1 calorie converts to approximately 0.0042 kilojoules.
This is because 1 calorie, which measures energy, equals 4.184 joules, and since 1 kilojoule is 1000 joules, dividing 4.184 by 1000 give us about 0.0042 kj for 1 calorie.
Introduction
Converting 1 calorie to kilojoules involves understanding the relationship between these two units of energy. The calorie is a unit used mainly in food energy measurement, whereas kilojoules are part of the metric system, used worldwide for scientific measurements. The conversion is straightforward once you know the basic factor, which is 4.184 joules per calorie. When you convert, you simply multiply the number of calories by this factor and then divide by 1000 to get kilojoules.
Conversion Tool
Result in kj:
Conversion Formula
The conversion formula from calorie to kilojoule is: kj = calories * 4.184 / 1000. It works because 1 calorie equals 4.184 joules, and since 1 kilojoule is 1000 joules, dividing the joules by 1000 gives us the kilojoules. For example, converting 5 calories: 5 * 4.184 = 20.92 joules, then 20.92 / 1000 = 0.0209 kj.
Conversion Example
- Convert 2 calories:
- Multiply 2 by 4.184: 2 * 4.184 = 8.368 joules.
- Divide 8.368 by 1000: 8.368 / 1000 = 0.008368 kj.
- Convert 10 calories:
- 10 * 4.184 = 41.84 joules.
- 41.84 / 1000 = 0.04184 kj.
- Convert 0.5 calories:
- 0.5 * 4.184 = 2.092 joules.
- 2.092 / 1000 = 0.002092 kj.
- Convert 15 calories:
- 15 * 4.184 = 62.76 joules.
- 62.76 / 1000 = 0.06276 kj.
- Convert 20 calories:
- 20 * 4.184 = 83.68 joules.
- 83.68 / 1000 = 0.08368 kj.
Conversion Chart
This chart shows the conversions from calories to kilojoules for values between -24.0 and 26.0. To use it, find your calorie value in the first column, then read the corresponding kilojoule value in the second column. It helps quickly estimate energy conversions without calculations.
| Calories | Kilojoules |
|---|---|
| -24.0 | -0.1001 |
| -23.0 | -0.0962 |
| -22.0 | -0.0923 |
| -21.0 | -0.0882 |
| -20.0 | -0.0842 |
| -19.0 | -0.0801 |
| -18.0 | -0.0760 |
| -17.0 | -0.0719 |
| -16.0 | -0.0678 |
| -15.0 | -0.0637 |
| -14.0 | -0.0596 |
| -13.0 | -0.0555 |
| -12.0 | -0.0514 |
| -11.0 | -0.0473 |
| -10.0 | -0.0432 |
| -9.0 | -0.0391 |
| -8.0 | -0.0350 |
| -7.0 | -0.0309 |
| -6.0 | -0.0268 |
| -5.0 | -0.0227 |
| -4.0 | -0.0186 |
| -3.0 | -0.0145 |
| -2.0 | -0.0104 |
| -1.0 | -0.0063 |
| 0.0 | 0.0000 |
| 1.0 | 0.0042 |
| 2.0 | 0.0084 |
| 3.0 | 0.0125 |
| 4.0 | 0.0167 |
| 5.0 | 0.0209 |
| 6.0 | 0.0251 |
| 7.0 | 0.0293 |
| 8.0 | 0.0335 |
| 9.0 | 0.0377 |
| 10.0 | 0.0418 |
| 11.0 | 0.0460 |
| 12.0 | 0.0502 |
| 13.0 | 0.0544 |
| 14.0 | 0.0586 |
| 15.0 | 0.0628 |
| 16.0 | 0.0670 |
| 17.0 | 0.0712 |
| 18.0 | 0.0754 |
| 19.0 | 0.0796 |
| 20.0 | 0.0838 |
| 21.0 | 0.0880 |
| 22.0 | 0.0922 |
| 23.0 | 0.0964 |
| 24.0 | 0.1006 |
| 25.0 | 0.1048 |
| 26.0 | 0.1090 |
Related Conversion Questions
- How many kilojoules are in 1 calorie?
- What is the kj equivalent of 1 calorie?
- How do I convert 1 calorie to kilojoules manually?
- Is 1 calorie equal to 4.2 kj?
- What is the energy in kj for 1 food calorie?
- Can I convert calories to kilojoules in a calculator for 1 calorie?
- What is the formula to change 1 calorie into kj?
Conversion Definitions
A calorie is a unit of energy that measures the amount of heat needed to raise the temperature of one gram of water by one degree Celsius, primarily used in nutrition and food energy. It is equal to approximately 4.184 joules.
Kilojoule (kj) is a metric unit of energy equal to 1000 joules, used in scientific contexts and internationally to quantify energy, work, or heat. It provides a larger scale unit for expressing energy amounts than the calorie.
Conversion FAQs
How accurate is the conversion from calorie to kj?
The conversion from calorie to kj is highly accurate because it relies on the fixed conversion factor 4.184 joules per calorie. Minor variations only occur in different definitions of calorie (small calorie vs. large calorie), but for food, the standard is precise.
Can I use this conversion for other energy units?
This specific conversion applies only to calories and kilojoules. For other units like British thermal units (BTUs) or electronvolts, different formulas and conversion factors are necessary. Always ensure the units are compatible before converting.
Why is the calorie still used in nutrition if the kj is international?
The calorie remains common in nutritional labels due to historical reasons and consumer familiarity. However, many countries adopt kilojoules for clarity and standardization, but both units are often listed together for convenience.
Does converting 1 calorie to kj change based on the calorie type?
Standard food calories (kilocalories) consistently convert to about 4.184 kilojoules. Smaller calories (calories as defined in physics) are the same unit, so the conversion doesn’t change based on calorie type, but context matters for precise scientific calculations.
Last Updated : 13 May, 2025
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Sandeep Bhandari holds a Bachelor of Engineering in Computers from Thapar University (2006). He has 20 years of experience in the technology field. He has a keen interest in various technical fields, including database systems, computer networks, and programming. You can read more about him on his bio page.