Energy Converter
Convert between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours and BTU.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
1 kJ ≈ 0.2390057361 kcal
About this calculator
Energy units are used differently by discipline: nutrition uses kilocalories, electricity uses kilowatt-hours and heating uses BTU. One kilocalorie equals 4,184 joules.
Worked example
calculated with the default values below
Value 1 · From Kilocalories (kcal; 1 kcal = 1,000 cal) · To Kilojoules (kJ) · Decimal places 4 Result 4.184 · Joules 4,184.00 J · Kilocalories 1.0000 kcal · Kilowatt-hours 0.001162 kWh
Method and assumptions
Formula basis and scope
Convert energy via joules; watt-hour = 3600 J.
Only the displayed unit definitions are converted; rounding and measurement uncertainty are separate.
Data sources
Disclaimer
These calculators give general conversion results. Rounding and the precision of the value you enter both affect the output, so treat displayed decimals as indicative rather than exact.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
E_out = E_in × f_in ÷ f_out
- E_in
- Input energy
- f_in
- Source factor in joules (J 1, cal 4.184, kcal 4184, Wh 3600, kWh 3.6×10⁶, BTU 1055.06)
- f_out
- Target factor
- E_out
- Converted energy
Also ft·lb 1.3558 and therm 1.055×10⁸; all factors are relative to the joule; pure unit conversion. `cal` means the thermochemical small calorie (4.184 J); 1 kcal = 1,000 cal. Food-label Calories are usually kilocalories.
Frequently asked questions
What is the difference between cal and kcal?
Here, cal means the thermochemical small calorie (4.184 J), while 1 kcal equals 1,000 cal (4,184 J). Food labels commonly use a capital-C Calorie to mean a kilocalorie. This converter uses the stated unit symbols and fixed conversion factors.