A kilocalorie (kcal) equals 1,000 small calories and is the unit behind the food "Calorie" shown on nutrition labels.
Kilocalories to Ronnajoules
Convert Kilocalorie (kcal) to Ronnajoule (RJ) instantly with an exact formula, conversion table, and FAQ.
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Convert kilocalories (kcal) to ronnajoules (RJ) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
A ronnajoule (RJ) is a metric-prefixed unit of energy equal to 1027 joules, using the SI ronna prefix.
RJ = kcal × 4.184000000e-24
Results update instantly for Kilocalories to Ronnajoules conversions.
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Formula
RJ = kcal × 4.184000000e-24
kcal = RJ × 2.390057361e+23
Conversion table
| 1 kcal | 4.184000e-24 RJ |
| 5 kcal | 2.092000e-23 RJ |
| 10 kcal | 4.184000e-23 RJ |
| 20 kcal | 8.368000e-23 RJ |
| 50 kcal | 2.092000e-22 RJ |
| 100 kcal | 4.184000e-22 RJ |
| 500 kcal | 2.092000e-21 RJ |
| 1000 kcal | 4.184000e-21 RJ |
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How the formula works
Both kilocalorie and ronnajoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in kilocalories by 4.184000000e-24 to get ronnajoules. To reverse the conversion, multiply a ronnajoule value by 2.390057361e+23 to get back to kilocalories.
Frequently asked questions
What is Kilocalorie (kcal)?
A kilocalorie (kcal) equals 1,000 small calories and is the unit behind the food "Calorie" shown on nutrition labels.
What is Ronnajoule (RJ)?
A ronnajoule (RJ) is a metric-prefixed unit of energy equal to 1027 joules, using the SI ronna prefix.
How do I convert kilocalories to ronnajoules?
Multiply the kilocalorie value by 4.184000000e-24 to get the equivalent in ronnajoules. For example, 5 kcal × 4.184000000e-24 = 2.092000e-23 RJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 4.184000000e-24 is an exact, non-rounded value.
Can I convert ronnajoules back to kilocalories?
Yes. Divide the ronnajoule value by 4.184000000e-24, or multiply it by 2.390057361e+23, to get kilocalories.
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About converting kilocalories to ronnajoules
A kilocalorie (kcal) equals 1,000 small calories and is the unit behind the food "Calorie" shown on nutrition labels. A ronnajoule (RJ) is a metric-prefixed unit of energy equal to 1027 joules, using the SI ronna prefix.
Use this calculator to move between kilocalories and ronnajoules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.