Total kWh
0
Equivalent energy value
Accurate energy conversion between joules and kilowatt-hours — SI energy units made simple
Convert joules to kilowatt-hours (kWh) instantly with precise calculations. Includes bidirectional conversion and detailed breakdowns for electricity, physics, and engineering in 2026.
Professional energy conversion for electricity, physics, and engineering calculations
Convert joules to kilowatt-hours using the exact scientific relationship: 1 kilowatt-hour equals exactly 3,600,000 joules (3.6 × 10⁶ J). Our tool uses this internationally recognised standard to deliver accurate results for any energy value — from small electrical appliances to large industrial power consumption.
Switch seamlessly between joules to kilowatt-hours and kilowatt-hours to joules conversion modes. Get instant results with additional breakdowns in kilojoules, calories, BTU, and watt-hours — all from a single input value.
Essential for electricity billing calculations, home appliance energy audits, solar panel output assessments, battery capacity planning, and physics coursework. Joules to kWh conversion is one of the most commonly needed energy conversions in both everyday life and professional engineering.
Select conversion direction and enter your energy value below
The joule (J) is the SI unit of energy — the fundamental scientific measure used in physics, chemistry, and engineering. The kilowatt-hour (kWh) is a practical unit of energy used predominantly in electricity measurement, billing, and power systems. Both measure the same physical quantity, but at very different scales suited to different applications.
The relationship between them is exact: 1 kilowatt-hour = 3,600,000 joules (3.6 × 10⁶ J). This comes directly from the definition of a watt as one joule per second — a kilowatt is 1,000 watts, and one hour is 3,600 seconds, so 1 kWh = 1,000 × 3,600 = 3,600,000 joules. This conversion is critical for understanding electricity consumption and energy costs in real-world applications.
1 kWh = 3.6 × 10⁶ J | 1 J = 2.7778 × 10⁻⁷ kWh | 1 kWh = 1,000 Wh
Use this reference table to quickly look up common joule-to-kWh conversions. All values are calculated using the exact factor of 1 kWh = 3,600,000 J.
| Joules (J) | Kilowatt-Hours (kWh) | Watt-Hours (Wh) | Kilojoules (kJ) |
|---|---|---|---|
| 1 J | 0.000000278 kWh | 0.000278 Wh | 0.001 kJ |
| 100 J | 0.0000278 kWh | 0.0278 Wh | 0.1 kJ |
| 1,000 J | 0.000278 kWh | 0.278 Wh | 1 kJ |
| 10,000 J | 0.00278 kWh | 2.778 Wh | 10 kJ |
| 100,000 J | 0.0278 kWh | 27.78 Wh | 100 kJ |
| 360,000 J | 0.1 kWh | 100 Wh | 360 kJ |
| 1,000,000 J | 0.2778 kWh | 277.8 Wh | 1,000 kJ |
| 3,600,000 J | 1 kWh | 1,000 Wh | 3,600 kJ |
| 7,200,000 J | 2 kWh | 2,000 Wh | 7,200 kJ |
| 18,000,000 J | 5 kWh | 5,000 Wh | 18,000 kJ |
| 36,000,000 J | 10 kWh | 10,000 Wh | 36,000 kJ |
| 360,000,000 J | 100 kWh | 100,000 Wh | 360,000 kJ |
Use this reverse reference table for quick kWh-to-joule lookups. All values use the exact factor of 1 kWh = 3,600,000 J.
| Kilowatt-Hours (kWh) | Joules (J) | Kilojoules (kJ) | Megajoules (MJ) |
|---|---|---|---|
| 0.001 kWh | 3,600 J | 3.6 kJ | 0.0036 MJ |
| 0.01 kWh | 36,000 J | 36 kJ | 0.036 MJ |
| 0.1 kWh | 360,000 J | 360 kJ | 0.36 MJ |
| 0.5 kWh | 1,800,000 J | 1,800 kJ | 1.8 MJ |
| 1 kWh | 3,600,000 J | 3,600 kJ | 3.6 MJ |
| 2 kWh | 7,200,000 J | 7,200 kJ | 7.2 MJ |
| 5 kWh | 18,000,000 J | 18,000 kJ | 18 MJ |
| 10 kWh | 36,000,000 J | 36,000 kJ | 36 MJ |
| 50 kWh | 180,000,000 J | 180,000 kJ | 180 MJ |
| 100 kWh | 360,000,000 J | 360,000 kJ | 360 MJ |
The joule (J) is the derived SI unit of energy, work, and heat, named after English physicist James Prescott Joule (1818–1889). One joule is the energy transferred when a force of one newton moves an object one metre, or equivalently, the energy dissipated by one watt of power in one second (1 J = 1 W·s). It is the standard unit of energy across all scientific disciplines globally.
A kilowatt-hour (kWh) is a unit of energy equivalent to one kilowatt (1,000 watts) of power sustained for one hour. It is the standard unit used by electricity suppliers worldwide to measure and bill for energy consumption. On your electricity bill, every unit refers to one kWh of energy used. Despite not being an SI unit, the kWh is accepted for use alongside SI units because of its practical importance in energy metering.
1 kilowatt-hour = exactly 3,600,000 joules (3.6 MJ). This is not an approximation — it is a mathematically exact value derived from the definitions of the watt, the hour, and the joule. No rounding is needed when using the full factor.
Every unit of electricity on your bill is 1 kWh = 3,600,000 joules. If a device uses 1,800 watts (1.8 kW) for 2 hours, it consumes 3.6 kWh = 12,960,000 joules. Understanding this link between joules and kWh helps calculate real energy costs accurately.
The joule is too small a unit for practical electricity measurement. A typical UK household uses around 10 kWh per day — equivalent to 36,000,000 joules. Expressing this as 36 million joules on a utility bill would be impractical, which is why kWh remains the standard for energy billing.
Battery capacity is often listed in kWh for electric vehicles and home storage systems. A 60 kWh EV battery stores 216,000,000 joules (216 MJ) of energy. Converting kWh to joules is useful in physics and engineering when calculating discharge rates and power outputs.
A 5 kW solar panel system generating 20 kWh on a sunny day produces 72,000,000 joules of electrical energy. Engineers often work in joules and watts when sizing inverters and battery systems, then report final output in kWh for consumer clarity and billing purposes.
1 kWh = 1 kilowatt × 1 hour = 1,000 W × 3,600 s = 3,600,000 W·s = 3,600,000 J. Since 1 watt = 1 joule/second, 1 W·s = 1 J exactly. This dimensional chain confirms the conversion factor of 3,600,000 with full mathematical rigour.
Do not confuse kilowatt-hours (kWh) with kilowatts (kW). A kilowatt is a unit of power (rate of energy use), while a kilowatt-hour is a unit of energy (total energy consumed). A 3 kW appliance running for 2 hours uses 6 kWh of energy = 21,600,000 joules. Always multiply power (kW) by time (hours) before converting to joules.
Follow these simple steps to convert any joule value to kilowatt-hours accurately:
Ofgem regulates the UK electricity and gas markets. Their guides explain how kWh is used in energy billing, price caps, and consumption reporting for 2026.
Visit Ofgem →The National Institute of Standards and Technology provides the official guide on SI units including the joule, watt, and accepted non-SI units like the kilowatt-hour.
NIST Guide →The International Energy Agency publishes global energy consumption data in kWh and joules. Essential for understanding energy use at national and international scale.
IEA Data →