How to use Energy Converter
- Enter the energy amount from your reading or calculation.
- Choose the source unit, checking whether calories mean cal or food kcal.
- Select the target unit and use the live answer. Swap reverses the calculation without retyping it.
A closer look
Energy units describe the same quantity in different contexts. A watt-hour is 3,600 joules and a kilowatt-hour is 3,600,000 joules. Calories here use the thermochemical definition: 1 cal = 4.184 J, so 1 kcal = 4,184 J. The BTU option uses the International Table definition of 1,055.05585262 J. Other historical calorie and BTU conventions are not interchangeable with these choices.
A practical example
One kilowatt-hour equals 3,600,000 joules. A kWh is energy; a kW is power, so the two labels cannot be substituted for one another.
A useful tip
A kilowatt measures power; a kilowatt-hour measures energy. To find energy from steady power, multiply kilowatts by hours before entering the number as kWh.
Good questions. Simple answers.
Which unit matches a food Calorie?
A food Calorie, often written with a capital C, means one kilocalorie. Choose kcal, not cal.
Can I convert a negative energy change?
Yes. Negative values can describe energy leaving a system. Unit conversion preserves the sign without interpreting the physical process.
Explore all converters for related tasks and category-specific guidance, or read how Toolzafi handles your data.