globally; EV battery capacity specifications; Home solar and battery storage.
What is an example of a kilowatt-hour in real life?
UK home: ~2900 kWh/year. Tesla Model 3 battery: 60–80 kWh. Typical EV efficiency: 15–20 kWh/100 km.
What category does the kilowatt-hour belong to?
The kilowatt-hour is a unit of energy, part of the 10-unit energy category on UnitConv.
How accurate are kilowatt-hour conversions?
All conversion factors follow NIST and BIPM international standards to 8 significant figures — the highest practical accuracy.
Explore all 10 energy units and their conversions.⚡ Energy hub →