How do you convert kilocalories to kilojoules?

To convert kilocalories (kcal) to kilojoules (kJ), multiply the energy in kilocalories by 4.184 (kilojoules = kilocalories × 4.184).

What is 500 kilocalories in kilojoules?

500 kilocalories (500 kcal) is equal to 2,092 kilojoules (2,092 kJ).

Which is larger, 1 kilocalorie (food calorie) (kcal) or 1 kilojoule (kJ)?

One kilocalorie (food calorie) (kcal) is larger than one kilojoule (kJ). Specifically, 1 kcal contains 4.184 kJ, whereas 1 kJ is 0.23901 kcal.

How do I convert back from kilojoules (kJ) to kilocalories (kcal)?

To reverse the calculation from kJ to kcal, multiply your kilojoule value by the inverse factor 0.23901 (or divide by 4.184). You can also click the Swap button in the tool above to flip directions in one click.

How many decimal places should I round kcal to kJ results to?

For everyday comparisons and quick estimates, rounding to 2 decimal places is usually sufficient (for example, 500 kcal ≈ 2,092.00 kJ). For engineering, laboratory, or machining specifications, select 4 or 6 decimals—or Scientific (10ⁿ) mode—in the calculator toolbar above.

Kilocalories to Kilojoules Converter

Enter the energy in kilocalories below to convert it to kilojoules.

Kilojoules to Kilocalories (kJ → kcal)

Convert Kilocalories to Kilojoules

Enter a value in kilocalories (kcal) to convert to kilojoules (kJ).

Value (kcal)

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2,092kilojoules

500 kcal = 2,092 kJ

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Reference:NIST CODATA (CODATA Energy & Thermodynamic Constants)

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Kilocalorie to Kilojoule Conversion Table

Table showing various kilocalorie measurements converted to kilojoules. Click any preset value or arrow to load it into the converter.

Kilocalories (kcal)	Kilojoules (kJ)
1 kcal	4.184 kJ
2 kcal	8.368 kJ
5 kcal	20.92 kJ
10 kcal	41.84 kJ
15 kcal	62.76 kJ
20 kcal	83.68 kJ
25 kcal	104.6 kJ
30 kcal	125.52 kJ
50 kcal	209.2 kJ
75 kcal	313.8 kJ

How to Convert Kilocalories to Kilojoules

To convert kilocalories to kilojoules, multiply the energy by the following conversion ratio: 4.184 kilojoules/kilocalorie.

Since one kilocalorie is equal to 4.184 kilojoules, you can use this simple formula to convert:

kilojoules = kilocalories × 4.184

The energy in kilojoules is equal to the energy in kilocalories multiplied by 4.184.

For example, here's how to convert 500 kilocalories to kilojoules using the formula above.

kilojoules = (500 kcal × 4.184) = 2,092 kJ

How Many Kilojoules Are in a Kilocalorie?

There are 4.184 kilojoules in a kilocalorie, which is why we use this value in the formula above.

1 kcal = 4.184 kJ|1 kJ = 0.2390057 kcal

Our kilocalorie to kilojoule calculator automatically converts your energy measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.

Kilocalories and kilojoules are both units used to measure energy. Keep reading to learn more about each unit.

What Is a Kilocalorie?

A kilocalorie is a unit of energy equal to 4,184 joules (J), the base unit for energy. Dietary Calorie equal to 1,000 small calories (4,184 Joules). [1]

The kilocalorie is classified as a standard unit of energy. Kilocalories can be abbreviated as kcal; for example, 1 kilocalorie can be written as 1 kcal.

In the metric system, "kilo" is the standard SI prefix for thousands, or 10³. This makes the kilocalorie (kcal) a convenient decimal multiple of the calorie (cal).

In practice, kilocalories (kcal) are widely used across large-scale industrial, bulk, and macro-level energy specifications within international standard workflows, engineering documentation, and technical data sheets.

Learn more about kilocalories in our Energy Converter.

What Is a Kilojoule?

A kilojoule is a unit of energy equal to 1,000 joules (J), the base unit for energy. Equal to 1,000 Joules. [2]

The kilojoule is classified as a metric and SI-compatible unit of energy. Kilojoules can be abbreviated as kJ; for example, 1 kilojoule can be written as 1 kJ.

In the metric system, "kilo" is the standard SI prefix for thousands, or 10³. This makes the kilojoule (kJ) a convenient decimal multiple of the joule (J).

In practice, kilojoules (kJ) are widely used across large-scale industrial, bulk, and macro-level energy specifications within SI metric workflows, engineering documentation, and technical data sheets.

Learn more about kilojoules in our Energy Converter.

When converting energy between kilocalories (kcal) and kilojoules (kJ), keep full floating-point precision (1 kcal = 4.184 kJ; 1 kJ = 0.2390057 kcal) during intermediate calculations and round only the final kilojoule figure to match your instrument tolerance.

More Kilocalorie & Kilojoule Conversions

Need to calculate in the opposite direction? Use our kilojoules to kilocalories converter (kJ to kcal) to switch your starting unit immediately. You can also explore related tools such as converting joules to kilojoules, converting joules to calories, or converting calories to joules.

Convert from Kilocalories

Convert to Kilojoules

Frequently Asked Questions

There are 4.184 kilojoules (kJ) in 1 kilocalorie (kcal). Conversely, 1 kilojoule (kJ) is equal to 0.23901 kilocalories (kcal).

Energy Converter

Quick Info

Direct Factor: 1 kilocalorie (food calorie) (kcal) equals 4.184 kilojoules (kJ).
Inverse Factor: 1 kilojoule (kJ) equals 0.23901 kilocalories (kcal).
Formula: kilojoules = kilocalories × 4.184.
Verified Precision: Anchored to official NIST SP 811 and ISO/IEC 80000 standards.

Units Comparison

Kilocalorie (Food Calorie) (kcal)

Dietary Calorie equal to 1,000 small calories (4,184 Joules).

Kilojoule (kJ)

Equal to 1,000 Joules.

Joule (J)

Coherent SI unit of energy and work (1 W·s = 1 N·m).

References

[1]NIST CODATA · CODATA Energy & Thermodynamic Constants
Source
[2]NIST SP 811 · NIST SP 811 App. B.9 (Energy, Work & Heat)
Source
[3]BIPM · Derived SI Unit: Joule (J)
Source

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References

NIST · BIPM · ISO

[1]
NIST CODATA (CODATA Energy & Thermodynamic Constants)·Energy Metrology Standard — Kilocalories (kcal) to Kilojoules (kJ)
NIST CODATA Standard
[2]
NIST SP 811 (NIST SP 811 App. B.9 (Energy, Work & Heat))·Unit Specifications: Kilocalorie (Food Calorie) (kcal) & Kilojoule (kJ)
NIST SP 811 Specification
[3]
BIPM (Derived SI Unit: Joule (J))·Conversion Factors & Mathematical Basis (kcal to kJ)
BIPM Reference

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