A zeptojoule (zJ) is a metric-prefixed unit of energy equal to 10-21 joules, a fraction of a single joule, using the SI zepto prefix.
Zeptojoules to Calories
Convert Zeptojoule (zJ) to Calorie (cal) instantly with an exact formula, conversion table, and FAQ.
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Convert zeptojoules (zJ) to calories (cal) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
A (small) calorie is a thermochemical unit of heat energy equal to 4.184 joules, historically the energy needed to raise 1 gram of water by 1°C.
cal = zJ × 2.390057361e-22
Results update instantly for Zeptojoules to Calories conversions.
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Formula
cal = zJ × 2.390057361e-22
zJ = cal × 4.184000000e+21
Conversion table
| 1 zJ | 2.390057e-22 cal |
| 5 zJ | 1.195029e-21 cal |
| 10 zJ | 2.390057e-21 cal |
| 20 zJ | 4.780115e-21 cal |
| 50 zJ | 1.195029e-20 cal |
| 100 zJ | 2.390057e-20 cal |
| 500 zJ | 1.195029e-19 cal |
| 1000 zJ | 2.390057e-19 cal |
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How the formula works
Both zeptojoule and calorie measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in zeptojoules by 2.390057361e-22 to get calories. To reverse the conversion, multiply a calorie value by 4.184000000e+21 to get back to zeptojoules.
Frequently asked questions
What is Zeptojoule (zJ)?
A zeptojoule (zJ) is a metric-prefixed unit of energy equal to 10-21 joules, a fraction of a single joule, using the SI zepto prefix.
What is Calorie (cal)?
A (small) calorie is a thermochemical unit of heat energy equal to 4.184 joules, historically the energy needed to raise 1 gram of water by 1°C.
How do I convert zeptojoules to calories?
Multiply the zeptojoule value by 2.390057361e-22 to get the equivalent in calories. For example, 5 zJ × 2.390057361e-22 = 1.195029e-21 cal.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 2.390057361e-22 is an exact, non-rounded value.
Can I convert calories back to zeptojoules?
Yes. Divide the calorie value by 2.390057361e-22, or multiply it by 4.184000000e+21, to get zeptojoules.
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About converting zeptojoules to calories
A zeptojoule (zJ) is a metric-prefixed unit of energy equal to 10-21 joules, a fraction of a single joule, using the SI zepto prefix. A (small) calorie is a thermochemical unit of heat energy equal to 4.184 joules, historically the energy needed to raise 1 gram of water by 1°C.
Use this calculator to move between zeptojoules and calories accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.