This online calculator converts energy between joules (J) and kilowatt-hours (kWh) using the exact SI relationships. It is intended for quick checks, billing comparisons, and engineering homework where precise unit handling matters. Abbreviations used: J (joule), kWh (kilowatt-hour), MJ (megajoule).
Kilowatt-hours (kWh) to Joules (J) Converter
Enter a value in kilowatt-hours and press the button to convert it to joules
Kilowatt-hours (kWh)
Result in Joules (J)
How to Use
- Enter a number in the input field. Choose joules or kilowatt-hours depending on the direction of conversion in your widget.
- Click “Convert” to compute the result instantly.
- Adjust “Decimal Places” to control rounding from 0 to 10 places (engineering-friendly).
- Use “Copy Result” to place the value on your clipboard.
- Click “Clear All” to reset inputs, result, and the shown calculation process.
- Use the “Swap” button (if enabled in your UI) to switch between J → kWh and kWh → J modes.
Definitions and Unit Details
Joule (J) — the SI unit of energy; 1 J = 1 kg·m²/s². System: SI (derived). In this calculator, 1 J equals 0.000000277777… kWh (exactly 1/3,600,000 kWh). Common cross-reference: 1 J = 0.001 kJ; 1 MJ = 1,000,000 J. In some mechanical contexts, energy is also expressed in foot-pound force (ft·lbf); by definition 1 ft·lbf = 1.355818 J, so 1 J ≈ 0.737562 ft·lbf.
Kilowatt-hour (kWh) — a non-SI energy unit widely used for electricity billing and appliances. It is exactly the energy of 1 kW sustained for 1 hour. System: non-SI (accepted for use with SI in practice). Relationship: 1 kWh = 3,600,000 J = 3.6 MJ (exact). This calculator uses that identity to convert between the two.
Conversion Formula
From joules to kilowatt-hours: EkWh = EJ ÷ 3,600,000.
From kilowatt-hours to joules: EJ = EkWh × 3,600,000.
Source: exact factors listed under “Energy” in the NIST Guide to the SI, Appendix B.9 (Conversion Factors).
Conversion Table (J → kWh)
| Joules (J) | Kilowatt-hours (kWh) |
|---|---|
| 1 | 0.000000277778 |
| 10 | 0.000002777778 |
| 50 | 0.000013888889 |
| 100 | 0.000027777778 |
| 500 | 0.000138888889 |
| 1,000 | 0.000277777778 |
| 5,000 | 0.001388888889 |
| 10,000 | 0.002777777778 |
| 50,000 | 0.013888888889 |
| 100,000 | 0.027777777778 |
| 500,000 | 0.138888888889 |
| 1,000,000 | 0.277777777778 |
| 5,000,000 | 1.388888888889 |
| 10,000,000 | 2.777777777778 |
| 50,000,000 | 13.888888888889 |
| 100,000,000 | 27.777777777778 |
| 500,000,000 | 138.888888888889 |
| 1,000,000,000 | 277.777777777778 |
| 5,000,000,000 | 1388.888888888889 |
| 10,000,000,000 | 2777.777777777778 |
Real-World Examples (Exact by Power × Time)
- 60 W incandescent lamp for 1 hour = 0.06 kWh = 216,000 J
- Electric kettle 1000 W for 3 minutes = 0.05 kWh = 180,000 J
- Smartphone charger 10 W for 2 hours = 0.02 kWh = 72,000 J
- Laptop power adapter 65 W for 1.5 hours = 0.0975 kWh = 351,000 J
- Microwave oven 1200 W for 5 minutes = 0.1 kWh = 360,000 J
- Dehumidifier 200 W for 24 hours = 4.8 kWh = 17,280,000 J
- EV Level-2 charger 7 kW for 30 minutes = 3.5 kWh = 12,600,000 J
- Hair dryer 1600 W for 10 minutes = 0.2666667 kWh ≈ 960,000 J
- Space heater 1500 W for 2 hours = 3.0 kWh = 10,800,000 J
- LED light strip 10 W for 24 hours = 0.24 kWh = 864,000 J
If you need any other online tools, tell us in the comments which ones would help you, and we will consider building them.
CalcuLife.com
Leave A Comment