Energy Converter
Convert kilowatt-hours, BTU, therms, joules, calories and food Calories, foot-pounds and electronvolts.
–
- Result
- Formula
- Reverse
- Exact?
In Every Unit
| Unit | Value |
|---|
Saved Conversions
Conversions you add are saved in this browser.
| Note | Conversion | Remove |
|---|
How to Convert Energy Units
All energy units reduce to joules. A watt-hour is one watt for one hour, or 3,600 J, and a kWh is 3.6 million J. The BTU used here is the International Table BTU, 1,055.056 J.
BTU = kWh × 3,412.14 kJ = kcal × 4.184 kWh = therms × 29.3001
Worked Example
Common Conversions
| From | Equals |
|---|---|
| 1 kWh | 3,412.142 BTU |
| 1 BTU | 0.0002930711 kWh |
| 1 kcal | 4.184 kJ |
| 1 kJ | 0.2390057 kcal |
| 1 thm | 29.30011 kWh |
| 1 J | 0.2390057 cal |
| 1 ft·lbf | 1.355818 J |
Unit Definitions
| Unit | Equals | Exact? |
|---|---|---|
| Joules (J) | 1 J | Exact |
| Kilojoules (kJ) | 1,000 J | Exact |
| Megajoules (MJ) | 1,000,000 J | Exact |
| Calories (small) (cal) | 4.184 J | Exact |
| Kilocalories (food Calories) (kcal) | 4,184 J | Exact |
| Watt-hours (Wh) | 3,600 J | Exact |
| Kilowatt-hours (kWh) | 3,600,000 J | Exact |
| BTU (IT) (BTU) | 1,055.055853 J | Exact |
| Thousand BTU (MBtu) | 1,055,055.852999999886 J | Exact |
| Therms (US) (thm) | 105,480,400 J | Exact |
| Foot-pounds (ft·lbf) | 1.355817948 J | Exact |
| Electronvolts (eV) | 1.602176634 × 10⁻¹⁹ J | Exact |
| Ergs (erg) | 1 × 10⁻⁷ J | Exact |
Factors follow NIST Special Publication 811, Appendix B. "Exact" means the unit is defined as that value; results are rounded only for display.
Tips
Food labels' "Calories" are kilocalories. The calorie here is the thermochemical calorie (4.184 J); the older International Table calorie is 4.1868 J, a 0.07% difference. The US therm is 100,000 BTU (EEC therm definition, 105.4804 MJ).