Energy Converter
Convert energy units used for food labels, electricity bills, heating and physics — including kcal to kJ and kWh to BTU.
Result
Enter a value to convert.
How to use this calculator
- Enter an amount of energy and pick the units.
- Food labels use kilocalories (shown as “Calories” or “kcal”) and kilojoules.
- Every unit is listed below the main result.
Formula
Every unit is converted through joules:
- 1 kcal (food Calorie) = 4,184 J = 4.184 kJ
- 1 Wh = 3,600 J and 1 kWh = 3.6 MJ
- 1 BTU (International Table) ≈ 1,055.056 J
Worked example
A food label
250 kcal × 4.184 = 1,046 kJ.
Electricity to heat
1 kWh = 3.6 MJ ≈ 3,412 BTU.
Assumptions and limitations
- Uses the thermochemical calorie (4.184 J), the standard for nutrition. Other calorie definitions differ by less than 0.1%.
- The BTU uses the International Table definition.
Frequently asked questions
Is a food Calorie the same as a calorie?
No. A food Calorie (capital C) is a kilocalorie — 1,000 small calories.
What is the difference between kW and kWh?
kW is power (a rate). kWh is energy: running 1 kW for one hour uses 1 kWh.