How do I convert kJ to kcal?

Divide the kJ value by 4.184. For example, 418.4 kJ is 100 kcal. Converting back, 200 kcal multiplied by 4.184 gives 836.8 kJ.

Is a food Calorie the same as a calorie?

A food Calorie (Cal) is a kilocalorie (kcal). One kcal is 1,000 cal. Using the thermochemical definition, 1 kcal is 4.184 kJ.

Why do calorie conversion tables sometimes disagree?

Check the definition and rounding. A thermochemical kilocalorie is 4.184 kJ, while an International Table kilocalorie is 4.1868 kJ.

How many kcal are in 1 kWh?

About 860.42 thermochemical kcal. One kWh is 3,600 kJ, so divide 3,600 by 4.184.

How do I convert joules to kWh?

Divide joules by 3,600,000. A kilowatt is 1,000 watts and an hour is 3,600 seconds, so 1 kWh equals 3,600,000 joules.

When should I use eV instead of joules?

Electronvolts are convenient for atomic and particle energies. For example, 1 eV is exactly 1.602176634 × 10⁻¹⁹ J.

Lifestyle Tools

Energy Converter — kJ to kcal, kcal to kJ and J to kWh

Convert food energy between kilojoules and kilocalories, or electricity between joules and kilowatt-hours. Compare 13 units, check the formula and copy your result.

About Energy Converter — kJ to kcal, kcal to kJ and J to kWh

Kilojoules to kilocalories: quick reference

With the thermochemical definition, 1 kcal = 4.184 kJ. Divide kilojoules by 4.184 to get kilocalories. Multiply kilocalories by 4.184 to go the other way.

Common food energy values (kcal rounded to two decimal places where needed)
Kilojoules	Kilocalories
1 kJ	≈ 0.24 kcal
100 kJ	≈ 23.90 kcal
418.4 kJ	100 kcal
836.8 kJ	200 kcal
1,000 kJ	≈ 239.01 kcal

A food Calorie (capital C) means one kilocalorie, or 1,000 small calories. Printed kJ and kcal values can differ slightly from a direct conversion because of nutrient-specific energy factors and label rounding.

Energy units you can compare

Choose from 13 units: J, kJ, MJ, Wh, kWh, MWh, cal, kcal, eV, International Table BTU, US therms, ergs and foot-pounds force. Use the shortcuts for food labels and electricity, or select any two units to see the result and formula.

For a specification that uses International Table calories, compare calorie conventions in the heat converter (Japanese).

Joules and kilowatt-hours

One watt is one joule per second. Running at 1,000 W for 3,600 seconds uses 3,600,000 J = 3.6 MJ = 1 kWh. For example, 900,000 J equals 0.25 kWh. To find an energy from a power rating in kW, you also need the duration.

Which calorie or BTU does my source use?

This calculator uses 4.184 J per thermochemical calorie. An International Table calorie is 4.1868 J, and a mean calorie is 4.19002 J. Check the convention before comparing technical reference tables.

One International Table BTU is 1,055.05585262 J. The US therm used here is 105.4804 MJ. One electronvolt is exactly 1.602176634 × 10⁻¹⁹ J.

Using the calculator

Enter a signed number, decimal or scientific notation such as 1e3. Select a preset or swap units to keep the input number and recalculate it in the new direction. Copy the formula and result together, or open the manual copy field.

The output shows up to 12 significant digits. Precision decreases near the smallest representable numbers. If a conversion overflows or a nonzero result rounds to zero, that result is marked out of range. Other representable results remain available in the list.

Frequently asked questions

Q. How do I convert kJ to kcal?: Divide the kJ value by 4.184. For example, 418.4 kJ is 100 kcal. Converting back, 200 kcal multiplied by 4.184 gives 836.8 kJ.
Q. Is a food Calorie the same as a calorie?: A food Calorie (Cal) is a kilocalorie (kcal). One kcal is 1,000 cal. Using the thermochemical definition, 1 kcal is 4.184 kJ.
Q. Why do calorie conversion tables sometimes disagree?: Check the definition and rounding. A thermochemical kilocalorie is 4.184 kJ, while an International Table kilocalorie is 4.1868 kJ.
Q. How many kcal are in 1 kWh?: About 860.42 thermochemical kcal. One kWh is 3,600 kJ, so divide 3,600 by 4.184.
Q. How do I convert joules to kWh?: Divide joules by 3,600,000. A kilowatt is 1,000 watts and an hour is 3,600 seconds, so 1 kWh equals 3,600,000 joules.
Q. When should I use eV instead of joules?: Electronvolts are convenient for atomic and particle energies. For example, 1 eV is exactly 1.602176634 × 10⁻¹⁹ J.

Sources and specifications

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