About this converter
Energy is the capacity to do work, measured in joules (J) — the SI unit named after James Prescott Joule. In electrical engineering and utility billing, the kilowatt-hour (kWh) is the dominant practical unit: 1 kWh = 3,600,000 J exactly. The same quantity is expressed in BTU for HVAC loads, in calories for thermal and food energy, and in electronvolts (eV) for quantum-scale physics.
Electrical engineers, energy billing analysts, HVAC designers, and physicists all work with energy quantities in different units. This converter handles the full practical range from electronvolts (1.6 × 10⁻¹⁹ J) to megawatt-hours (3.6 × 10⁹ J), covering utility metering, battery sizing, heating load calculations, and particle physics in one tool.
How to Use This Converter
- Enter the energy value in the Value field.
- Select the source unit from the From dropdown.
- Select the target unit from the To dropdown.
- Read the converted result and the formula line.
- Use Swap to reverse the conversion direction.
Units Covered
| Unit | Symbol | Common Use |
|---|---|---|
| Joule | J | SI base unit; used in physics, mechanics, and as the bridge between energy scales. |
| Kilojoule | kJ | Food energy labels (1 food calorie = 4.184 kJ) and chemical thermodynamics. |
| Megajoule | MJ | Battery capacity specs and industrial energy accounting (1 kWh = 3.6 MJ). |
| Watt-hour | Wh | Small battery capacity — power banks and e-bike batteries are rated in Wh. |
| Kilowatt-hour | kWh | Electricity billing and household appliance energy consumption. |
| Megawatt-hour | MWh | Commercial and industrial electricity metering and power plant output. |
| British Thermal Unit | BTU | HVAC heating/cooling loads and US gas appliance ratings. |
| Calorie | cal | Chemistry lab measurements and historical thermal calculations. |
| Kilocalorie | kcal | Food nutrition labels — the "Calorie" on food packaging = 1 kcal = 4,186.8 J. |
| Electronvolt | eV | Semiconductor band gaps, photon energies, and particle physics calculations. |
Kilowatt-hours to Joules Conversion Table
| From | To |
|---|---|
| 0.001 kWh | 3,600 J |
| 0.01 kWh | 36,000 J |
| 0.1 kWh | 360,000 J |
| 0.5 kWh | 1,800,000 J |
| 1 kWh | 3,600,000 J |
| 2 kWh | 7,200,000 J |
| 5 kWh | 18,000,000 J |
| 10 kWh | 36,000,000 J |
| 50 kWh | 180,000,000 J |
| 100 kWh | 360,000,000 J |
How to Convert Kilowatt-hours to Joules
Kilowatt-hours to joules
For example, 1.5 kWh × 3,600,000 = 5,400,000 J — the energy stored in a typical 1.5 kWh laptop battery.
Joules to kilowatt-hours
For example, 7,200,000 J / 3,600,000 = 2 kWh — the charge added to an EV battery during a short top-up.
When You Need to Convert Energy
Electrical engineers and energy auditors convert between kWh and joules when comparing utility meter readings to simulation outputs. A residential meter reading of 350 kWh/month equals 1.26 × 10⁹ J. Battery storage systems are rated in kWh commercially but require joule-based inputs for power-flow simulations, making accurate conversion essential for grid-scale modeling.
HVAC designers work in BTU and kcal for heating and cooling loads, while energy simulation software accepts kWh or joules. A 24,000 BTU/h air conditioner running 8 hours delivers 192,000 BTU = 202.6 MJ = 56.3 kWh. Converting across BTU, kWh, and MJ is routine when matching equipment ratings to building energy models and utility billing data.
Physicists and semiconductor engineers use electronvolts for atomic-scale energy. Silicon has a 1.1 eV band gap = 1.76 × 10⁻¹⁹ J. LED photon energies (1.8–3.1 eV for visible light) must be converted to joules for optical power calculations. Bridging eV and macroscopic energy units is essential when moving between quantum device design and system-level power budgets.