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Quick Reference: Common Energy Conversions
- 1 kcal = 4.184 kJ = 1.163 Wh = 3.968 BTU
- 1 kWh = 3,600 kJ = 860 kcal = 3,412 BTU
- 1 BTU = 1,055 J = 0.252 kcal = 0.000293 kWh
- 1 eV = 1.602 × 10⁻¹⁹ J
- 1 MJ = 277.8 Wh = 238.8 kcal = 947.8 BTU
The Energy Converter on TechConverter.me handles all of these conversions instantly, displaying all equivalent values simultaneously so you can work across different unit systems without manual calculation.
Examples
Example 1: Nutrition — Food Calories to Joules
A nutritionist needs to convert food energy values between kilocalories (as shown on food labels) and kilojoules (used in scientific literature):
Input: 250 kcal (food calories)
Output:
1,046.7 kJ (kilojoules)
1,046,700 J (joules)
250,000 cal (small calories)
0.291 Wh (watt-hours)
Note: Food labels use "Calories" (capital C) to mean kilocalories. One food Calorie = 1,000 small calories = 4,184 joules. The converter clearly distinguishes between cal (small calorie) and kcal (kilocalorie/food Calorie) to avoid this common source of confusion.
Example 2: Electrical Energy — Kilowatt-Hours
An energy manager calculates the energy consumption of a data center server running at 500W for 24 hours:
Input: 12 kWh (500W × 24h)
Output:
43,200,000 J (43.2 MJ)
43,200 kJ
12,000 Wh
41,000 BTU
10,320 kcal
2.69 × 10^26 eV (electron volts)
This helps compare the energy cost of the server against other energy sources — for example, 12 kWh is equivalent to burning approximately 1.3 liters of gasoline (which contains about 9.5 kWh/liter of energy).
Example 3: HVAC Engineering — BTU Conversions
An HVAC engineer is sizing an air conditioning unit. The room requires 18,000 BTU/hour of cooling capacity:
Input: 18,000 BTU
Output:
19,000,000 J (19 MJ)
5,275 Wh
5.275 kWh
4,536 kcal
18,000 BTU
Cooling capacity: 18,000 BTU/hr = 1.5 tons of refrigeration = 5.275 kW
The converter helps the engineer compare the BTU rating with the kW rating used in European equipment specifications.