1 kcal equals approximately 4.184 kj.
The kilocalorie (kcal) is a unit of energy often used in food energy measurement, while the kilojoule (kj) is the SI unit of energy. Since 1 kcal equals exactly 4184 joules, converting kcal to kj involves multiplying by 4.184.
Conversion Tool
Result in kj:
Conversion Formula
The formula to convert kilocalories (kcal) to kilojoules (kj) is:
kj = kcal × 4.184
This works because 1 kcal equals exactly 4184 joules, and since 1 kj = 1000 joules, 1 kcal = 4.184 kj.
For example, to convert 1 kcal to kj:
- Multiply 1 kcal by 4.184
- 1 × 4.184 = 4.184 kj
Thus, 1 kcal is equal to 4.184 kj.
Conversion Example
- Convert 5 kcal to kj:
- Multiply 5 by 4.184
- 5 × 4.184 = 20.92 kj
- Result: 5 kcal = 20.92 kj
- Convert 10 kcal to kj:
- Multiply 10 by 4.184
- 10 × 4.184 = 41.84 kj
- Result: 10 kcal = 41.84 kj
- Convert 0.5 kcal to kj:
- Multiply 0.5 by 4.184
- 0.5 × 4.184 = 2.092 kj
- Result: 0.5 kcal = 2.092 kj
- Convert 12.7 kcal to kj:
- Multiply 12.7 by 4.184
- 12.7 × 4.184 = 53.177 kj
- Result: 12.7 kcal = 53.177 kj
Conversion Chart
The chart below shows values from -24.0 kcal to 26.0 kcal converted to kilojoules. Use this chart by finding the kcal value in the left column and reading across its equivalent in kj in the right column.
| kcal | kj |
|---|---|
| -24.0 | -100.416 |
| -20.0 | -83.680 |
| -16.0 | -66.944 |
| -12.0 | -50.208 |
| -8.0 | -33.472 |
| -4.0 | -16.736 |
| 0.0 | 0.000 |
| 4.0 | 16.736 |
| 8.0 | 33.472 |
| 12.0 | 50.208 |
| 16.0 | 66.944 |
| 20.0 | 83.680 |
| 24.0 | 100.416 |
| 26.0 | 108.784 |
Related Conversion Questions
- How many kilojoules are in 1 kcal?
- What is the kj equivalent of 1 kcal in energy?
- Can 1 kcal be converted directly to kj?
- How do I change 1 kcal into kj using a formula?
- Is 1 kcal more or less than 4 kj?
- Why is 1 kcal equal to 4.184 kj?
- What does 1 kcal convert to in kilojoules exactly?
Conversion Definitions
kcal: The kilocalorie, often called simply calorie in food contexts, measures energy. It equals 1000 calories, where one calorie is the energy needed to raise 1 gram of water by 1°C. kcal is widely used to quantify food energy content in nutrition labels.
kj: Kilojoule is the standard unit of energy in the International System of Units. One kilojoule equals 1000 joules. It measures energy, work, or heat, used globally in scientific and nutritional contexts as a precise energy unit.
Conversion FAQs
Is the conversion factor between kcal and kj exact or approximate?
The conversion factor 4.184 kj per 1 kcal is exact by definition. It comes from the precise energy needed to raise water temperature and the joule’s definition. However, rounded values like 4.18 are sometimes used, but 4.184 is the scientifically accepted number.
Why is kcal used more in some countries while kj in others?
Many countries like the US and UK use kcal on nutrition labels because of tradition and familiarity. Other countries, mainly those using SI units, prefer kj as it’s consistent with the metric system. Both measure energy, but kj aligns better with scientific standards.
Can negative kcal values be converted to kj?
Yes, negative kcal values convert to negative kj values using the same multiplication. Negative energy values may represent energy loss or consumption in some contexts, so the conversion remains valid mathematically.
Does the conversion change with temperature or pressure?
No, the conversion constant between kcal and kj is fixed and does not depend on temperature or pressure. It’s based on defined units of energy, independent of environmental conditions.
Are there any other units related to kcal and kj for energy?
Other energy units include the calorie (cal), joule (J), British Thermal Unit (BTU), and electronvolt (eV). kcal and kj are larger scale units suitable for food energy, while joules are the SI base unit.