MJ to kWh Converter
1 kWh = 1,000 W × 3,600 s = 3,600,000 J = 3.6 MJ exactly. Therefore 1 MJ = 1 / 3.6 = 0.27778 kWh. The conversion is exact because every unit in the chain is defined by SI base...
Formula
Source: International System of Units (SI), NIST SP 811 | Last reviewed: June 27, 2026
Examples
1 MJ
= 0.2778 kWh
1 MJ = 0.2778 kWh
3.6 MJ
= 1 kWh
3.6 MJ = 1 kWh (the exact reference)
100 MJ
= 27.78 kWh
100 MJ = 27.8 kWh, typical daily household electricity
1000 MJ
= 277.78 kWh
1,000 MJ (1 GJ) = 277.8 kWh
3600 MJ
= 1000 kWh
3,600 MJ = 1,000 kWh (1 MWh)
Quick Reference Table
| MJ | kWh | Context |
|---|---|---|
| 1 | 0.278 | 1 MJ |
| 3.6 | 1 | Exactly 1 kWh |
| 10 | 2.78 | Small energy quantity |
| 36 | 10 | 1 L diesel chemical energy |
| 100 | 27.8 | Approximate daily household electricity |
| 1000 | 278 | 1 GJ (gigajoule) |
| 3600 | 1000 | 1 MWh |
| 36000 | 10000 | 10 MWh, medium commercial monthly |
Where is this used?
Therefore 1 MJ = 1 / 3.6 = 0.27778 kWh.
The conversion is exact because every unit in the chain is defined by SI base units: 1 W = 1 J/s, 1 h = 3,600 s, mega = 10⁶.
The MJ scale is particularly useful for fuel analysis: 1 liter of diesel contains approximately 36 MJ of chemical energy (lower heating value), which if converted to electricity at 100% efficiency would be 10 kWh.
At a practical diesel generator efficiency of 35%, 1 liter of diesel produces approximately 3.5 kWh of electricity, a number that's useful for remote power system sizing.
1 kg of natural gas (methane) contains about 50 MJ of energy (LHV), equivalent to 13.9 kWh, if burned in a combined-cycle power plant at 55% efficiency, this yields 7.6 kWh of electricity.
In European energy statistics and building energy performance, MJ and GJ (gigajoules) are commonly used alongside kWh: the EU Energy Performance of Buildings Directive (EPBD) reports primary energy consumption in kWh/m²·yr, but national implementations (e.g., the German Energieausweis, the French DPE, Diagnostic de Performance Énergétique) may use kWh, MJ, or both.
The conversion factor 3.6 is one of the most useful energy conversion numbers to memorize: 1 kWh = 3.6 MJ, and therefore 1 MJ = 1/3.6 kWh = 0.2778 kWh.
The GJ (1,000 MJ) is also common: 1 GJ = 277.8 kWh, and 1 MWh = 3.6 GJ.
At the utility scale: 1 GWh (1,000 MWh) = 3.6 TJ (terajoules), and 1 TWh = 3.6 PJ (petajoules), the annual electricity consumption of a medium-sized country (e.g., the Netherlands at about 120 TWh/yr) is about 432 PJ of electrical energy.
The MJ-to-kWh conversion is also essential in chemical engineering for converting reaction enthalpies (ΔH in kJ/mol or MJ/kmol) to electrical energy equivalents for electrochemical process design, a hydrogen electrolyzer that requires 50 kWh per kg of hydrogen (180 MJ/kg) and produces hydrogen with a lower heating value of 120 MJ/kg has a system efficiency of 120/180 = 66.7% (HHV basis).
The conversion between MJ and kWh is the only energy conversion that is exact (involving only definitional SI units), no messy experimental constants like the BTU.
Real-World Usage Scenarios
Solar PV system energy yield calculation
A 10 MW solar PV system in the Mojave Desert (annual solar irradiation of approximately 2,500 kWh/m²/yr, or 9.0 GJ/m²/yr) produces energy according to: E_annual = A × G × η_system × (1 - T_loss). For a 10 MW system (10,000 kW nameplate) with 70% capacity factor: 10,000 × 0.70 × 8,760 = 61,320 MWh/year = 220,752 GJ/year. The MJ-to-kWh conversion (÷ 3.6 or × 0.2778) is implicit at every step. The output is reported in kWh for grid sales (the utility pays in $/MWh or $/kWh) and in MJ/GJ for engineering documentation and energy audits (more common in European or international contexts). The kWh is the unit of grid delivery; the MJ is the unit of thermodynamic energy. Both are needed for complete project documentation.
Industry Standards Referenced
Frequently Asked Questions
Why is the MJ-to-kWh conversion exact?
Because every unit in the chain is defined by SI base units: 1 J = 1 kg·m²/s², 1 W = 1 J/s, 1 h = 3,600 s, mega = 10⁶. Therefore 1 kWh = 1,000 × 3,600 = 3,600,000 J = 3.6 MJ. No measurement uncertainty, no experimental constant. This is one of the rare perfectly exact conversions in engineering.
How does the MJ compare to the BTU?
1 MJ = 947.8 BTU. 1 BTU = 1.055 kJ = 0.001055 MJ. A typical US home's annual natural gas consumption of 50 million BTU = 52,750 MJ = 52.75 GJ. The GJ (gigajoule, 1,000 MJ) is the SI equivalent of the MMBTU (1 MMBTU = 1.055 GJ). European natural gas billing is increasingly in kWh (converted from MJ), while the US uses therms or CCF. A European gas bill showing 15,000 kWh of gas consumption is equivalent to 15,000 × 3.6 = 54,000 MJ = 54 GJ. In a global engineering context, MJ and GJ are the preferred bridge units between US (BTU/MMBTU) and European (kWh) data.
What does this converter do?
This converter performs the unit conversion at standard conditions using the exact conversion factor. The result is displayed with appropriate precision for engineering use.
Reviewed for accuracy
Verified against SI definitions · Last reviewed: June 27, 2026
All calculations are for reference only. Always verify with manufacturer data and a qualified engineer for critical applications. Learn about our editorial process.