How do I convert calories to kilojoules?

To convert calories to kilojoules, enter your value in the converter above. We support joules, calories, kilowatt-hours, BTUs, and more.

How accurate are these energy conversions?

Our conversions use precise scientific conversion factors accurate to multiple decimal places. This is important for scientific calculations, engineering, and nutrition analysis.

Calorie to Kilojoule Converter

Convert Calories to Kilojoules instantly

From

cal

Result

0kJ

Kilojoule

Conversion Formula

Kilojoule = Calorie × 0.004184

Where:

cal = Calorie
kJ = Kilojoule

What is a Calorie?

The calorie (cal) is a unit of energy in the metric system of measurement.

What is a Kilojoule?

The kilojoule (kJ) is a unit of energy in the metric system of measurement.

How to Convert Calorie to Kilojoule

Convert calories to kilojoules instantly

Quick Reference:

1 cal = 0.004184 kJ
1 kJ = 239.005736 cal

Common Calorie to Kilojoule Conversions

1 cal
= 0.00 kJ

5 cal
= 0.02 kJ

10 cal
= 0.04 kJ

25 cal
= 0.10 kJ

50 cal
= 0.21 kJ

100 cal
= 0.42 kJ

Conversion Reference Table

Calorie (cal)	Kilojoule (kJ)
1	0.0042
2	0.0084
3	0.0126
4	0.0167
5	0.0209
10	0.0418
15	0.0628
20	0.0837
25	0.1046
50	0.2092
75	0.3138
100	0.4184
250	1.046
500	2.092
1,000	4.184

Quick reference table showing common calories to kilojoules conversions.

Real-World Energy Conversions

⚡

Electricity Bills

Understanding your power consumption in kilowatt-hours (kWh). A 100W bulb running for 10 hours uses 1 kWh. Convert kWh to joules or BTU for energy calculations.

🍎

Food and Nutrition

Converting between Calories (kcal) and joules for nutritional information. Food energy content is measured in Calories, with 1 Calorie equaling approximately 4.2 kilojoules.

🔥

Heating and Cooling

HVAC systems use BTU (British Thermal Units) to measure heating/cooling capacity. Converting BTU to watts or joules helps compare different systems.

🔬

Physics and Science

Scientific calculations use joules as the SI unit of energy. Converting between joules, kilojoules, and megajoules for physics problems and research.

🔋

Battery Capacity

Batteries are rated in watt-hours (Wh) or milliamp-hours (mAh). Converting between units helps compare battery performance and runtime.

⛽

Fuel Energy Content

Fuels are compared using energy content per unit mass or volume. Converting between joules per gram, BTU per pound, or kWh per liter.

Energy Conversion FAQs

Common Conversion Mistakes

⚠Confusing the direction of conversion — always check whether you are converting from Calorie to Kilojoule or vice versa.
⚠Rounding too early in multi-step calculations. Keep full precision until the final result.
⚠Using outdated or approximate conversion factors. Our converter uses values traceable to international measurement standards.

Sources & Standards

Conversion factors on this page are based on definitions from the International Bureau of Weights and Measures (BIPM) and the National Institute of Standards and Technology (NIST). All factors are accurate to at least 6 decimal places.

Last updated: November 27, 2025